Just use div { padding: 20px; }
and substract 40px
from your original div
width.
Like Philip Wills pointed out, you can also use box-sizing
instead of substracting 40px
:
div {
padding: 20px;
-moz-box-sizing: border-box;
box-sizing: border-box;
}
The -moz-box-sizing
is for Firefox.