How to make div 100% width when parent tag has padding?

If you give the footer a left and right margin that is a negative amount, of equal size to the padding of the body, then it will counter the body's padding.

body {
    padding-left:10px;
    padding-right:10px;
}
.footer {
    margin-left:-10px;
    margin-right:-10px;
}

Another alternative way can be this : using calc

<div class="parent"> <!--/ Parent div with padding left right -->
    <div class="child">i'm Child div</div>
</body>

CSS

.parent{
   padding:0 20px;
}
.child{
    width:-moz-calc(100% - 40px); <!--/ similar with other browser prefixes -->
    width:calc(100% - 40px);
}

You could apply a negative margin to the inside container to negate the padding

<body style="padding:0 40px">
<div style="width:100%;margin:0 -40px">&nbsp</div>
</body>

Tags:

Html

Css