diff --git a/benches/bench.rs b/benches/bench.rs
index d50cf43..c3799fb 100644
--- a/benches/bench.rs
+++ b/benches/bench.rs
@@ -1,4 +1,4 @@
-use annotate_snippets::{level::Level, AnnotationKind, Group, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
 
 #[divan::bench]
 fn simple() -> String {
@@ -24,7 +24,7 @@ fn simple() -> String {
             _ => continue,
         }
     }"#;
-    let message = Level::ERROR.message("mismatched types").id("E0308").group(
+    let message = Level::ERROR.header("mismatched types").id("E0308").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(51)
@@ -69,7 +69,7 @@ fn fold(bencher: divan::Bencher<'_, '_>, context: usize) {
             (input, span)
         })
         .bench_values(|(input, span)| {
-            let message = Level::ERROR.message("mismatched types").id("E0308").group(
+            let message = Level::ERROR.header("mismatched types").id("E0308").group(
                 Group::new().element(
                     Snippet::source(&input)
                         .fold(true)
diff --git a/examples/custom_error.rs b/examples/custom_error.rs
index 4050d40..b9e27b3 100644
--- a/examples/custom_error.rs
+++ b/examples/custom_error.rs
@@ -1,5 +1,5 @@
 use annotate_snippets::renderer::OutputTheme;
-use annotate_snippets::{level::Level, AnnotationKind, Group, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
 
 fn main() {
     let source = r#"//@ compile-flags: -Ztreat-err-as-bug
@@ -17,7 +17,7 @@ pub static C: u32 = 0 - 1;
 "#;
     let message = Level::ERROR
         .text(Some("error: internal compiler error"))
-        .message("could not evaluate static initializer")
+        .header("could not evaluate static initializer")
         .id("E0080")
         .group(
             Group::new().element(
diff --git a/examples/custom_level.rs b/examples/custom_level.rs
index 804f774..b2af361 100644
--- a/examples/custom_level.rs
+++ b/examples/custom_level.rs
@@ -1,5 +1,5 @@
 use annotate_snippets::renderer::OutputTheme;
-use annotate_snippets::{level::Level, AnnotationKind, Group, Patch, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Patch, Renderer, Snippet};
 
 fn main() {
     let source = r#"// Regression test for issue #114529
@@ -30,7 +30,7 @@ fn main() {
 }
 "#;
     let message = Level::ERROR
-        .message("`break` with value from a `while` loop")
+        .header("`break` with value from a `while` loop")
         .id("E0571")
         .group(
             Group::new().element(
diff --git a/examples/expected_type.rs b/examples/expected_type.rs
index 9a51dce..02abdec 100644
--- a/examples/expected_type.rs
+++ b/examples/expected_type.rs
@@ -1,4 +1,4 @@
-use annotate_snippets::{level::Level, AnnotationKind, Group, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
 
 fn main() {
     let source = r#"                annotations: vec![SourceAnnotation {
@@ -6,7 +6,7 @@ fn main() {
                     ,
                 range: <22, 25>,"#;
     let message =
-        Level::ERROR.message("expected type, found `22`").group(
+        Level::ERROR.header("expected type, found `22`").group(
             Group::new().element(
                 Snippet::source(source)
                     .line_start(26)
diff --git a/examples/footer.rs b/examples/footer.rs
index d61e84b..ca6f1dc 100644
--- a/examples/footer.rs
+++ b/examples/footer.rs
@@ -1,8 +1,8 @@
-use annotate_snippets::{level::Level, AnnotationKind, Group, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
 
 fn main() {
     let message = Level::ERROR
-        .message("mismatched types")
+        .header("mismatched types")
         .id("E0308")
         .group(
             Group::new().element(
diff --git a/examples/format.rs b/examples/format.rs
index 5324413..4b688d4 100644
--- a/examples/format.rs
+++ b/examples/format.rs
@@ -1,4 +1,4 @@
-use annotate_snippets::{level::Level, AnnotationKind, Group, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
 
 fn main() {
     let source = r#") -> Option<String> {
@@ -23,7 +23,7 @@ fn main() {
             _ => continue,
         }
     }"#;
-    let message = Level::ERROR.message("mismatched types").id("E0308").group(
+    let message = Level::ERROR.header("mismatched types").id("E0308").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(51)
diff --git a/examples/highlight_source.rs b/examples/highlight_source.rs
index 9962542..92d8114 100644
--- a/examples/highlight_source.rs
+++ b/examples/highlight_source.rs
@@ -1,4 +1,4 @@
-use annotate_snippets::{level::Level, AnnotationKind, Group, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
 
 fn main() {
     let source = r#"//@ compile-flags: -Z teach
@@ -10,7 +10,7 @@ const CON: Vec<i32> = vec![1, 2, 3]; //~ ERROR E0010
 fn main() {}
 "#;
     let message = Level::ERROR
-        .message("allocations are not allowed in constants")
+        .header("allocations are not allowed in constants")
         .id("E0010")
         .group(
             Group::new()
diff --git a/examples/highlight_title.rs b/examples/highlight_title.rs
index e2da54f..12c106a 100644
--- a/examples/highlight_title.rs
+++ b/examples/highlight_title.rs
@@ -1,4 +1,4 @@
-use annotate_snippets::{level::Level, AnnotationKind, Group, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
 use anstyle::Effects;
 
 fn main() {
@@ -43,7 +43,7 @@ fn main() {
         magenta.render_reset()
     );
 
-    let message = Level::ERROR.message("mismatched types").id("E0308").group(
+    let message = Level::ERROR.header("mismatched types").id("E0308").group(
         Group::new()
             .element(
                 Snippet::source(source)
diff --git a/examples/multislice.rs b/examples/multislice.rs
index ddd938e..a7d340a 100644
--- a/examples/multislice.rs
+++ b/examples/multislice.rs
@@ -1,7 +1,7 @@
-use annotate_snippets::{level::Level, Annotation, Group, Renderer, Snippet};
+use annotate_snippets::{Annotation, Group, Level, Renderer, Snippet};
 
 fn main() {
-    let message = Level::ERROR.message("mismatched types").group(
+    let message = Level::ERROR.header("mismatched types").group(
         Group::new()
             .element(
                 Snippet::<Annotation<'_>>::source("Foo")
diff --git a/src/level.rs b/src/level.rs
index 7f92024..87d1a9f 100644
--- a/src/level.rs
+++ b/src/level.rs
@@ -1,49 +1,47 @@
+//! [`Level`] constants for easy importing
+
 use crate::renderer::stylesheet::Stylesheet;
 use crate::snippet::{ERROR_TXT, HELP_TXT, INFO_TXT, NOTE_TXT, WARNING_TXT};
 use crate::{Element, Group, Message, Title};
 use anstyle::Style;
 
+/// Default `error:` [`Level`]
 pub const ERROR: Level<'_> = Level {
     name: None,
     level: LevelInner::Error,
 };
 
+/// Default `warning:` [`Level`]
 pub const WARNING: Level<'_> = Level {
     name: None,
     level: LevelInner::Warning,
 };
 
+/// Default `info:` [`Level`]
 pub const INFO: Level<'_> = Level {
     name: None,
     level: LevelInner::Info,
 };
 
+/// Default `note:` [`Level`]
 pub const NOTE: Level<'_> = Level {
     name: None,
     level: LevelInner::Note,
 };
 
+/// Default `help:` [`Level`]
 pub const HELP: Level<'_> = Level {
     name: None,
     level: LevelInner::Help,
 };
 
+/// [`Message`] or [`Title`] severity level
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Level<'a> {
     pub(crate) name: Option<Option<&'a str>>,
     pub(crate) level: LevelInner,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
-pub enum Level2<'a> {
-    Builtin(LevelInner),
-    Custom {
-        name: Option<&'a str>,
-        level: LevelInner,
-    },
-    None,
-}
-
 impl<'a> Level<'a> {
     pub const ERROR: Level<'a> = ERROR;
     pub const WARNING: Level<'a> = WARNING;
@@ -51,9 +49,13 @@ impl<'a> Level<'a> {
     pub const NOTE: Level<'a> = NOTE;
     pub const HELP: Level<'a> = HELP;
 
+    /// <div class="warning">
+    ///
     /// Text passed to this function is considered "untrusted input", as such
     /// all text is passed through a normalization function. Pre-styled text is
     /// not allowed to be passed to this function.
+    ///
+    /// </div>
     pub fn text(self, text: Option<&'a str>) -> Level<'a> {
         Level {
             name: Some(text),
@@ -63,24 +65,32 @@ impl<'a> Level<'a> {
 }
 
 impl<'a> Level<'a> {
+    /// <div class="warning">
+    ///
     /// Text passed to this function is considered "untrusted input", as such
     /// all text is passed through a normalization function. Pre-styled text is
     /// not allowed to be passed to this function.
-    pub fn message(self, title: &'a str) -> Message<'a> {
+    ///
+    /// </div>
+    pub fn header(self, header: &'a str) -> Message<'a> {
         Message {
             id: None,
             groups: vec![Group::new().element(Element::Title(Title {
                 level: self,
-                title,
+                title: header,
                 primary: true,
             }))],
         }
     }
 
+    /// <div class="warning">
+    ///
     /// Text passed to this function is allowed to be pre-styled, as such all
     /// text is considered "trusted input" and has no normalizations applied to
     /// it. [`normalize_untrusted_str`](crate::normalize_untrusted_str) can be
     /// used to normalize untrusted text before it is passed to this function.
+    ///
+    /// </div>
     pub fn title(self, title: &'a str) -> Title<'a> {
         Title {
             level: self,
@@ -107,7 +117,7 @@ impl<'a> Level<'a> {
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
-pub enum LevelInner {
+pub(crate) enum LevelInner {
     Error,
     Warning,
     Info,
diff --git a/src/lib.rs b/src/lib.rs
index eee2b6f..76836d0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -53,7 +53,8 @@ pub fn normalize_untrusted_str(s: &str) -> String {
     renderer::normalize_whitespace(s)
 }
 
+#[doc(inline)]
+pub use level::Level;
 #[doc(inline)]
 pub use renderer::Renderer;
-pub use snippet::ColumnSeparator;
 pub use snippet::*;
diff --git a/src/renderer/mod.rs b/src/renderer/mod.rs
index 8efcff8..be2abab 100644
--- a/src/renderer/mod.rs
+++ b/src/renderer/mod.rs
@@ -5,7 +5,7 @@
 //! # Example
 //! ```
 //! use annotate_snippets::*;
-//! use annotate_snippets::level::Level;
+//! use annotate_snippets::Level;
 //!
 //! let source = r#"
 //! use baz::zed::bar;
@@ -19,7 +19,7 @@
 //! }
 //! "#;
 //! Level::ERROR
-//!     .message("unresolved import `baz::zed`")
+//!     .header("unresolved import `baz::zed`")
 //!     .id("E0432")
 //!     .group(
 //!         Group::new().element(
@@ -101,7 +101,7 @@ impl Renderer {
                 info: BRIGHT_BLUE.effects(Effects::BOLD),
                 note: AnsiColor::BrightGreen.on_default().effects(Effects::BOLD),
                 help: AnsiColor::BrightCyan.on_default().effects(Effects::BOLD),
-                line_no: BRIGHT_BLUE.effects(Effects::BOLD),
+                line_num: BRIGHT_BLUE.effects(Effects::BOLD),
                 emphasis: if USE_WINDOWS_COLORS {
                     AnsiColor::BrightWhite.on_default()
                 } else {
@@ -178,8 +178,8 @@ impl Renderer {
     }
 
     /// Set the output style for line numbers
-    pub const fn line_no(mut self, style: Style) -> Self {
-        self.stylesheet.line_no = style;
+    pub const fn line_num(mut self, style: Style) -> Self {
+        self.stylesheet.line_num = style;
         self
     }
 
@@ -383,7 +383,7 @@ impl Renderer {
                         self.render_origin(buffer, max_line_num_len, origin);
                         last_was_suggestion = false;
                     }
-                    Element::ColumnSeparator(_) => {
+                    Element::Padding(_) => {
                         self.draw_col_separator_no_space(
                             buffer,
                             buffer.num_lines(),
@@ -430,7 +430,7 @@ impl Renderer {
 
         let (has_primary_spans, has_span_labels) =
             next_section.map_or((false, false), |s| match s {
-                Element::Title(_) | Element::ColumnSeparator(_) => (false, false),
+                Element::Title(_) | Element::Padding(_) => (false, false),
                 Element::Cause(cause) => (
                     cause.markers.iter().any(|m| m.kind.is_primary()),
                     cause.markers.iter().any(|m| m.label.is_some()),
@@ -1523,7 +1523,7 @@ impl Renderer {
             }
             if suggestion.origin != primary_origin {
                 if let Some(origin) = suggestion.origin {
-                    let (loc, _) = sm.span_to_locations(parts[0].range.clone());
+                    let (loc, _) = sm.span_to_locations(parts[0].span.clone());
                     // --> file.rs:line:col
                     //  |
                     let arrow = self.file_start();
@@ -1563,8 +1563,8 @@ impl Renderer {
                 row_num += 1;
             }
 
-            let file_lines = sm.span_to_lines(parts[0].range.clone());
-            let (line_start, line_end) = sm.span_to_locations(parts[0].range.clone());
+            let file_lines = sm.span_to_lines(parts[0].span.clone());
+            let (line_start, line_end) = sm.span_to_locations(parts[0].span.clone());
             let mut lines = complete.lines();
             if lines.clone().next().is_none() {
                 // Account for a suggestion to completely remove a line(s) with whitespace (#94192).
@@ -1697,8 +1697,8 @@ impl Renderer {
                 // already existing code, despite the colors and UI elements.
                 // We special case `#[derive(_)]\n` and other attribute suggestions, because those
                 // are the ones where context is most useful.
-                let file_lines = sm.span_to_lines(parts[0].range.end..parts[0].range.end);
-                let (lo, _) = sm.span_to_locations(parts[0].range.clone());
+                let file_lines = sm.span_to_lines(parts[0].span.end..parts[0].span.end);
+                let (lo, _) = sm.span_to_locations(parts[0].span.clone());
                 let line_num = lo.line;
                 if let Some(line) = sm.get_line(line_num) {
                     let line = normalize_whitespace(line);
@@ -1724,7 +1724,7 @@ impl Renderer {
                 show_code_change
             {
                 for part in parts {
-                    let (span_start, span_end) = sm.span_to_locations(part.range.clone());
+                    let (span_start, span_end) = sm.span_to_locations(part.span.clone());
                     let span_start_pos = span_start.display;
                     let span_end_pos = span_end.display;
 
@@ -1764,7 +1764,7 @@ impl Renderer {
                     let padding: usize = max_line_num_len + 3;
                     for p in underline_start..underline_end {
                         if matches!(show_code_change, DisplaySuggestion::Underline)
-                            && is_different(sm, part.replacement, part.range.clone())
+                            && is_different(sm, part.replacement, part.span.clone())
                         {
                             // If this is a replacement, underline with `~`, if this is an addition
                             // underline with `+`.
@@ -2665,7 +2665,7 @@ impl ElementStyle {
             ElementStyle::Addition => stylesheet.addition,
             ElementStyle::Removal => stylesheet.removal,
             ElementStyle::LineAndColumn => stylesheet.none,
-            ElementStyle::LineNumber => stylesheet.line_no,
+            ElementStyle::LineNumber => stylesheet.line_num,
             ElementStyle::Quotation => stylesheet.none,
             ElementStyle::MainHeaderMsg => stylesheet.emphasis,
             ElementStyle::UnderlinePrimary | ElementStyle::LabelPrimary => level.style(stylesheet),
diff --git a/src/renderer/source_map.rs b/src/renderer/source_map.rs
index 33fe189..d014bb0 100644
--- a/src/renderer/source_map.rs
+++ b/src/renderer/source_map.rs
@@ -129,8 +129,8 @@ impl<'a> SourceMap<'a> {
         let source_len = self.source.len();
         if let Some(bigger) = annotations.iter().find_map(|x| {
             // Allow highlighting one past the last character in the source.
-            if source_len + 1 < x.range.end {
-                Some(&x.range)
+            if source_len + 1 < x.span.end {
+                Some(&x.span)
             } else {
                 None
             }
@@ -150,13 +150,13 @@ impl<'a> SourceMap<'a> {
         let mut multiline_annotations = vec![];
 
         for Annotation {
-            range,
+            span,
             label,
             kind,
             highlight_source,
         } in annotations
         {
-            let (lo, mut hi) = self.span_to_locations(range.clone());
+            let (lo, mut hi) = self.span_to_locations(span.clone());
 
             // Watch out for "empty spans". If we get a span like 6..6, we
             // want to just display a `^` at 6, so convert that to
@@ -374,13 +374,13 @@ impl<'a> SourceMap<'a> {
         }
         // Assumption: all spans are in the same file, and all spans
         // are disjoint. Sort in ascending order.
-        patches.sort_by_key(|p| p.range.start);
+        patches.sort_by_key(|p| p.span.start);
 
         // Find the bounding span.
-        let Some(lo) = patches.iter().map(|p| p.range.start).min() else {
+        let Some(lo) = patches.iter().map(|p| p.span.start).min() else {
             return Vec::new();
         };
-        let Some(hi) = patches.iter().map(|p| p.range.end).max() else {
+        let Some(hi) = patches.iter().map(|p| p.span.end).max() else {
             return Vec::new();
         };
 
@@ -410,7 +410,7 @@ impl<'a> SourceMap<'a> {
             // suggestion and snippet to look as if we just suggested to add
             // `"b"`, which is typically much easier for the user to understand.
             part.trim_trivial_replacements(self);
-            let (cur_lo, cur_hi) = self.span_to_locations(part.range.clone());
+            let (cur_lo, cur_hi) = self.span_to_locations(part.span.clone());
             if prev_hi.line == cur_lo.line {
                 let mut count = push_trailing(&mut buf, prev_line, &prev_hi, Some(&cur_lo));
                 while count > 0 {
@@ -454,7 +454,7 @@ impl<'a> SourceMap<'a> {
                     _ => 1,
                 })
                 .sum();
-            if !is_different(self, part.replacement, part.range.clone()) {
+            if !is_different(self, part.replacement, part.span.clone()) {
                 // Account for cases where we are suggesting the same code that's already
                 // there. This shouldn't happen often, but in some cases for multipart
                 // suggestions it's much easier to handle it here than in the origin.
diff --git a/src/renderer/styled_buffer.rs b/src/renderer/styled_buffer.rs
index 7114683..c9b805a 100644
--- a/src/renderer/styled_buffer.rs
+++ b/src/renderer/styled_buffer.rs
@@ -2,9 +2,9 @@
 //!
 //! [styled_buffer]: https://github.com/rust-lang/rust/blob/894f7a4ba6554d3797404bbf550d9919df060b97/compiler/rustc_errors/src/styled_buffer.rs
 
-use crate::level::Level;
 use crate::renderer::stylesheet::Stylesheet;
 use crate::renderer::ElementStyle;
+use crate::Level;
 
 use std::fmt;
 use std::fmt::Write;
diff --git a/src/renderer/stylesheet.rs b/src/renderer/stylesheet.rs
index 4aa21a5..075cad4 100644
--- a/src/renderer/stylesheet.rs
+++ b/src/renderer/stylesheet.rs
@@ -7,7 +7,7 @@ pub(crate) struct Stylesheet {
     pub(crate) info: Style,
     pub(crate) note: Style,
     pub(crate) help: Style,
-    pub(crate) line_no: Style,
+    pub(crate) line_num: Style,
     pub(crate) emphasis: Style,
     pub(crate) none: Style,
     pub(crate) context: Style,
@@ -29,7 +29,7 @@ impl Stylesheet {
             info: Style::new(),
             note: Style::new(),
             help: Style::new(),
-            line_no: Style::new(),
+            line_num: Style::new(),
             emphasis: Style::new(),
             none: Style::new(),
             context: Style::new(),
diff --git a/src/snippet.rs b/src/snippet.rs
index fe1239d..03bfe3d 100644
--- a/src/snippet.rs
+++ b/src/snippet.rs
@@ -1,7 +1,7 @@
 //! Structures used as an input for the library.
 
-use crate::level::Level;
 use crate::renderer::source_map::SourceMap;
+use crate::Level;
 use std::ops::Range;
 
 pub(crate) const ERROR_TXT: &str = "error";
@@ -10,6 +10,7 @@ pub(crate) const INFO_TXT: &str = "info";
 pub(crate) const NOTE_TXT: &str = "note";
 pub(crate) const WARNING_TXT: &str = "warning";
 
+/// Top-level user message
 #[derive(Debug)]
 pub struct Message<'a> {
     pub(crate) id: Option<&'a str>, // for "correctness", could be sloppy and be on Title
@@ -17,11 +18,19 @@ pub struct Message<'a> {
 }
 
 impl<'a> Message<'a> {
+    /// <div class="warning">
+    ///
+    /// Text passed to this function is considered "untrusted input", as such
+    /// all text is passed through a normalization function. Pre-styled text is
+    /// not allowed to be passed to this function.
+    ///
+    /// </div>
     pub fn id(mut self, id: &'a str) -> Self {
         self.id = Some(id);
         self
     }
 
+    /// Add an [`Element`] container
     pub fn group(mut self, group: Group<'a>) -> Self {
         self.groups.push(group);
         self
@@ -34,12 +43,12 @@ impl<'a> Message<'a> {
                 v.elements
                     .iter()
                     .map(|s| match s {
-                        Element::Title(_) | Element::Origin(_) | Element::ColumnSeparator(_) => 0,
+                        Element::Title(_) | Element::Origin(_) | Element::Padding(_) => 0,
                         Element::Cause(cause) => {
                             let end = cause
                                 .markers
                                 .iter()
-                                .map(|a| a.range.end)
+                                .map(|a| a.span.end)
                                 .max()
                                 .unwrap_or(cause.source.len())
                                 .min(cause.source.len());
@@ -50,7 +59,7 @@ impl<'a> Message<'a> {
                             let end = suggestion
                                 .markers
                                 .iter()
-                                .map(|a| a.range.end)
+                                .map(|a| a.span.end)
                                 .max()
                                 .unwrap_or(suggestion.source.len())
                                 .min(suggestion.source.len());
@@ -66,6 +75,7 @@ impl<'a> Message<'a> {
     }
 }
 
+/// An [`Element`] container
 #[derive(Debug)]
 pub struct Group<'a> {
     pub(crate) elements: Vec<Element<'a>>,
@@ -97,6 +107,7 @@ impl<'a> Group<'a> {
     }
 }
 
+/// A section of content within a [`Group`]
 #[derive(Debug)]
 #[non_exhaustive]
 pub enum Element<'a> {
@@ -104,7 +115,7 @@ pub enum Element<'a> {
     Cause(Snippet<'a, Annotation<'a>>),
     Suggestion(Snippet<'a, Patch<'a>>),
     Origin(Origin<'a>),
-    ColumnSeparator(ColumnSeparator),
+    Padding(Padding),
 }
 
 impl<'a> From<Title<'a>> for Element<'a> {
@@ -131,15 +142,19 @@ impl<'a> From<Origin<'a>> for Element<'a> {
     }
 }
 
-impl From<ColumnSeparator> for Element<'_> {
-    fn from(value: ColumnSeparator) -> Self {
-        Self::ColumnSeparator(value)
+impl From<Padding> for Element<'_> {
+    fn from(value: Padding) -> Self {
+        Self::Padding(value)
     }
 }
 
+/// A whitespace [`Element`] in a [`Group`]
 #[derive(Debug)]
-pub struct ColumnSeparator;
+pub struct Padding;
 
+/// A text [`Element`] in a [`Group`]
+///
+/// See [`Level::title`] to create this.
 #[derive(Debug)]
 pub struct Title<'a> {
     pub(crate) level: Level<'a>,
@@ -154,6 +169,7 @@ impl Title<'_> {
     }
 }
 
+/// A source view [`Element`] in a [`Group`]
 #[derive(Debug)]
 pub struct Snippet<'a, T> {
     pub(crate) origin: Option<&'a str>,
@@ -164,9 +180,15 @@ pub struct Snippet<'a, T> {
 }
 
 impl<'a, T: Clone> Snippet<'a, T> {
+    /// The source code to be rendered
+    ///
+    /// <div class="warning">
+    ///
     /// Text passed to this function is considered "untrusted input", as such
     /// all text is passed through a normalization function. Pre-styled text is
     /// not allowed to be passed to this function.
+    ///
+    /// </div>
     pub fn source(source: &'a str) -> Self {
         Self {
             origin: None,
@@ -177,19 +199,28 @@ impl<'a, T: Clone> Snippet<'a, T> {
         }
     }
 
+    /// When manually [`fold`][Self::fold]ing,
+    /// the [`source`][Self::source]s line offset from the original start
     pub fn line_start(mut self, line_start: usize) -> Self {
         self.line_start = line_start;
         self
     }
 
+    /// The location of the [`source`][Self::source] (e.g. a path)
+    ///
+    /// <div class="warning">
+    ///
     /// Text passed to this function is considered "untrusted input", as such
     /// all text is passed through a normalization function. Pre-styled text is
     /// not allowed to be passed to this function.
+    ///
+    /// </div>
     pub fn origin(mut self, origin: &'a str) -> Self {
         self.origin = Some(origin);
         self
     }
 
+    /// Hide lines without [`Annotation`]s
     pub fn fold(mut self, fold: bool) -> Self {
         self.fold = fold;
         self
@@ -197,11 +228,13 @@ impl<'a, T: Clone> Snippet<'a, T> {
 }
 
 impl<'a> Snippet<'a, Annotation<'a>> {
+    /// Highlight and describe a span of text within the [`source`][Self::source]
     pub fn annotation(mut self, annotation: Annotation<'a>) -> Snippet<'a, Annotation<'a>> {
         self.markers.push(annotation);
         self
     }
 
+    /// Highlight and describe spans of text within the [`source`][Self::source]
     pub fn annotations(mut self, annotation: impl IntoIterator<Item = Annotation<'a>>) -> Self {
         self.markers.extend(annotation);
         self
@@ -209,40 +242,55 @@ impl<'a> Snippet<'a, Annotation<'a>> {
 }
 
 impl<'a> Snippet<'a, Patch<'a>> {
+    /// Suggest to the user an edit to the [`source`][Self::source]
     pub fn patch(mut self, patch: Patch<'a>) -> Snippet<'a, Patch<'a>> {
         self.markers.push(patch);
         self
     }
 
+    /// Suggest to the user edits to the [`source`][Self::source]
     pub fn patches(mut self, patches: impl IntoIterator<Item = Patch<'a>>) -> Self {
         self.markers.extend(patches);
         self
     }
 }
 
+/// Highlighted and describe a span of text within a [`Snippet`]
+///
+/// See [`AnnotationKind`] to create an annotation.
 #[derive(Clone, Debug)]
 pub struct Annotation<'a> {
-    pub(crate) range: Range<usize>,
+    pub(crate) span: Range<usize>,
     pub(crate) label: Option<&'a str>,
     pub(crate) kind: AnnotationKind,
     pub(crate) highlight_source: bool,
 }
 
 impl<'a> Annotation<'a> {
+    /// Describe the reason the span is highlighted
+    ///
+    /// This will be styled according to the [`AnnotationKind`]
+    ///
+    /// <div class="warning">
+    ///
     /// Text passed to this function is considered "untrusted input", as such
     /// all text is passed through a normalization function. Pre-styled text is
     /// not allowed to be passed to this function.
+    ///
+    /// </div>
     pub fn label(mut self, label: &'a str) -> Self {
         self.label = Some(label);
         self
     }
 
+    /// Style the source according to the [`AnnotationKind`]
     pub fn highlight_source(mut self, highlight_source: bool) -> Self {
         self.highlight_source = highlight_source;
         self
     }
 }
 
+/// The category of the [`Annotation`]
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub enum AnnotationKind {
     /// Color to [`Message`]'s [`Level`]
@@ -254,7 +302,7 @@ pub enum AnnotationKind {
 impl AnnotationKind {
     pub fn span<'a>(self, span: Range<usize>) -> Annotation<'a> {
         Annotation {
-            range: span,
+            span,
             label: None,
             kind: self,
             highlight_source: false,
@@ -266,18 +314,25 @@ impl AnnotationKind {
     }
 }
 
+/// Suggested edit to the [`Snippet`]
 #[derive(Clone, Debug)]
 pub struct Patch<'a> {
-    pub(crate) range: Range<usize>,
+    pub(crate) span: Range<usize>,
     pub(crate) replacement: &'a str,
 }
 
 impl<'a> Patch<'a> {
+    /// Splice `replacement` into the [`Snippet`] at the `span`
+    ///
+    /// <div class="warning">
+    ///
     /// Text passed to this function is considered "untrusted input", as such
     /// all text is passed through a normalization function. Pre-styled text is
     /// not allowed to be passed to this function.
-    pub fn new(range: Range<usize>, replacement: &'a str) -> Self {
-        Self { range, replacement }
+    ///
+    /// </div>
+    pub fn new(span: Range<usize>, replacement: &'a str) -> Self {
+        Self { span, replacement }
     }
 
     pub(crate) fn is_addition(&self, sm: &SourceMap<'_>) -> bool {
@@ -299,7 +354,7 @@ impl<'a> Patch<'a> {
     pub(crate) fn is_destructive_replacement(&self, sm: &SourceMap<'_>) -> bool {
         self.is_replacement(sm)
             && !sm
-                .span_to_snippet(self.range.clone())
+                .span_to_snippet(self.span.clone())
                 // This should use `is_some_and` when our MSRV is >= 1.70
                 .map_or(false, |s| {
                     as_substr(s.trim(), self.replacement.trim()).is_some()
@@ -307,8 +362,8 @@ impl<'a> Patch<'a> {
     }
 
     fn replaces_meaningful_content(&self, sm: &SourceMap<'_>) -> bool {
-        sm.span_to_snippet(self.range.clone())
-            .map_or(!self.range.is_empty(), |snippet| !snippet.trim().is_empty())
+        sm.span_to_snippet(self.span.clone())
+            .map_or(!self.span.is_empty(), |snippet| !snippet.trim().is_empty())
     }
 
     /// Try to turn a replacement into an addition when the span that is being
@@ -317,17 +372,18 @@ impl<'a> Patch<'a> {
         if self.replacement.is_empty() {
             return;
         }
-        let Some(snippet) = sm.span_to_snippet(self.range.clone()) else {
+        let Some(snippet) = sm.span_to_snippet(self.span.clone()) else {
             return;
         };
 
         if let Some((prefix, substr, suffix)) = as_substr(snippet, self.replacement) {
-            self.range = self.range.start + prefix..self.range.end.saturating_sub(suffix);
+            self.span = self.span.start + prefix..self.span.end.saturating_sub(suffix);
             self.replacement = substr;
         }
     }
 }
 
+/// The location of the [`Snippet`] (e.g. a path)
 #[derive(Clone, Debug)]
 pub struct Origin<'a> {
     pub(crate) origin: &'a str,
@@ -338,9 +394,13 @@ pub struct Origin<'a> {
 }
 
 impl<'a> Origin<'a> {
+    /// <div class="warning">
+    ///
     /// Text passed to this function is considered "untrusted input", as such
     /// all text is passed through a normalization function. Pre-styled text is
     /// not allowed to be passed to this function.
+    ///
+    /// </div>
     pub fn new(origin: &'a str) -> Self {
         Self {
             origin,
@@ -351,11 +411,17 @@ impl<'a> Origin<'a> {
         }
     }
 
+    /// Set the default line number to display
+    ///
+    /// Otherwise this will be inferred from the primary [`Annotation`]
     pub fn line(mut self, line: usize) -> Self {
         self.line = Some(line);
         self
     }
 
+    /// Set the default column to display
+    ///
+    /// Otherwise this will be inferred from the primary [`Annotation`]
     pub fn char_column(mut self, char_column: usize) -> Self {
         self.char_column = Some(char_column);
         self
@@ -366,9 +432,15 @@ impl<'a> Origin<'a> {
         self
     }
 
+    /// Like [`Annotation::label`], but when there is no source
+    ///
+    /// <div class="warning">
+    ///
     /// Text passed to this function is considered "untrusted input", as such
     /// all text is passed through a normalization function. Pre-styled text is
     /// not allowed to be passed to this function.
+    ///
+    /// </div>
     pub fn label(mut self, label: &'a str) -> Self {
         self.label = Some(label);
         self
diff --git a/tests/fixtures/color/ann_eof.toml b/tests/fixtures/color/ann_eof.toml
index ac129f3..ef711de 100644
--- a/tests/fixtures/color/ann_eof.toml
+++ b/tests/fixtures/color/ann_eof.toml
@@ -1,6 +1,6 @@
 [message]
 level = "Error"
-title = "expected `.`, `=`"
+header = "expected `.`, `=`"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/ann_insertion.toml b/tests/fixtures/color/ann_insertion.toml
index 13bc13c..30af1bf 100644
--- a/tests/fixtures/color/ann_insertion.toml
+++ b/tests/fixtures/color/ann_insertion.toml
@@ -1,6 +1,6 @@
 [message]
 level = "Error"
-title = "expected `.`, `=`"
+header = "expected `.`, `=`"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/ann_multiline.toml b/tests/fixtures/color/ann_multiline.toml
index 722c3e1..2a5f206 100644
--- a/tests/fixtures/color/ann_multiline.toml
+++ b/tests/fixtures/color/ann_multiline.toml
@@ -1,7 +1,7 @@
 [message]
 level = "Error"
 id = "E0027"
-title = "pattern does not mention fields `lineno`, `content`"
+header = "pattern does not mention fields `lineno`, `content`"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/ann_multiline2.toml b/tests/fixtures/color/ann_multiline2.toml
index 329beb4..854b38a 100644
--- a/tests/fixtures/color/ann_multiline2.toml
+++ b/tests/fixtures/color/ann_multiline2.toml
@@ -1,7 +1,7 @@
 [message]
 level = "Error"
 id = "E####"
-title = "spacing error found"
+header = "spacing error found"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/ann_removed_nl.toml b/tests/fixtures/color/ann_removed_nl.toml
index 8ed96bc..6ffeb7a 100644
--- a/tests/fixtures/color/ann_removed_nl.toml
+++ b/tests/fixtures/color/ann_removed_nl.toml
@@ -1,6 +1,6 @@
 [message]
 level = "Error"
-title = "expected `.`, `=`"
+header = "expected `.`, `=`"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/ensure-emoji-highlight-width.toml b/tests/fixtures/color/ensure-emoji-highlight-width.toml
index 8d7a14a..669959f 100644
--- a/tests/fixtures/color/ensure-emoji-highlight-width.toml
+++ b/tests/fixtures/color/ensure-emoji-highlight-width.toml
@@ -1,5 +1,5 @@
 [message]
-title = "invalid character ` ` in package name: `haha this isn't a valid name 🐛`, characters must be Unicode XID characters (numbers, `-`, `_`, or most letters)"
+header = "invalid character ` ` in package name: `haha this isn't a valid name 🐛`, characters must be Unicode XID characters (numbers, `-`, `_`, or most letters)"
 level = "Error"
 
 
diff --git a/tests/fixtures/color/fold_ann_multiline.toml b/tests/fixtures/color/fold_ann_multiline.toml
index 745ef42..2cee27d 100644
--- a/tests/fixtures/color/fold_ann_multiline.toml
+++ b/tests/fixtures/color/fold_ann_multiline.toml
@@ -1,7 +1,7 @@
 [message]
 level = "Error"
 id = "E0308"
-title = "mismatched types"
+header = "mismatched types"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/fold_bad_origin_line.toml b/tests/fixtures/color/fold_bad_origin_line.toml
index 3b0d827..2fab2d6 100644
--- a/tests/fixtures/color/fold_bad_origin_line.toml
+++ b/tests/fixtures/color/fold_bad_origin_line.toml
@@ -1,6 +1,6 @@
 [message]
 level = "Error"
-title = ""
+header = ""
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/fold_leading.toml b/tests/fixtures/color/fold_leading.toml
index 564187b..0ef043c 100644
--- a/tests/fixtures/color/fold_leading.toml
+++ b/tests/fixtures/color/fold_leading.toml
@@ -1,7 +1,7 @@
 [message]
 level = "Error"
 id = "E0308"
-title = "invalid type: integer `20`, expected a bool"
+header = "invalid type: integer `20`, expected a bool"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/fold_trailing.toml b/tests/fixtures/color/fold_trailing.toml
index eea6365..91e4ab4 100644
--- a/tests/fixtures/color/fold_trailing.toml
+++ b/tests/fixtures/color/fold_trailing.toml
@@ -1,7 +1,7 @@
 [message]
 level = "Error"
 id = "E0308"
-title = "invalid type: integer `20`, expected a lints table"
+header = "invalid type: integer `20`, expected a lints table"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/issue_9.toml b/tests/fixtures/color/issue_9.toml
index 96ad2c0..f423915 100644
--- a/tests/fixtures/color/issue_9.toml
+++ b/tests/fixtures/color/issue_9.toml
@@ -1,6 +1,6 @@
 [message]
 level = "Error"
-title = "expected one of `.`, `;`, `?`, or an operator, found `for`"
+header = "expected one of `.`, `;`, `?`, or an operator, found `for`"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/multiple_annotations.toml b/tests/fixtures/color/multiple_annotations.toml
index f4c90a4..367c53e 100644
--- a/tests/fixtures/color/multiple_annotations.toml
+++ b/tests/fixtures/color/multiple_annotations.toml
@@ -1,6 +1,6 @@
 [message]
 level = "Error"
-title = ""
+header = ""
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/simple.toml b/tests/fixtures/color/simple.toml
index b70f11c..d5a3647 100644
--- a/tests/fixtures/color/simple.toml
+++ b/tests/fixtures/color/simple.toml
@@ -1,6 +1,6 @@
 [message]
 level = "Error"
-title = "expected one of `.`, `;`, `?`, or an operator, found `for`"
+header = "expected one of `.`, `;`, `?`, or an operator, found `for`"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/strip_line.toml b/tests/fixtures/color/strip_line.toml
index d7af686..18a7805 100644
--- a/tests/fixtures/color/strip_line.toml
+++ b/tests/fixtures/color/strip_line.toml
@@ -1,7 +1,7 @@
 [message]
 level = "Error"
 id = "E0308"
-title = "mismatched types"
+header = "mismatched types"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/strip_line_char.toml b/tests/fixtures/color/strip_line_char.toml
index 6585005..3174ced 100644
--- a/tests/fixtures/color/strip_line_char.toml
+++ b/tests/fixtures/color/strip_line_char.toml
@@ -1,7 +1,7 @@
 [message]
 level = "Error"
 id = "E0308"
-title = "mismatched types"
+header = "mismatched types"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/color/strip_line_non_ws.toml b/tests/fixtures/color/strip_line_non_ws.toml
index 1f085b5..b7844ec 100644
--- a/tests/fixtures/color/strip_line_non_ws.toml
+++ b/tests/fixtures/color/strip_line_non_ws.toml
@@ -1,7 +1,7 @@
 [message]
 level = "Error"
 id = "E0308"
-title = "mismatched types"
+header = "mismatched types"
 
 [[message.sections]]
 type = "Cause"
diff --git a/tests/fixtures/deserialize.rs b/tests/fixtures/deserialize.rs
index 8f45b36..2042966 100644
--- a/tests/fixtures/deserialize.rs
+++ b/tests/fixtures/deserialize.rs
@@ -3,7 +3,7 @@ use std::ops::Range;
 
 use annotate_snippets::renderer::DEFAULT_TERM_WIDTH;
 use annotate_snippets::{
-    level::Level, Annotation, AnnotationKind, Element, Group, Message, Patch, Renderer, Snippet,
+    Annotation, AnnotationKind, Element, Group, Level, Message, Patch, Renderer, Snippet,
 };
 
 #[derive(Deserialize)]
@@ -16,7 +16,7 @@ pub(crate) struct Fixture {
 #[derive(Deserialize)]
 pub struct MessageDef {
     pub level: LevelDef,
-    pub title: String,
+    pub header: String,
     #[serde(default)]
     pub id: Option<String>,
     #[serde(default)]
@@ -27,11 +27,11 @@ impl<'a> From<&'a MessageDef> for Message<'a> {
     fn from(val: &'a MessageDef) -> Self {
         let MessageDef {
             level,
-            title,
+            header,
             id,
             sections,
         } = val;
-        let mut message = Level::from(level).message(title);
+        let mut message = Level::from(level).header(header);
         if let Some(id) = id {
             message = message.id(id);
         }
diff --git a/tests/formatter.rs b/tests/formatter.rs
index 3f0e7cd..75cf853 100644
--- a/tests/formatter.rs
+++ b/tests/formatter.rs
@@ -1,13 +1,11 @@
-use annotate_snippets::{
-    level::Level, Annotation, AnnotationKind, Group, Patch, Renderer, Snippet,
-};
+use annotate_snippets::{Annotation, AnnotationKind, Group, Level, Patch, Renderer, Snippet};
 
 use annotate_snippets::renderer::OutputTheme;
 use snapbox::{assert_data_eq, str};
 
 #[test]
 fn test_i_29() {
-    let snippets = Level::ERROR.message("oops").group(
+    let snippets = Level::ERROR.header("oops").group(
         Group::new().element(
             Snippet::source("First line\r\nSecond oops line")
                 .origin("<current file>")
@@ -29,7 +27,7 @@ error: oops
 
 #[test]
 fn test_point_to_double_width_characters() {
-    let snippets = Level::ERROR.message("").group(
+    let snippets = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source("こんにちは、世界")
                 .origin("<current file>")
@@ -51,7 +49,7 @@ error:
 
 #[test]
 fn test_point_to_double_width_characters_across_lines() {
-    let snippets = Level::ERROR.message("").group(
+    let snippets = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source("おはよう\nございます")
                 .origin("<current file>")
@@ -75,7 +73,7 @@ error:
 
 #[test]
 fn test_point_to_double_width_characters_multiple() {
-    let snippets = Level::ERROR.message("").group(
+    let snippets = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source("お寿司\n食べたい🍣")
                 .origin("<current file>")
@@ -100,7 +98,7 @@ error:
 
 #[test]
 fn test_point_to_double_width_characters_mixed() {
-    let snippets = Level::ERROR.message("").group(
+    let snippets = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source("こんにちは、新しいWorld！")
                 .origin("<current file>")
@@ -122,7 +120,7 @@ error:
 
 #[test]
 fn test_format_title() {
-    let input = Level::ERROR.message("This is a title").id("E0001");
+    let input = Level::ERROR.header("This is a title").id("E0001");
 
     let expected = str![r#"error[E0001]: This is a title"#];
     let renderer = Renderer::plain();
@@ -133,7 +131,7 @@ fn test_format_title() {
 fn test_format_snippet_only() {
     let source = "This is line 1\nThis is line 2";
     let input = Level::ERROR
-        .message("")
+        .header("")
         .group(Group::new().element(Snippet::<Annotation<'_>>::source(source).line_start(5402)));
 
     let expected = str![[r#"
@@ -150,7 +148,7 @@ error:
 fn test_format_snippets_continuation() {
     let src_0 = "This is slice 1";
     let src_1 = "This is slice 2";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new()
             .element(
                 Snippet::<Annotation<'_>>::source(src_0)
@@ -184,7 +182,7 @@ fn test_format_snippet_annotation_standalone() {
     let source = [line_1, line_2].join("\n");
     // In line 2
     let range = 22..24;
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(&source).line_start(5402).annotation(
                 AnnotationKind::Context
@@ -207,7 +205,7 @@ error:
 #[test]
 fn test_format_footer_title() {
     let input = Level::ERROR
-        .message("")
+        .header("")
         .group(Group::new().element(Level::ERROR.title("This __is__ a title")));
     let expected = str![[r#"
 error: 
@@ -223,7 +221,7 @@ error:
 fn test_i26() {
     let source = "short";
     let label = "label";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source).line_start(0).annotation(
                 AnnotationKind::Primary
@@ -240,7 +238,7 @@ fn test_i26() {
 fn test_source_content() {
     let source = "This is an example\nof content lines";
     let input = Level::ERROR
-        .message("")
+        .header("")
         .group(Group::new().element(Snippet::<Annotation<'_>>::source(source).line_start(56)));
     let expected = str![[r#"
 error: 
@@ -255,7 +253,7 @@ error:
 #[test]
 fn test_source_annotation_standalone_singleline() {
     let source = "tests";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -275,7 +273,7 @@ error:
 #[test]
 fn test_source_annotation_standalone_multiline() {
     let source = "tests";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -299,7 +297,7 @@ error:
 #[test]
 fn test_only_source() {
     let input = Level::ERROR
-        .message("")
+        .header("")
         .group(Group::new().element(Snippet::<Annotation<'_>>::source("").origin("file.rs")));
     let expected = str![[r#"
 error: 
@@ -314,7 +312,7 @@ error:
 fn test_anon_lines() {
     let source = "This is an example\nof content lines\n\nabc";
     let input = Level::ERROR
-        .message("")
+        .header("")
         .group(Group::new().element(Snippet::<Annotation<'_>>::source(source).line_start(56)));
     let expected = str![[r#"
 error: 
@@ -330,7 +328,7 @@ LL | abc
 
 #[test]
 fn issue_130() {
-    let input = Level::ERROR.message("dummy").group(
+    let input = Level::ERROR.header("dummy").group(
         Group::new().element(
             Snippet::source("foo\nbar\nbaz")
                 .origin("file/path")
@@ -358,7 +356,7 @@ fn unterminated_string_multiline() {
 a\"
 // ...
 ";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -382,7 +380,7 @@ error:
 #[test]
 fn char_and_nl_annotate_char() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -405,7 +403,7 @@ error:
 #[test]
 fn char_eol_annotate_char() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -427,7 +425,7 @@ error:
 
 #[test]
 fn char_eol_annotate_char_double_width() {
-    let snippets = Level::ERROR.message("").group(
+    let snippets = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source("こん\r\nにちは\r\n世界")
                 .origin("<current file>")
@@ -452,7 +450,7 @@ error:
 #[test]
 fn annotate_eol() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -475,7 +473,7 @@ error:
 #[test]
 fn annotate_eol2() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -498,7 +496,7 @@ error:
 #[test]
 fn annotate_eol3() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -521,7 +519,7 @@ error:
 #[test]
 fn annotate_eol4() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -543,7 +541,7 @@ error:
 
 #[test]
 fn annotate_eol_double_width() {
-    let snippets = Level::ERROR.message("").group(
+    let snippets = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source("こん\r\nにちは\r\n世界")
                 .origin("<current file>")
@@ -568,7 +566,7 @@ error:
 #[test]
 fn multiline_eol_start() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -592,7 +590,7 @@ error:
 #[test]
 fn multiline_eol_start2() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -616,7 +614,7 @@ error:
 #[test]
 fn multiline_eol_start3() {
     let source = "a\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -639,7 +637,7 @@ error:
 
 #[test]
 fn multiline_eol_start_double_width() {
-    let snippets = Level::ERROR.message("").group(
+    let snippets = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source("こん\r\nにちは\r\n世界")
                 .origin("<current file>")
@@ -665,7 +663,7 @@ error:
 #[test]
 fn multiline_eol_start_eol_end() {
     let source = "a\nb\nc";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -690,7 +688,7 @@ error:
 #[test]
 fn multiline_eol_start_eol_end2() {
     let source = "a\r\nb\r\nc";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -715,7 +713,7 @@ error:
 #[test]
 fn multiline_eol_start_eol_end3() {
     let source = "a\r\nb\r\nc";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -740,7 +738,7 @@ error:
 #[test]
 fn multiline_eol_start_eof_end() {
     let source = "a\r\nb";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -764,7 +762,7 @@ error:
 #[test]
 fn multiline_eol_start_eof_end_double_width() {
     let source = "ん\r\nに";
-    let input = Level::ERROR.message("").group(
+    let input = Level::ERROR.header("").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("file/path")
@@ -788,7 +786,7 @@ error:
 #[test]
 fn two_single_line_same_line() {
     let source = r#"bar = { version = "0.1.0", optional = true }"#;
-    let input = Level::ERROR.message("unused optional dependency").group(
+    let input = Level::ERROR.header("unused optional dependency").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("Cargo.toml")
@@ -825,7 +823,7 @@ this is another line
 so is this
 bar = { version = "0.1.0", optional = true }
 "#;
-    let input = Level::ERROR.message("unused optional dependency").group(
+    let input = Level::ERROR.header("unused optional dependency").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(4)
@@ -864,7 +862,7 @@ this is another line
 so is this
 bar = { version = "0.1.0", optional = true }
 "#;
-    let input = Level::ERROR.message("unused optional dependency").group(
+    let input = Level::ERROR.header("unused optional dependency").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(4)
@@ -912,7 +910,7 @@ so is this
 bar = { version = "0.1.0", optional = true }
 this is another line
 "#;
-    let input = Level::ERROR.message("unused optional dependency").group(
+    let input = Level::ERROR.header("unused optional dependency").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(4)
@@ -963,7 +961,7 @@ error: unused optional dependency
 #[test]
 fn origin_correct_start_line() {
     let source = "aaa\nbbb\nccc\nddd\n";
-    let input = Level::ERROR.message("title").group(
+    let input = Level::ERROR.header("title").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("origin.txt")
@@ -989,7 +987,7 @@ error: title
 #[test]
 fn origin_correct_mid_line() {
     let source = "aaa\nbbb\nccc\nddd\n";
-    let input = Level::ERROR.message("title").group(
+    let input = Level::ERROR.header("title").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("origin.txt")
@@ -1020,7 +1018,7 @@ error: title
 fn two_suggestions_same_span() {
     let source = r#"    A.foo();"#;
     let input_new = Level::ERROR
-        .message("expected value, found enum `A`")
+        .header("expected value, found enum `A`")
         .id("E0423")
         .group(
             Group::new().element(
@@ -1088,7 +1086,7 @@ fn main() {
 }"#;
     let input_new =
         Level::ERROR
-            .message("no method named `pick` found for struct `Chaenomeles` in the current scope")
+            .header("no method named `pick` found for struct `Chaenomeles` in the current scope")
             .id("E0599")
             .group(
                 Group::new().element(
@@ -1148,7 +1146,7 @@ fn single_line_non_overlapping_suggestions() {
     let source = r#"    A.foo();"#;
 
     let input_new = Level::ERROR
-        .message("expected value, found enum `A`")
+        .header("expected value, found enum `A`")
         .id("E0423")
         .group(
             Group::new().element(
@@ -1190,7 +1188,7 @@ LL +     (A::Tuple()).bar();
 fn single_line_non_overlapping_suggestions2() {
     let source = r#"    ThisIsVeryLong.foo();"#;
     let input_new = Level::ERROR
-        .message("Found `ThisIsVeryLong`")
+        .header("Found `ThisIsVeryLong`")
         .id("E0423")
         .group(
             Group::new().element(
@@ -1239,7 +1237,7 @@ fn multiple_replacements() {
 "#;
 
     let input_new = Level::ERROR
-        .message("cannot borrow `*self` as mutable because it is also borrowed as immutable")
+        .header("cannot borrow `*self` as mutable because it is also borrowed as immutable")
         .id("E0502")
         .group(
             Group::new().element(
@@ -1323,7 +1321,7 @@ fn main() {
 }"#;
 
     let input_new = Level::ERROR
-        .message("cannot borrow `chars` as mutable more than once at a time")
+        .header("cannot borrow `chars` as mutable more than once at a time")
         .id("E0499")
         .group(
             Group::new().element(
@@ -1407,7 +1405,7 @@ struct Foo {
 fn main() {}"#;
 
     let input_new = Level::ERROR
-        .message("failed to resolve: use of undeclared crate or module `st`")
+        .header("failed to resolve: use of undeclared crate or module `st`")
         .id("E0433")
         .group(
             Group::new().element(
@@ -1489,7 +1487,7 @@ where
 fn main() {}"#;
 
     let input_new = Level::ERROR
-        .message("the size for values of type `T` cannot be known at compilation time")
+        .header("the size for values of type `T` cannot be known at compilation time")
         .id("E0277")
         .group(
             Group::new().element(
@@ -1558,7 +1556,7 @@ and where
 
 fn main() {}"#;
     let input_new = Level::ERROR
-        .message("the size for values of type `T` cannot be known at compilation time")
+        .header("the size for values of type `T` cannot be known at compilation time")
         .id("E0277")
         .group(Group::new().element(Snippet::source(source)
             .line_start(1)
@@ -1663,7 +1661,7 @@ zappy
 "#;
 
     let input_new = Level::ERROR
-        .message("the size for values of type `T` cannot be known at compilation time")
+        .header("the size for values of type `T` cannot be known at compilation time")
         .id("E0277")
         .group(
             Group::new()
@@ -1731,7 +1729,7 @@ fn main() {
 "#;
 
     let input_new = Level::ERROR
-        .message("type mismatch resolving `<Result<Result<(), Result<Result<(), Result<Result<(), Option<{integer}>>, ...>>, ...>>, ...> as Future>::Error == Foo`")
+        .header("type mismatch resolving `<Result<Result<(), Result<Result<(), Result<Result<(), Option<{integer}>>, ...>>, ...>>, ...> as Future>::Error == Foo`")
         .id("E0271")
         .group(Group::new().element(Snippet::source(source)
             .line_start(4)
@@ -1819,7 +1817,7 @@ fn main() {
 "#;
 
     let input_new = Level::ERROR
-        .message("type mismatch resolving `<Result<Result<(), Result<Result<(), Result<Result<(), Option<{integer}>>, ...>>, ...>>, ...> as Future>::Error == Foo`")
+        .header("type mismatch resolving `<Result<Result<(), Result<Result<(), Result<Result<(), Option<{integer}>>, ...>>, ...>>, ...> as Future>::Error == Foo`")
         .id("E0271")
         .group(Group::new().element(Snippet::source(source)
             .line_start(4)
@@ -1972,7 +1970,7 @@ fn main() {
 "#;
 
     let input_new = Level::ERROR
-        .message("mismatched types")
+        .header("mismatched types")
         .id("E0308")
         .group(Group::new().element(
             Snippet::source(source)
@@ -2056,7 +2054,7 @@ fn main() {
 "#;
 
     let input_new = Level::ERROR
-        .message("mismatched types")
+        .header("mismatched types")
         .id("E0308")
         .group(Group::new().element(
             Snippet::source(source)
@@ -2124,7 +2122,7 @@ LL │ ┃ )>>) {}
 #[test]
 fn unicode_cut_handling() {
     let source = "version = \"0.1.0\"\n# Ensure that the spans from toml handle utf-8 correctly\nauthors = [\n    { name = \"Z\u{351}\u{36b}\u{343}\u{36a}\u{302}\u{36b}\u{33d}\u{34f}\u{334}\u{319}\u{324}\u{31e}\u{349}\u{35a}\u{32f}\u{31e}\u{320}\u{34d}A\u{36b}\u{357}\u{334}\u{362}\u{335}\u{31c}\u{330}\u{354}L\u{368}\u{367}\u{369}\u{358}\u{320}G\u{311}\u{357}\u{30e}\u{305}\u{35b}\u{341}\u{334}\u{33b}\u{348}\u{34d}\u{354}\u{339}O\u{342}\u{30c}\u{30c}\u{358}\u{328}\u{335}\u{339}\u{33b}\u{31d}\u{333}\", email = 1 }\n]\n";
-    let input = Level::ERROR.message("title").group(
+    let input = Level::ERROR.header("title").group(
         Group::new().element(
             Snippet::source(source)
                 .fold(false)
@@ -2150,7 +2148,7 @@ error: title
 fn unicode_cut_handling2() {
     let source = "/*这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。*/?";
     let input = Level::ERROR
-        .message("expected item, found `?`")
+        .header("expected item, found `?`")
         .group(
             Group::new().element(
                 Snippet::source(source)
@@ -2177,7 +2175,7 @@ error: expected item, found `?`
 fn unicode_cut_handling3() {
     let source = "/*这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。这是宽的。*/?";
     let input = Level::ERROR
-        .message("expected item, found `?`")
+        .header("expected item, found `?`")
         .group(
             Group::new().element(
                 Snippet::source(source)
@@ -2204,7 +2202,7 @@ error: expected item, found `?`
 fn unicode_cut_handling4() {
     let source = "/*aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa*/?";
     let input = Level::ERROR
-        .message("expected item, found `?`")
+        .header("expected item, found `?`")
         .group(
             Group::new().element(
                 Snippet::source(source)
@@ -2236,7 +2234,7 @@ fn main() {
 //~^ ERROR mismatched types
 }
 "##;
-    let input = Level::ERROR.message("mismatched types").id("E0308").group(
+    let input = Level::ERROR.header("mismatched types").id("E0308").group(
         Group::new().element(
             Snippet::source(source)
                 .origin("$DIR/non-whitespace-trimming-unicode.rs")
@@ -2281,7 +2279,7 @@ fn main() {
 }
 "##;
     let input = Level::ERROR
-        .message("cannot add `&str` to `&str`")
+        .header("cannot add `&str` to `&str`")
         .id("E0369")
         .group(
             Group::new()
@@ -2348,7 +2346,7 @@ fn foo() {
 "##;
     let bin_source = "�|�\u{0002}!5�cc\u{0015}\u{0002}�Ӻi��WWj�ȥ�'�}�\u{0012}�J�ȉ��W�\u{001e}O�@����\u{001c}w�V���LO����\u{0014}[ \u{0003}_�'���SQ�~ذ��ų&��-\t��lN~��!@␌ _#���kQ��h�\u{001d}�:�\u{001c}\u{0007}�";
     let input = Level::ERROR
-        .message("couldn't read `$DIR/not-utf8.bin`: stream did not contain valid UTF-8")
+        .header("couldn't read `$DIR/not-utf8.bin`: stream did not contain valid UTF-8")
         .group(
             Group::new().element(
                 Snippet::source(source)
diff --git a/tests/rustc_tests.rs b/tests/rustc_tests.rs
index 7a795db..6998629 100644
--- a/tests/rustc_tests.rs
+++ b/tests/rustc_tests.rs
@@ -2,7 +2,7 @@
 //!
 //! [parser-tests]: https://github.com/rust-lang/rust/blob/894f7a4ba6554d3797404bbf550d9919df060b97/compiler/rustc_parse/src/parser/tests.rs
 
-use annotate_snippets::{level::Level, AnnotationKind, Group, Origin, Renderer, Snippet};
+use annotate_snippets::{AnnotationKind, Group, Level, Origin, Renderer, Snippet};
 
 use snapbox::{assert_data_eq, str};
 
@@ -12,7 +12,7 @@ fn ends_on_col0() {
 fn foo() {
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -42,7 +42,7 @@ fn foo() {
 
   }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -74,7 +74,7 @@ fn foo() {
   X2 Y2
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -117,7 +117,7 @@ fn foo() {
   Y1 X1
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -161,7 +161,7 @@ fn foo() {
   X3 Y3 Z3
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -205,7 +205,7 @@ fn foo() {
   X2 Y2 Z2
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -252,7 +252,7 @@ fn foo() {
   X2 Y2 Z2
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -300,7 +300,7 @@ fn foo() {
   X3 Y3 Z3
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -350,7 +350,7 @@ fn foo() {
   X3 Y3 Z3
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -394,7 +394,7 @@ fn foo() {
   X3 Y3 Z3
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -437,7 +437,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -470,7 +470,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -502,7 +502,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -537,7 +537,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -571,7 +571,7 @@ fn foo() {
   a  bc  d
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -605,7 +605,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -633,7 +633,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -662,7 +662,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -701,7 +701,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -732,7 +732,7 @@ fn foo() {
   a { b { c } d }
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -772,7 +772,7 @@ fn foo() {
   X3 Y3 Z3
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -832,7 +832,7 @@ fn foo() {
   X3 Y3 Z3
 }
 "#;
-    let input = Level::ERROR.message("foo").group(
+    let input = Level::ERROR.header("foo").group(
         Group::new().element(
             Snippet::source(source)
                 .line_start(1)
@@ -887,7 +887,7 @@ fn issue_91334() {
 fn f(){||yield(((){),
 "#;
     let input = Level::ERROR
-        .message("this file contains an unclosed delimiter")
+        .header("this file contains an unclosed delimiter")
         .group(
             Group::new().element(
                 Snippet::source(source)
@@ -958,7 +958,7 @@ fn main() {
 }
 "#;
     let input = Level::ERROR
-        .message("`break` with value from a `while` loop")
+        .header("`break` with value from a `while` loop")
         .id("E0571")
         .group(
             Group::new().element(
@@ -1168,7 +1168,7 @@ fn nsize() {
 "#;
     let input =
         Level::ERROR
-            .message("`V0usize` cannot be safely transmuted into `[usize; 2]`")
+            .header("`V0usize` cannot be safely transmuted into `[usize; 2]`")
             .id("E0277")
             .group(
                 Group::new().element(
@@ -1254,7 +1254,7 @@ fn main() {
 }
 "#;
     let input = Level::ERROR
-        .message("`&[u8; 0]` cannot be safely transmuted into `&[u16; 0]`")
+        .header("`&[u8; 0]` cannot be safely transmuted into `&[u16; 0]`")
         .id("E027s7")
         .group(
             Group::new().element(
@@ -1323,7 +1323,7 @@ fn g() {
 fn main() {}
 "#;
     let input = Level::ERROR
-        .message("expected function, found `{integer}`")
+        .header("expected function, found `{integer}`")
         .id("E0618")
         .group(
             Group::new().element(
@@ -1414,7 +1414,7 @@ macro_rules! outer_macro {
 outer_macro!(FirstStruct, FirstAttrStruct);
 "#;
     let input = Level::WARNING
-        .message("non-local `macro_rules!` definition, `#[macro_export]` macro should be written at top level module")
+        .header("non-local `macro_rules!` definition, `#[macro_export]` macro should be written at top level module")
         .group(
             Group::new()
                 .element(
@@ -1547,7 +1547,7 @@ macro_rules! inline {
 }
 "#;
     let input = Level::ERROR
-        .message("can't call method `pow` on ambiguous numeric type `{integer}`")
+        .header("can't call method `pow` on ambiguous numeric type `{integer}`")
         .id("E0689")
         .group(
             Group::new().element(
@@ -1611,7 +1611,7 @@ fn main() {}
 "#;
 
     let input = Level::ERROR
-        .message("type annotations needed")
+        .header("type annotations needed")
         .id("E0282")
         .group(
             Group::new().element(
@@ -1717,7 +1717,7 @@ fn main() {}
 "##;
 
     let input = Level::ERROR
-        .message(
+        .header(
             "non-exhaustive patterns: `NonEmptyEnum5::V1`, `NonEmptyEnum5::V2`, `NonEmptyEnum5::V3` and 2 more not covered"
         )
         .id("E0004")
@@ -1819,7 +1819,7 @@ fn main() {
 }
 "#;
     let input = Level::ERROR
-        .message("the trait alias `EqAlias` is not dyn compatible")
+        .header("the trait alias `EqAlias` is not dyn compatible")
         .id("E0038")
         .group(
             Group::new().element(