Review HTTP Content-Type headers, which identify file formats, across web pages and static assets. Find mismatches that can block stylesheets or scripts, and identify server configuration changes needed to serve resources correctly.
Use when auditing server configuration or diagnosing broken resources. Applies to any web server serving HTML, CSS, JS, images, fonts, or other static assets.
Reviews delivery settings for web pages and their related files to investigate why CSS or JavaScript does not load correctly. It checks the HTTP Content-Type header, which tells the browser what kind of file is being delivered. It compares that header with the actual formats of HTML, CSS, JavaScript, and images, identifying mismatches and missing character encoding declarations.
Use it when investigating broken page layouts or scripts that do not run, or when auditing a server’s settings for serving static files. It also checks for files that are returned as text/html even though they are not HTML pages.
Content-Type headers for the main pages and their linked CSS, JavaScript, and images.”charset=utf-8 declaration and the X-Content-Type-Options: nosniff setting.”This work requires inspecting actual HTTP response headers. Fixes belong in the configuration of the server or framework being used. The source names next.config.js as a configuration location for Next.js and similar frameworks.
This overview was written by AI (OpenAI Codex) from the public SKILL.md. Check the original below for the exact behavior.
AI rated this skill on four points using only the contents of its SKILL.md. Stars and popularity are not taken into account.
The total counts each point as A = 25, B = 15, C = 5. Rated by AI (OpenAI Codex) as of Oct 23, 2026. Treat it as a guide and read the original before installing.
Review the instructions the agent will receive before you install.
Incorrect MIME types cause browsers to block stylesheets and scripts (MIME sniffing is disabled by X-Content-Type-Options: nosniff), breaking page rendering and signalling poor site quality to crawlers.
For key pages and their linked resources, inspect the HTTP Content-Type response header. Verify HTML responses use text/html; charset=utf-8, CSS uses text/css, JS uses text/javascript, and images use image/jpeg, image/png, etc.
Update your server configuration to serve each file type with its correct MIME type. Set X-Content-Type-Options: nosniff to prevent browsers from guessing content types. In Next.js and similar frameworks, configure headers in next.config.js.
The Content-Type header tells browsers and crawlers what kind of content is being sent. When it mismatches the actual file type, browsers either block the resource or render it incorrectly—CSS served as text/plain won't be applied, and JavaScript served as text/html may be blocked by strict MIME checking.
For HTML, CSS, and JS assets, check the Content-Type response header. Verify HTML responses include 'charset=utf-8'. Check that X-Content-Type-Options: nosniff is set. Flag any resource returning Content-Type: text/html that is not an HTML page. Check for missing charset declarations on text responses.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
No reviews yet. Tell others what you thought.
No login needed. Share how it worked for you, ask a question, or note where it did not run.
No comments yet. Be the first to write one.
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.