src/theme: import theme from mdBook upstream, filter out what's needed

add buttons for printing, editing, and changing to dark theme
clean up CSS, including improvements to the print theming

Co-authored-by: Érico Nogueira <erico.erc@gmail.com>

book.toml

@@ -6,6 +6,9 @@ title = "Void Linux Handbook"
 
 [output.html]
 theme = "src/theme"
+default-theme = "void-light"
+preferred-dark-theme = "void-dark"
+edit-url-template = "https://github.com/void-linux/void-docs/edit/master/{path}"
 
 [output.html.redirect]
 "/about-this-handbook.html" = "/about/about-this-handbook.html"

src/theme/book.js

@@ -3,6 +3,21 @@
 // Fix back button cache problem
 window.onunload = function () { };
 
+(function theme() {
+    var html = document.querySelector("html");
+    var themeToggleButton = document.getElementById("theme-toggle");
+
+    themeToggleButton.addEventListener('click', function sidebarToggle() {
+        if (html.classList.contains("void-light")) {
+            html.classList.replace("void-light", "void-dark");
+            localStorage.setItem('mdbook-theme', "void-dark");
+        } else {
+            html.classList.replace("void-dark", "void-light");
+            localStorage.setItem('mdbook-theme', "void-light");
+        }
+    });
+})();
+
 (function sidebar() {
     var html = document.querySelector("html");
     var sidebar = document.getElementById("sidebar");