I thought it would be helpful to consolidate the latest information on scroll bars, CSS, and browser compatibility.
Scroll Bar CSS Support
Currently, there exists no cross-browser scroll bar CSS styling definitions. The W3C article I mention at the end has the following statement and was recently updated (10 Oct 2014):
Some browsers (IE, Konqueror) support the non-standard properties 'scrollbar-shadow-color', 'scrollbar-track-color' and others. These properties are illegal: they are neither defined in any CSS specification nor are they marked as proprietary (by prefixing them with "-vendor-")
Microsoft
As others have mentioned, Microsoft supports scroll bar styling, but only for IE8 and above.
Example:
.TA {
scrollbar-3dlight-color:gold;
scrollbar-arrow-color:blue;
scrollbar-base-color:;
scrollbar-darkshadow-color:blue;
scrollbar-face-color:;
scrollbar-highlight-color:;
scrollbar-shadow-color:
}
Chrome & Safari (WebKit)
Similarly, WebKit now has its own version:
Firefox (Gecko)
As of version 64 Firefox supports scrollbar styling through the properties scrollbar-color
(partially, W3C draft) and scrollbar-width
(W3C draft). Some good information about the implementation can be found in this answer.
Cross-browser Scroll Bar Styling
JavaScript libraries and plug-ins can provide a cross-browser solution. There are many options.
The list could go on. Your best bet is to search around, research, and test the available solutions. I am sure you will be able to find something that will fit your needs.
Prevent Illegal Scroll Bar Styling
Just in case you want to prevent scroll bar styling that hasn't been properly prefixed with "-vendor", this article over at W3C provides some basic instructions. Basically, you'll need to add the following CSS to a user style sheet associated with your browser. These definitions will override invalid scroll bar styling on any page you visit.
body, html {
scrollbar-face-color: ThreeDFace !important;
scrollbar-shadow-color: ThreeDDarkShadow !important;
scrollbar-highlight-color: ThreeDHighlight !important;
scrollbar-3dlight-color: ThreeDLightShadow !important;
scrollbar-darkshadow-color: ThreeDDarkShadow !important;
scrollbar-track-color: Scrollbar !important;
scrollbar-arrow-color: ButtonText !important;
}
Duplicate or Similar Questions / Source Not Linked Above
Note: This answer contains information from various sources. If a source was used, then it is also linked in this answer.