gecko/mobile/xul/themes/core/header.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/. */

body {
  font-family: helvetica,arial,clean,sans-serif;
  color: #69645c;
  background: white url("images/aboutBackground.jpg") top center repeat-x;
}

#wrapper {
  max-width: 600px;
  margin: 0 auto;
}