Selectors Level 4

1. Selector syntax

   Simple selectors, compound selectors and complex selectors.

2. Type, universal, attribute and class selectors

   Attribute presence and value matching.

3. Combinators

   Descendant, child, sibling combinators.

4. Logical combination pseudo-classes

   :is(), :where(), :not() and :has().

5. Structural pseudo-classes

   :nth-child(), :first-child, :empty and :root.

6. Specificity

   Calculating selector specificity.

Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.