Audit CSS file sizes and loading behavior to find stylesheets that delay page rendering. Confirm the problem with performance measurements, then reduce unnecessary CSS through minification, unused-style removal, or splitting files by page.
Use when auditing slow page loads, heavy assets, or rendering delays related to Optimize CSS file size. Verify the actual bottleneck in DevTools, Lighthouse, or field data before recommending changes.
Review the instructions the agent will receive before you install.
Large CSS files block rendering and increase the time it takes for the browser to construct the CSSOM, leading to a slower First Contentful Paint.
Audit the size of CSS files and identify those exceeding recommended limits (e.g., > 50KB gzipped).
Minify CSS, remove unused styles, and consider splitting large stylesheets into smaller, page-specific files.
Explain how CSS file size affects the critical rendering path and browser performance.
Review the routes, assets, and loading behavior that affect Optimize CSS file size. Flag exact files, requests, or rendering steps that add unnecessary network, CPU, or layout cost, and describe the measurement method used to confirm the issue.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/performance/css-file-size
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Create and review custom 404 pages that help visitors recover from broken or moved links through search and navigation. Check the rendered page and HTTP response so missing content returns a proper 404 status.
Audit or create a dedicated About page that explains a website’s purpose and identifies its people or organization. Review the rendered output and supporting information, including expertise and contact details, to find gaps.
Review and add automated accessibility checks for components, pages, and continuous integration workflows. Use axe-based tools to detect structural and attribute issues, while identifying checks that still need keyboard or screen reader testing.
Review sign-in, registration, multi-factor authentication, and account recovery for accessibility barriers. Find blocked paste, difficult code entry, and inaccessible backup methods, then suggest authentication paths that support password managers, autofill, or device approval.
Review form errors, success messages, and live updates so screen reader users receive important notifications. Check the HTML delivered to the browser, announcement settings, display duration, and dismissal controls, then identify specific elements that need changes.
Review HTML tables so screen reader users can understand how headers and data relate. Check header markup, table descriptions, and merged cells, then identify specific fixes and ways to verify them.