If you are one of those meticulous types who like to follow rules, it
would be better that you do not use the css scrollbar properties. Decorating the scrollbar is possible only in IE browser. You can set colors for all these on a scrollbar using styles. And here are the CSS properties that govern these colors

html {scrollbar-face-color: #FF0000;
scrollbar-shadow-color: #0000FF;
scrollbar-highlight-color: #00FF00;
scrollbar-3dlight-color: #FF00FF;
scrollbar-darkshadow-color: #00FFFF;
scrollbar-track-color: #FFFF00;
scrollbar-arrow-color: #000000;}