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 try this...

width: calc(100% - 100px);

width: calc(100vh - 100px);

vw: viewport width

vh: viewport height