Learn how the CSS :is(), :where(), and :has() selectors work, with real examples. Master selector grouping, zero-specificity styling, and the CSS parent selector in one practical guide.

Learn how CSS specificity is calculated using the (A,B,C,D) score system. Understand inline styles, IDs, classes, and elements, and why !important breaks everything.

Learn how the CSS cascade works: how origin, specificity, and source order decide which styles apply, how to read specificity scores, when to use !important, and how to predict which CSS rule wins any conflict.