So very quickly web designers started to just hard-code pixel widths into the CSS, removing any dynamic sizing.
For example, on this very page: https://csszengarden.com/ the two-column layout is done by using two overlapping DIVs with a padding on the left one. You could do 3 columns by using the same trick with left padding.
Want to do four columns? Tough. You'd better redesign your whole HTML for that to work. Or just hardcode the sizes.
Of course, this quickly led to interfaces where buttons have text that is cut off. But with lots and lots of useless whitespace padding around them.