gecko-dev/themes/modern/global/scrollbars.css

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul); /* set default namespace to XUL */

/********* XP Scrollbar *********/

scrollbar {
   -moz-binding: url("chrome://global/skin/globalBindings.xml#scrollbar");
}

slider {
   -moz-user-focus: ignore;
   -moz-user-select: none;
   background: url("chrome://global/skin/scroll-track-horz-middle.gif") repeat-x;
   height: 15px;
}

slider[align="vertical"] {
   -moz-user-focus: ignore;
   -moz-user-select: none;
   background: url("chrome://global/skin/scroll-track-vert-middle.gif") repeat-y;
   width: 14px;
   border-top: 0px;
   border-bottom: 0px;
}

/* Horizontal Thumb */

thumb {
  -moz-binding: url(chrome://global/skin/globalBindings.xml#thumb-horizontal);
  -moz-user-focus: ignore;
  -moz-user-select: none;
}

.thumb-horz-spring-left {
  background: url(chrome://global/skin/scroll-thumb-horz-left.gif) no-repeat;
  width: 3px;
  height: 14px;
}

.thumb-horz-box-middle {
  background: url(chrome://global/skin/scroll-thumb-horz-expand.gif) repeat-x;
  height: 14px;
}

.thumb-horz-spring-right {
  background: url(chrome://global/skin/scroll-thumb-horz-right.gif) no-repeat;
  width: 3px;
  height: 14px;
}

.thumb-horz-grippy {
  list-style-image: url(chrome://global/skin/scroll-thumb-horz-grippy.gif);
}

/* Thumb Clicked States */

thumb:active > .thumb-horz-spring-left {
  background: url(chrome://global/skin/scroll-thumb-horz-cl-left.gif) no-repeat;
}

thumb:active > .thumb-horz-box-middle {
  background: url(chrome://global/skin/scroll-thumb-horz-cl-expand.gif) repeat-x;
}

thumb:active > .thumb-horz-spring-right {
  background: url(chrome://global/skin/scroll-thumb-horz-cl-right.gif) no-repeat;
}

thumb:active > .thumb-horz-box-middle > .thumb-horz-grippy {
  list-style-image: url(chrome://global/skin/scroll-thumb-horz-cl-grippy.gif);
}

/* Vertical Thumb */

thumb[align="vertical"] {
  -moz-binding: url(chrome://global/skin/globalBindings.xml#thumb-vertical);
  -moz-user-focus: ignore;
  -moz-user-select: none;
}

.thumb-vert-spring-top {
  background: url(chrome://global/skin/scroll-thumb-vert-top.gif) no-repeat;
  height: 3px;
  width: 14px;
}

.thumb-vert-box-middle {
  background: url(chrome://global/skin/scroll-thumb-vert-expand.gif) repeat-y;
  width: 14px;
}

.thumb-vert-spring-bottom {
  background: url(chrome://global/skin/scroll-thumb-vert-bottom.gif) no-repeat;
  height: 3px;
  width: 14px;
}

.thumb-vert-grippy {
  list-style-image: url(chrome://global/skin/scroll-thumb-vert-grippy.gif);
}

/* Thumb Clicked States */

thumb:active > .thumb-vert-spring-top {
  background: url(chrome://global/skin/scroll-thumb-vert-cl-top.gif) no-repeat;
}

thumb:active > .thumb-vert-box-middle {
  background: url(chrome://global/skin/scroll-thumb-vert-cl-expand.gif) repeat-y;
}

thumb:active > .thumb-vert-spring-bottom {
  background: url(chrome://global/skin/scroll-thumb-vert-cl-bottom.gif) no-repeat;
}

thumb:active > .thumb-vert-box-middle > .thumb-vert-grippy {
  list-style-image: url(chrome://global/skin/scroll-thumb-vert-cl-grippy.gif);
}

/* Scrollbar Buttons */

scrollbarbutton {
  -moz-user-focus: ignore;
  -moz-user-select: none;
  vertical-align: bottom;
  cursor: default;
}

scrollbarbutton[type="decrement"] {
   list-style-image: url("chrome://global/skin/scroll-left.gif")
}

scrollbarbutton[type="decrement"]:hover:active {
   list-style-image: url("chrome://global/skin/scroll-left-clicked.gif")
}

scrollbarbutton[type="decrement"][disabled="true"] {
   list-style-image: url("chrome://global/skin/scroll-left-disabled.gif") 
}

scrollbarbutton[type="increment"] {
   list-style-image: url("chrome://global/skin/scroll-right.gif")
}

scrollbarbutton[type="increment"]:hover:active {
   list-style-image: url("chrome://global/skin/scroll-right-clicked.gif")
}

scrollbarbutton[type="increment"][disabled="true"] {
   list-style-image: url("chrome://global/skin/scroll-right-disabled.gif") 
}

scrollbar[align="vertical"] > scrollbarbutton[type="decrement"] {
   list-style-image: url("chrome://global/skin/scroll-up.gif")
}

scrollbar[align="vertical"] > scrollbarbutton[type="decrement"]:hover:active {
   list-style-image: url("chrome://global/skin/scroll-up-clicked.gif")
}

scrollbar[align="vertical"] > scrollbarbutton[type="decrement"][disabled="true"] {
   list-style-image: url("chrome://global/skin/scroll-up-disabled.gif") 
}

scrollbar[align="vertical"] > scrollbarbutton[type="increment"] {
   list-style-image: url("chrome://global/skin/scroll-down.gif")
}

scrollbar[align="vertical"] > scrollbarbutton[type="increment"]:hover:active {
   list-style-image: url("chrome://global/skin/scroll-down-clicked.gif")
}

scrollbar[align="vertical"] > scrollbarbutton[type="increment"][disabled="true"] {
   list-style-image: url("chrome://global/skin/scroll-down-disabled.gif") 
}