CSS layout gets smarter with calc()
Didn’t even know about this feature, but it’s brilliant. A quick idea of what you can do:
#bar {
height: calc(10em + 3px);
}
And regarding current support:
The calc() property for lengths is available now in Chrome 19 (Dev channel build) by use of the ’-webkit-calc’ property, in Firefox since version 8 using the ’-moz-calc’ property and in Internet Explorer since version 9 unprefixed.