it would be of great benefit having a CSS preprocessor instead of working with pure CSS. Where I can define some variables, e.g. color, corner radius, border style, ... and can reuse it. without searching and replacing every line.
Like LESS or SASS.
In my case, I am not an designer. For developing I just use some simple css styles, in order it works. But later I would like to finetune my appearance, in order it looks more prefessional. So, when I always have to find replace all my values, it would take ages and is very error prone, because sometimes a special setting should not be replaced.
It's like working with constants in code, instead of hardcoded values. Otherwise, maintaing would become a nightmare.