Custom CSS Scrollbar for Firefox

As of late 2018, there is now limited customization available in Firefox!

See these answers:

• https://stackoverflow.com/a/54101063/405015
• https://stackoverflow.com/a/53739309/405015

And this for background info: https://bugzilla.mozilla.org/show_bug.cgi?id=1460109

There's no Firefox equivalent to ::-webkit-scrollbar and friends.

You'll have to stick with JavaScript.

Plenty of people would like this feature, see: https://bugzilla.mozilla.org/show_bug.cgi?id=77790

As far as JavaScript replacements go, you can try:

• https://github.com/mdbootstrap/perfect-scrollbar
• https://github.com/Grsmto/simplebar
• https://github.com/vitch/jScrollPane

Firefox 64 adds support for the spec draft CSS Scrollbars Module Level 1, which adds two new properties of scrollbar-width and scrollbar-color which give some control over how scrollbars are displayed.

You can set scrollbar-color to one of the following values (descriptions from MDN):

• auto Default platform rendering for the track portion of the scrollbar, in the absence of any other related scrollbar color properties.
• <color> <color> Applies the first color to the scrollbar thumb, the second to the scrollbar track.

Previously the spec included dark and light values what were not implemented in Firefox. These values have since been removed from the spec.

On stock Android with mobile Firefox the thumb can be colored, but there is no track to color.

Additionally in macOS Firefox version prior to 99.0, the auto-hiding semi-transparent scrollbars that are the macOS default could not be styled by these rules. As of Firefox 99.0 all macOS scrollbar modes (configured under System Preferences > Show Scroll Bars) can be colored.

Visual Demo:

.scroll {
  width: 20%;
  height: 100px;
  border: 1px solid grey;
  overflow: scroll;
  display: inline-block;
}
.scroll-color-auto {
  scrollbar-color: auto;
}
.scroll-color-colors {
  scrollbar-color: orange lightyellow;
}

<div class="scroll scroll-color-auto">
  <p>auto</p><p>auto</p><p>auto</p><p>auto</p><p>auto</p><p>auto</p>
</div>

<div class="scroll scroll-color-colors">
  <p>colors</p><p>colors</p><p>colors</p><p>colors</p><p>colors</p><p>colors</p>
</div>

You can set scrollbar-width to one of the following values (descriptions from MDN):

• auto The default scrollbar width for the platform.
• thin A thin scrollbar width variant on platforms that provide that option, or a thinner scrollbar than the default platform scrollbar width.
• none No scrollbar shown, however the element will still be scrollable.

You can also set a specific length value, according to the spec. Both thin and a specific length may not do anything on all platforms, and what exactly it does is platform-specific. In particular, Firefox doesn't appear to be currently support a specific length value (this comment on their bug tracker seems to confirm this). The thin keywork does appear to be well-supported however, with macOS and Windows support at-least.

On stock Android with mobile Firefox the auto width thumb is already rather thin, and thin does not make it thinner.

It's probably worth noting that the length value option and the entire scrollbar-width property are being considered for removal in a future draft, and if that happens this particular property may be removed from Firefox in a future version.

Visual Demo:

.scroll {
  width: 30%;
  height: 100px;
  border: 1px solid grey;
  overflow: scroll;
  display: inline-block;
}
.scroll-width-auto {
  scrollbar-width: auto;
}
.scroll-width-thin {
  scrollbar-width: thin;
}
.scroll-width-none {
  scrollbar-width: none;
}

<div class="scroll scroll-width-auto">
<p>auto</p><p>auto</p><p>auto</p><p>auto</p><p>auto</p><p>auto</p>
</div>

<div class="scroll scroll-width-thin">
<p>thin</p><p>thin</p><p>thin</p><p>thin</p><p>thin</p><p>thin</p>
</div>

<div class="scroll scroll-width-none">
<p>none</p><p>none</p><p>none</p><p>none</p><p>none</p><p>none</p>
</div>