[themes] Changing Style.css doesn't reflect for Internet explorer

I've just changed some background colors and font colors, nothing else. There was header image and i just commented that code and put the code-line for background image :

#header { //background:url(images/header.png) repeat-x; background-color : #B00000; height:100px; margin:0; padding:0; }

.sidebar .block h2 { height:19px; //background:url(images/blockhead.png) no-repeat; background-color : #B00000;//#808080; //#000000 ; color: #fff; //#6C7A8D; font-size:13px; //font-weight:700;

//margin: 10px -8px 8px -5px; padding:4px 2px 4px 6px; }

These are some code segment where i've done small changes.

Thanks, Vishakha