CSS - Cannot get rid of margin

My problem is that i have a header that is suppose to take up the whole top of the page but for some reason there is a margin on both sides.

My Css:

#top_bar{
    background-color:#000;
    height: 80px;
    left: 0px;
    right: 0px;
    margin-left: 0px;
    margin-right: 0px;
    position: relative;
    top: -10px;
    width: 100%;
    c开发者_如何学编程olor:#FFF;
}

Most likely, this stems from the default margin/padding of body. Try adding

html,body {padding:0; margin:0;}