Regex Editor & Tester

Matches a CSS-style identifier at the start of a line: an optional leading colon (as in pseudo-classes like :hover) followed by one or more letters/underscores, then any combination of letters, digits, underscores, or hyphens. The i flag makes it accept upper and lowercase letters, while the m flag anchors the match to the beginning of each line. Useful for validating or extracting CSS class names, IDs, and selector identifiers from stylesheets.