How much are specificity hacks used?

[LeaVerou]

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By specificity hacks I mean selector rewritings or additions with the sole purpose of increasing or decreasing specificity. Things like:

• [id=foo]
• .foo.foo.foo
• :not(#nonexistent) .actual-selector etc

I suppose BEM could also be considered a specificity hack.

[bradkemper]

Also, html or html body at the beginning of a selector, to just bump it up a little.

[LeaVerou]

Algorithm:

Walk selectors, and count:

• ids in attribute equality
• compound selectors with the same class name more than once
• Descendant selectors with html or :root as the first one.
• Descendant selectors where the first one is :not(#id). This is meaningless in terms of selector logic, so it has to be a specificity hack.
• Selectors that are entirely classes that look like BEM (/^(?=.+--|.+__)[a-z0-9-]+(__[\w-]+)?(--[\w-]+)?$/i) or descendants and such classes