CSS Custom Properties Auditor
Paste a block of CSS to find custom properties (--variables) that are declared but never used, and ones used via var() that were never declared.
About this tool
Finds every custom property declaration (--name:, anywhere in the pasted CSS, not just inside :root) and every usage inside a var(--name) call — including ones with a fallback value like var(--name, fallback), where only the variable name is captured. Cross-referencing the two gives you three useful lists: variables that are properly declared and used, variables declared but never referenced anywhere (safe candidates for removal), and variables referenced with var() but never declared anywhere in the pasted CSS — usually a typo or a variable defined in a different stylesheet you didn't paste in.
Commented-out declarations are ignored, variables registered with @property count as declared, and any undeclared variable that has a fallback value is marked, because it won’t break the page: the fallback is used instead. Names are case-sensitive, so --Brand and --brand are different variables.