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

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

/* Hide the wizard's header so the size of the billboard can size the window 
   on creation. A custom header will be used in its place when a header is
   needed. */
.wizard-header {
  display: none;
}

/* Display the custom header */
.update-header {
  display: -moz-box !important;
}

/* Custom header implementation based on the Wizard's header. This allows the
   size of the billboard's remotecontent to size the window since it does not
   have an updateheader on the billboard page. */
updateheader {
  -moz-binding: url("chrome://mozapps/content/update/updates.xml#updateheader");
  display: -moz-box;
  -moz-box-orient: horizontal;
}

/* 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;
}