gecko-dev/layout/style/viewsource.css

@charset "utf-8";
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

@namespace url(http://www.w3.org/1999/xhtml); /* set default namespace to HTML */

*|*:root {
  background-color: white;
  color: black;
  direction: ltr;
  -moz-control-character-visibility: visible;
}
#viewsource {
  font-family: -moz-fixed;
  font-weight: normal;
  white-space: pre;
  counter-reset: line;
}
#viewsource.wrap {
  white-space: pre-wrap;
  word-wrap: break-word;
}
pre {
  font: inherit;
  color: inherit;
  white-space: inherit; 
  margin: 0 0 0 5ch;
}
pre[id]:before,
span[id]:before {
  content: counter(line) " ";
  counter-increment: line;
  -moz-user-select: none;
  display: inline-block;
  width: 5ch;
  margin: 0 0 0 -5ch;
  text-align: right;
  color: #ccc;
  font-weight: normal;
  font-style: normal;
}
.start-tag {
 color: purple;
 font-weight: bold;
}
.end-tag {
 color: purple;
 font-weight: bold;
}
.comment {
 color: green;
 font-style: italic;
}
.cdata {
 color: #CC0066;
}
.doctype {
 color: steelblue;
 font-style: italic;
}
.pi {
 color: orchid;
 font-style: italic;
}
.entity {
 color:#FF4500;
 font-weight: normal;
}
.text {
  font-weight: normal;
}
.attribute-name {
 color: black;
 font-weight: bold;
}
.attribute-value {
 color: blue;
 font-weight: normal;
}
.markupdeclaration {
 color: steelblue;
 font-style: italic;
}
span:not(.error), a:not(.error) {
 unicode-bidi: embed;
}
span[id] {
 unicode-bidi: -moz-isolate;
}
.error, 
.error > :-moz-any(.start-tag, .end-tag, .comment, .cdata, .doctype, .pi,
                   .entity, .attribute-name, .attribute-value) {
  color: red;
  font-weight: bold;
}