if i use

<style type=text/css>
body
{
scrollbar-track-color: #FFFFFF;
scrollbar-face-color: #FFFFFF;
scrollbar-shadow-color: #FFFFFF;
scrollbar-highlight-color: #FFFFFF;
scrollbar-3dlight-color: #FFFFFF;
scrollbar-darkshadow-color: #FFFFFF;
scrollbar-arrow-color: #00EEEE;}
</style>

what code can i add to make the #FFFFFF (white parts) semi-transparent clear?

with what? an iframe?

if so, put that scrollbar code on the page that opens INSIDE the iframe and change #FFFFF to a hexcode that you don't use in your whole layout, since white is a very risky colour to use.

then add this in your <iframe> tag:

style="filter: chroma(color=#COLOR);"

and make sure the #COLOR matches the hexcode you want to be transparent in the scrollbar.

Note: this code is IE only

love,
Mirna

also, you must make the color that is going to be transparent a color that isnt in your layout otherwise everything that is that color will be transparent