diff --git a/README.md b/README.md
index 18ef317..d9ab5e9 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,7 @@ The [differential_calculus.typ](differential_calculus.typ) ([render](differentia
 #show: thmrules
 
 #set page(width: 16cm, height: auto, margin: 1.5cm)
+#set text(font: "Linux Libertine", lang: "en")
 #set heading(numbering: "1.1.")
 
 #let theorem = thmbox("theorem", "Theorem", fill: rgb("#eeffee"))
@@ -51,8 +52,8 @@ The [differential_calculus.typ](differential_calculus.typ) ([render](differentia
 = Prime numbers
 
 #definition[
-  A natural number is called a _prime number_ if it is greater than 1
-  and cannot be written as the product of two smaller natural numbers.
+  A natural number is called a #highlight[_prime number_] if it is greater
+  than 1 and cannot be written as the product of two smaller natural numbers.
 ]
 #example[
   The numbers $2$, $3$, and $17$ are prime.
@@ -76,6 +77,21 @@ The [differential_calculus.typ](differential_calculus.typ) ([render](differentia
 #corollary[
   There are infinitely many composite numbers.
 ]
-
 ```
 
+
+## Acknowledgements
+
+Thanks to
+
+- [MJHutchinson]("https://github.com/MJHutchinson") for suggesting and
+  implementing the `base_level` and `base: none` features,
+- [rmolinari]("https://github.com/rmolinari") for suggesting and
+  implementing the `separator: ...` feature,
+- [DVDTSB]("https://github.com/DVDTSB") for contributing
+  - the idea of passing named arguments from the theorem directly to the `fmt`
+    function.
+  - the `number: ...` override feature.
+  - the `title: ...` override feature in `thmbox`.
+- The awesome devs of [typst.app]("https://typst.app/") for their
+  support.
diff --git a/basic.pdf b/basic.pdf
index 71a1bc1..7c3bb7a 100644
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diff --git a/basic.png b/basic.png
index 86d132a..6f41037 100644
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diff --git a/basic.typ b/basic.typ
index bb89c3c..55737b3 100644
--- a/basic.typ
+++ b/basic.typ
@@ -26,8 +26,8 @@
 = Prime numbers
 
 #definition[
-  A natural number is called a _prime number_ if it is greater than 1
-  and cannot be written as the product of two smaller natural numbers.
+  A natural number is called a #highlight[_prime number_] if it is greater
+  than 1 and cannot be written as the product of two smaller natural numbers.
 ]
 #example[
   The numbers $2$, $3$, and $17$ are prime.
diff --git a/differential_calculus.pdf b/differential_calculus.pdf
index f67a830..ebb4c6e 100644
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diff --git a/manual.pdf b/manual.pdf
index 63a9681..e667ba8 100644
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diff --git a/manual.typ b/manual.typ
index 9ffa6ab..6bde365 100644
--- a/manual.typ
+++ b/manual.typ
@@ -180,6 +180,18 @@ sets some plainer defaults. You can also write
 
 Note that the last _Lemma_ is _not_ numbered 3.1.2!
 
+You can also override the automatic numbering as follows.
+```typst
+#lemma(number: "42")[
+  The square of any natural number cannot be two more than a multiple of 4.
+]
+```
+#lemma(number: "42")[
+  The square of any natural number cannot be two more than a multiple of 4.
+]
+
+Note that this does _not_ affect the counters either!
+
 
 == Limiting depth
 
@@ -286,9 +298,10 @@ You can go even further and use the `thmenv` function directly. It accepts an
   "Notation",                 // supplement
   none,                       // base - do not attach, count globally
   none,                       // base_level - use the base as-is
-  (name, number, body) => [   // fmt - format content using the environment
-                              // name, number, and body
-    #h(1.2em) *Notation (#number) #name*:
+  (name, number, body, color: black) => [
+                              // fmt - format content using the environment
+                              // name, number, body, and an optional color
+    #text(color)[#h(1.2em) *Notation (#number) #name*]:
     #h(0.2em)
     #body
     #v(0.5em)
@@ -298,14 +311,18 @@ You can go even further and use the `thmenv` function directly. It accepts an
 #notation[
   The variable $p$ is reserved for prime numbers.
 ]
+#notation("for Reals", color: green)[
+  The variable $x$ is reserved for real numbers.
+]
 ```
 #let notation = thmenv(
   "notation",                 // identifier
   "Notation",                 // supplement
   none,                       // base - do not attach, count globally
   none,                       // base_level - use the base as-is
-  (name, number, body) => [   // fmt - format content using the environment name, number, and body
-    #h(1.2em) *Notation (#number) #name*:
+  (name, number, body, color: black) => [
+                              // fmt - format content using the environment name, number, body, and an optional color
+    #text(color)[#h(1.2em) *Notation (#number) #name*]:
     #h(0.2em)
     #body
     #v(0.5em)
@@ -315,6 +332,27 @@ You can go even further and use the `thmenv` function directly. It accepts an
 #notation[
   The variable $p$ is reserved for prime numbers.
 ]
+#notation("for Reals", color: green)[
+  The variable $x$ is reserved for real numbers.
+]
+
+Note that the `color: green` named argument supplied to the theorem
+environment gets passed to the `fmt` function. In general, all extra named
+arguments supplied to the theorem will be passed to `fmt`.
+On the other hand, the positional argument `"for Reals"` will always be
+interpreted as the `name` argument in `fmt`.
+
+```typst
+#lemma(title: "Lem.")[
+  All multiples of 3 greater than 3 are composite.
+]
+```
+#lemma(title: "Lem.")[
+  All multiples of 3 greater than 3 are composite.
+]
+
+Here, we override the `title` (which defaults to the `head`) in the `fmt`
+produced by `thmbox`.
 
 
 == Labels and references <references>
@@ -392,15 +430,20 @@ The `thmenv` function produces a _theorem environment_.
   base,                   // base counter name, can be "heading" or none
   base_level,             // number of base number levels to use
   fmt                     // formatting function of the form
-                          // (name, number, body) -> content
+                          // (name, number, body, ..args) -> content
 ) = { ... }
 ```
 
+The `fmt` function must aceept a theorem `name`, `number`, `body`, and produce
+formatted content. It may also accept additional positional arguments, via
+`args`.
+
 A _theorem environment_ is itself a map of the following form.
 ```typst
 (
-  ..name,                 // name, often used in the title
+  ..args,
   body,                   // body content
+  number: auto,           // number, overrides numbering if present
   numbering: "1.1",       // numbering style, can be a function
   refnumbering: auto,     // numbering style used in references,
                           // defaults to "numbering"
@@ -409,6 +452,11 @@ A _theorem environment_ is itself a map of the following form.
 ) -> content
 ```
 
+Positional arguments in `args` are as follows
+- `name`: The name of the theorem, typically displayed after the title.
+
+All additional named arguments in `args` will be passed on to the associated
+`fmt` function supplied in `thmenv`.
 
 
 == `thmbox` and `thmplain`
@@ -452,8 +500,15 @@ defaults.
 
 = Acknowledgements
 
-Thanks to #link("https://github.com/MJHutchinson")[MJHutchinson] for
-suggesting and implementing the `base_level` and `base: none` features,
-#link("https://github.com/rmolinari")[rmolinari] for suggesting and
-implementing the `separator: ...` feature, and to the awesome devs of
-#link("https://typst.app/")[typst.app] for their support.
+Thanks to
+- #link("https://github.com/MJHutchinson")[MJHutchinson] for suggesting and
+  implementing the `base_level` and `base: none` features,
+- #link("https://github.com/rmolinari")[rmolinari] for suggesting and
+  implementing the `separator: ...` feature,
+- #link("https://github.com/DVDTSB")[DVDTSB] for contributing
+  - the idea of passing named arguments from the theorem directly to the `fmt`
+    function.
+  - the `number: ...` override feature.
+  - the `title: ...` override feature in `thmbox`.
+- The awesome devs of #link("https://typst.app/")[typst.app] for their
+  support.
diff --git a/manual_examples.pdf b/manual_examples.pdf
index 4a50f0f..ee57150 100644
Binary files a/manual_examples.pdf and b/manual_examples.pdf differ
diff --git a/manual_examples.typ b/manual_examples.typ
index 6f02de5..d0ab5a7 100644
--- a/manual_examples.typ
+++ b/manual_examples.typ
@@ -68,7 +68,9 @@ these has been explained in full detail there.
 #lemma[
   The square of any odd number is one more than a multiple of $4$.
 ]
-
+#lemma(number: "42")[
+  The square of any natural number cannot be two more than a multiple of 4.
+]
 
 == Limiting depth
 
@@ -120,8 +122,9 @@ these has been explained in full detail there.
   "Notation",                 // supplement
   none,                       // base - do not attach, count globally
   none,                       // base_level - use the base as-is
-  (name, number, body) => [   // fmt - format content using the environment name, number, and body
-    #h(1.2em) *Notation (#number) #name*:
+  (name, number, body, color: black) => [
+                              // fmt - format content using the environment name, number, body, and an optional color
+    #text(color)[#h(1.2em) *Notation (#number) #name*]:
     #h(0.2em)
     #body
     #v(0.5em)
@@ -131,7 +134,13 @@ these has been explained in full detail there.
 #notation[
   The variable $p$ is reserved for prime numbers.
 ]
+#notation("for Reals", color: green)[
+  The variable $x$ is reserved for real numbers.
+]
 
+#lemma(title: "Lem.")[
+  All multiples of 3 greater than 3 are composite.
+]
 
 == Labels and references <references>
 
diff --git a/theorems.typ b/theorems.typ
index 0046db6..69db8dd 100644
--- a/theorems.typ
+++ b/theorems.typ
@@ -13,24 +13,26 @@
   let global_numbering = numbering
 
   return (
-    ..name,
+    ..args,
     body,
+    number: auto,
     numbering: "1.1",
     refnumbering: auto,
     base: base,
     base_level: base_level
   ) => {
-    if name != none and name.pos().len() > 0 {
-      name = name.pos().first()
-    } else {
-      name = none
+    let name = none
+    if args != none and args.pos().len() > 0 {
+      name = args.pos().first()
     }
     if refnumbering == auto {
       refnumbering = numbering
     }
-    let number = none
     let result = none
-    if not numbering == none {
+    if number == auto and numbering == none {
+      number = []
+    }
+    if number == auto and numbering != none {
       result = locate(loc => {
         return thmcounters.update(thmpair => {
           let counters = thmpair.at("counters")
@@ -79,7 +81,7 @@
     }
     figure(
       result +  // hacky!
-      align(left, fmt(name, number, body)) +
+      align(left, fmt(name, number, body, ..args.named())) +
       figure(none, supplement: none, numbering: none, kind: "thmenv-counter", gap: 0em),  // even more hacky!
       kind: "thmenv",
       outlined: false,
@@ -111,13 +113,15 @@
   if supplement == auto {
     supplement = head
   }
-  let boxfmt(name, number, body) = {
+  let boxfmt(name, number, body, title: auto) = {
     if not name == none {
       name = [ #namefmt(name)]
     } else {
       name = []
     }
-    let title = head
+    if title == auto {
+      title = head
+    }
     if not number == none {
       title += " " + number
     }