What is missing in the css.

The first thing that is very, very lacking is variables or definitions. There are often such cases when a customer looks at a site, thinks, and then gives out something in the spirit of “let's make everything blue on the site a little bit yellower, and everything green is slightly redder”. And the fun went on ... You can, of course, make one class in which only the color will be defined, and set its elements in addition to the main class, but somehow I don’t really like it. First, it turns out piling up, and secondly, there will be at least three such classes (for color, border and background).
And not enough indents, not changing the size. And much is not enough. Because of this, it is often necessary to resort to not very beautiful and non-obvious solutions.
You can still say about a few background drawings, about rounded corners.
But most importantly, what is missing is documentation. Yes, there is no mistake in my statement. Documentation is sorely lacking. Whoever disagrees with me on this, I recommend reading the radio magazines for the 80th and beginning of the 90s. But those who do not agree with me after that, I ask you to show real good documentation. So far, the best I've managed to find is www.htmlbook.ru