Guide · Agent skill
How to use the CSS File Load Order Checker agent skill
Updated · written with AI from the project's own documentation and checked against our catalogue data
The css-order skill is an agent skill that makes an AI agent review how a page loads its CSS and JavaScript files, and check that stylesheets come before scripts in the document head. This guide explains what the skill does, how to install it, how to trigger it with plain requests, and what to keep in mind before relying on it. By the end you will be able to ask an agent to check a page's head section and understand the fixes it suggests.
CSS File Load Order Checkerthedaviddias/Front-End-Checklist · MIT Download the skill Quick start
- 1Download the ZIP. Get the css-order skill ZIP from this page.
- 2Unzip the skill. Extract it into ~/.claude/skills/ for personal use, or into .claude/skills/ inside a project.
- 3Or upload in the Claude apps. In the Claude apps, go to Settings → Capabilities → Skills and upload the skill.
- 4Ask in plain language. Request a check of CSS and JavaScript order in your page's head section.
- 5Review the findings. Read the agent's explanation of any ordering problems and the suggested fixes.
- 6Apply and re-test. Make the changes you agree with, then check the page in a browser yourself.
What does the css-order skill make the agent do?
The skill covers one rule from the Front-End Checklist: all CSS files should be loaded before JavaScript files in the document head. The agent checks the order, explains why it matters (stylesheets that load late can cause a brief flash of unstyled content, or FOUC), and suggests fixes.
Fixes can include moving files so stylesheets come first, or marking non-critical scripts as async or defer. The skill works from written guidance rather than running tools, so treat it as a review aid, not an automated tester.
- Checks that stylesheets come before scripts in the document head
- Explains why this ordering prevents a flash of unstyled content
- Suggests fixes such as moving files or using async or defer on non-critical scripts
How do you install the css-order skill?
Download the ZIP for the skill from this page and unzip it. You can place the resulting folder in one of two locations: your personal skills folder at ~/.claude/skills/, or a project-specific .claude/skills/ folder inside the project you are working on.
If you use the Claude apps instead, you can upload the skill under Settings → Capabilities → Skills.
- Personal: unzip into ~/.claude/skills/
- Project-only: unzip into .claude/skills/ inside your project
- Claude apps: upload under Settings → Capabilities → Skills
Which files does the skill contain?
The skill folder includes SKILL.md, which holds the skill's instructions, metadata and quick reference, and references/rule.md, which has fuller implementation details and HTML code examples. The agent reads these when the skill is triggered.
- SKILL.md: instructions, quick reference and the check, fix and explain steps
- references/rule.md: full guidance and HTML examples for the document head
How do you trigger the skill with a natural request?
You do not need a special command. The skill is meant for reviewing stylesheets and page head setup, so ask in plain language about CSS and script order, load order, or render-blocking. Mention the file or page you want checked so the agent knows where to look.
The skill's description also covers reviewing component styles and responsive behavior, but it only touches load order in general terms. Be specific about what you want checked.
- "Check whether the CSS files in index.html load before the JavaScript."
- "Why is my page flashing unstyled content on load? Review the head section."
- "Review this project's head tags against the CSS order rule before release."
- "Explain why stylesheets should load before scripts, and suggest where to add defer."
What does a correct document head look like?
The reference file shows stylesheets listed first, a small critical inline style block, and then scripts, with non-critical scripts marked defer. Use it as a comparison when the agent reviews your page.
The example below is taken from references/rule.md and shows the ordering the skill checks for.
<head>
<link rel="stylesheet" href="reset.css">
<link rel="stylesheet" href="main.css">
<link rel="stylesheet" href="components.css">
<style>
/* Critical above-the-fold styles */
.hero { display: block; }
</style>
<script src="critical-polyfills.js"></script>
<script defer src="main.js"></script>
</head>What does the skill need, and what are the safety notes?
The skill lists no requirements. It does not run scripts and does not use the network, so it only reads the content you give it and produces advice. Because it does not run browser or speed tests, its output is not a measurement of your page's real performance.
Review every suggested change before applying it, especially moves that alter script execution order, since async and defer change when scripts run.
- Requires: nothing listed
- Runs scripts: no
- Uses network: no
- Gives advice only; it does not run browser or speed tests
What are good tips for getting useful results?
Give the agent the actual head section or file paths, not just a general question. Ask it to explain its reasoning so you learn the rule and can apply it yourself later. Use it as a checklist step alongside your own testing in a real browser.
- Paste the full head section so the agent can compare ordering line by line
- Ask for the reason behind each suggestion, not only the change
- Re-check the page in a browser after applying fixes
- Keep the skill for head-order questions; use dedicated tools for speed measurement
What people use it for
- Tidying the head section of a landing page so stylesheets load before scripts
- Reviewing a web project against a front-end checklist before a release
- Explaining to a teammate or beginner why stylesheet and script order matters
- Deciding which non-critical scripts could be marked async or defer
Frequently asked questions
How do I install the css-order agent skill?
Download the ZIP from this page and unzip it into ~/.claude/skills/ for personal use, or into .claude/skills/ inside a project. In the Claude apps, you can instead upload it under Settings → Capabilities → Skills.
Does the css-order skill require anything else?
The skill lists no requirements. It does not run scripts and does not use the network.
Is the css-order skill free?
The skill is published under the MIT licence. This page does not state pricing beyond that, so check the licence file in the source for terms.
Can the skill measure my page's speed or find FOUC automatically?
No. The skill works from written guidance and does not run browser or speed tests. It is a review aid that explains ordering and suggests fixes, so confirm results in a real browser.
Does the skill handle complex responsive or layout bugs?
Only in general terms. Its main focus is load order, so for detailed breakpoint or layout problems you will need other review methods.
What is the difference between async and defer?
The skill mentions both as options for non-critical JavaScript that should not block rendering. The reference example marks main.js with defer, and the skill suggests async or defer for scripts that do not need to block the page.
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Our verdict
Use css-order if you are a front-end developer or beginner who wants a clear explanation of why stylesheets should load before scripts, and a quick review of your page head. Pick a different tool if you need real performance measurement or detailed responsive and layout testing, since this skill gives advice without running any tests.
Download the skill