gecko-dev/browser/devtools/markupview/markup-view.css

/* 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/. */

ul {
  list-style: none;
}

ul.children:not([expanded]) {
  display: none;
}

.codebox {
  display: inline-block;
}

.newattr {
  display: inline-block;
  width: 1em;
  height: 1ex;
}

#root {
  margin-right: 80px;
}

/* Preview */

#previewbar {
  position: fixed;
  top: 0;
  right: 0;
  width: 90px;
  background: black;
  border-left: 1px solid #333;
  border-bottom: 1px solid #333;
  overflow: hidden;
}

#preview {
  position: absolute;
  top: 0;
  right: 5px;
  width: 80px;
  height: 100%;
  background-image: -moz-element(#root);
  background-repeat: no-repeat;
}

#previewbar.hide,
#previewbar.disabled {
  display: none;
}

#viewbox {
  position: absolute;
  top: 0;
  right: 5px;
  width: 80px;
  border: 1px dashed #888;
  background: rgba(205,205,255,0.2);
  outline: 1px solid transparent;
}