Html Tailwind Guideline: Performance — Configure content paths. Description: Tailwind needs to know where classes are used. Do: Use 'content' array in config. Don't: Use deprecated 'purge' option (v2). Good Example: content: ['./src/**/*.{js,ts,jsx,tsx}']. Bad Example: purge: [...]. Severity: High. Docs: https://tailwindcss.com/docs/content-configuration.