How can I do width = 100% - 100px in CSS?

Question

In CSS, how can I do something like this:

width: 100% - 100px;

I guess this is fairly simple but it is a bit hard to find examples showing

Answer 1

You can look into using LESS, which is a JavaScript file that pre-processes your CSS so you can include logic and variables into your CSS. So for your example, in LESS you would write width: 100% - 100px; to achieve exactly what you wanted :)