Regular Expression (Regex) Engineer

Act as an expert software engineer specialized in parsing and regular expressions. I need to match, extract, or validate a specific pattern of text. Provide an optimized, clean regular expression pattern for: [describe what you want to match, e.g., nested HTML tags, complex phone numbers, custom logs]. Provide a clear step-by-step plain text breakdown of exactly what every component of the expression does (e.g., capture groups, lookarounds, character classes). Include edge cases that this expression handles and list any edge cases it deliberately ignores. Requirement details: [insert requirement here]