gecko/toolkit/mozapps/update/content/updates.css

/**
 * General
 */
wizard[description=""] .wizard-header-description {
  display: none;
}

/**
 * Stop animations when they aren't displayed (bug 341749).
 */
#updates:not([currentpageid="checking"]) #checkingProgress,
#updates:not([currentpageid="incompatibleCheck"]) #incompatibleCheckProgress,
#updates:not([currentpageid="downloading"]) #downloadThrobber,
#updates:not([currentpageid="downloading"]) #downloadProgress {
  display: none;
}

/**
 * Remote content displayed in the billboard and license pages.
 */
remotecontent {
  -moz-binding: url("chrome://mozapps/content/update/updates.xml#remotecontent");
  display: -moz-deck;
}

/**
 * Update History Window
 */
update {
  -moz-binding: url("chrome://mozapps/content/update/updates.xml#update");
  display: -moz-box;
  -moz-box-orient: vertical;
}