CSS: bad parts

There is a famous book (at least it was some time ago), by the person who brought us JSON - JavaScript: good parts. It basically teaches which part of the languages are nice to use and won’t get you in a trouble. Book was published way before ES6 and recent goodness. It was helpfull at the time.

(Image source: reddit)

I had a thought: what if we can write down bad parts - things that you should avoid - for CSS.

  • Global styles. Whenever I use styling based on tag names or use nested selectors I find conflict in styles eventually. Instead we can use unique class names for each element. This approach requires some tooling (for example, CSS Modules) or atomic styles.
  • Margins. See Margin considered harmful.
  • Z-index. Whenever you start using z-index, eventually you will get z-index: 999999999 or conflicting items (for example, custom select vs modal). Instead we can rely on order of elements in the DOM. See Z Index Wars.

What else would you recommend to avoid?

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