Is it possible to change the scroll bar color in Windows 8?

Often when I'm browsing a web page with a lot of content, the scroll bar is hard to find because the contrast between the position of the clickable part and the background is low.

It would be great if there was a way for me to change the color of the clickable part of the scroll bar so that I could see it better. Is this possible?

The scrollbar color is defined by the Windows theme.

For browsers you can use a custom CSS. In your case, for Google Chrome you can install extension 'Stylish' and add a new style with the following code:

body {
    position: absolute;
    top:20px;
    left: 0px;
    bottom: 0px;
    right: 0px;
    padding: 0px; 
    overflow-y: scroll;
    overflow-x: hidden;
}

::-webkit-scrollbar {width: 12px;}
::-webkit-scrollbar-track {
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.3); 
    -webkit-border-radius: 10px;
    border-radius: 10px;
}
::-webkit-scrollbar-thumb {
    -webkit-border-radius: 10px;
    border-radius: 10px;
    background: rgba(255,0,0,0.8); 
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.5); 
}
::-webkit-scrollbar-thumb:window-inactive {background: rgba(255,0,0,0.4); }

Optionally the style can be further improved with:

html { overflow: auto; }