How to remove borders from images

How to i get rid of those borders in the Social Bookmarks at my site…
Those 3 images in my blog Facebook, Twitter and Feeds..

I would like to delete that black border

http://bestfinecomputers.com

I have this in my Stylesheet..

/* ================================================================
IMAGE SETTINGS
=================================================================== */

img.centered {
display: block;
margin-left: auto;
margin-right: auto;
padding: 0px;
}

img.alignnone {
padding: 0px;
margin: 0px 0px 10px 0px;
display: inline;
}

img.alignright {
padding: 0px;
margin: 5px 0px 20px 15px;
display: inline;
}

img.alignleft {
padding: 0px;
margin: 5px 20px 15px 0px;
display: inline;
}

img.alignleft {
padding: 0px;
margin: 5px 20px 15px 0px;
display: inline;
}

.alignright {
float: right;
}

.alignleft {
float: left;
}

.wp-caption {
margin: 0px;
padding: 0px;
}

.wp-caption img {
margin: 0px 0px 10px 0px;
padding: 0px;
border: 0px;
}

.wp-caption p.wp-caption-text {
margin: 0px;
padding: 5px 0px 0px 0px;

font-size: 10px;
font-style: italic;
font-weight: bold;
line-height: 12px;
}

#imagediv-main {
width: 218px;
margin: 0px 0px 12px 0px;
padding: 0px 0px 0px 0px;
}

#imagediv-cat {
width: 68px;
margin: 0px 0px 12px 0px;
padding: 0px 0px 0px 0px;
}