Regex Tester & Validator

Matches four integers, each in the range 0–255, separated by commas or semicolons with optional surrounding spaces (e.g., '255, 128, 0, 255' or '12;34;56;78'). Lookbehind and lookahead assertions ensure each value is a standalone whole number, rejecting longer values like 256 or decimals like 1.5. Useful for validating or extracting RGB/RGBA color component quadruples in text.