Quickly identify and remove unused CSS selectors from your stylesheet. Optimize your website performance for free with this browser-based CSS cleanup utility.
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Unused CSS Finder Specification
Overview
A high-performance, single-file browser utility designed to help developers clean up their stylesheets. It compares user-provided HTML against CSS to identify selectors that are not being utilized in the DOM.
UI Layout
- Header: Clean, minimalist navigation containing the tool name and a brief instruction subtitle.
- Input Section:
- Two-column layout on desktop, single-column on mobile.
- Left: 'HTML Source Code' textarea with line numbering.
- Right: 'CSS Stylesheet' textarea with line numbering.
- Control Panel: A primary 'Analyze' button, centered, using a vibrant blue primary color. A 'Clear' button for resetting inputs.
- Results Area:
- A detailed results dashboard showing 'Unused Selectors' vs 'Total Selectors'.
- A scrollable, list-view of unused selectors with an option to 'Copy to Clipboard'.
Color Palette
- Primary: Vibrant Blue (#2563eb) for buttons and key actions.
- Background: Clean White (#ffffff) and Soft Gray (#f8fafc) for sections.
- Text: Slate Gray (#334155) for readability.
- Borders: Light Neutral Gray (#e2e8f0).
- Highlights: Pastel Red (#fee2e2) for unused items, Pastel Green (#dcfce7) for analysis success indicators.
Technical Implementation
- Logic:
- Use
DOMParserto handle the HTML input, allowing for robust query selection. - Use Regular Expressions to extract CSS selectors while ignoring media queries and pseudo-classes where appropriate.
- Perform an intersection check: (All CSS Selectors) - (Used CSS Selectors) = Unused CSS.
- Use
- Performance: Ensure processing is asynchronous to keep the UI responsive for large inputs.
- State: Purely in-memory variables. No
localStorage,sessionStorage, or cookies.
Design Standards
- Aesthetic: Modern SaaS look. Use generous whitespace, rounded corners (8px radius), and soft drop shadows for input fields.
- Animations: Subtle fade-in transition for the results dashboard when it appears. 'Bounce' animation on button click for tactile feedback.
- Responsive: Fluid CSS Grid/Flexbox layout. Ensure textareas scale proportionally with screen width.
- Compatibility: Strictly single-file (HTML/CSS/JS). No external frameworks like React or Vue. Use CDN links for any necessary icons (e.g., FontAwesome) or CSS resets (e.g., Tailwind via CDN or custom minimal CSS).
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Frequently Asked Questions
Everything you need to know about using this application.
How does this unused CSS finder work?
This tool operates by taking your provided HTML and CSS code and processing it entirely within your browser environment. It utilizes a robust CSS parser to extract all defined classes, IDs, and element selectors from your stylesheet string. Simultaneously, it scans the HTML markup to verify if those extracted selectors are actually present in the DOM structure. If a selector defined in your CSS is not found anywhere in your HTML code, it is flagged as unused, providing you with a list of candidates for removal.
Is my code secure when using this tool?
Yes, your code remains completely secure because this application performs all operations client-side. No data is ever sent, uploaded, or transmitted to an external server or database. Everything happens locally in your web browser. This ensures that sensitive project files or proprietary code remains private and is discarded immediately after you close the browser tab.
What happens to my data after I refresh the page?
Since this tool is designed for maximum privacy and security, it does not utilize local storage, cookies, or any persistent memory. Once you refresh the page, all entered HTML and CSS code, along with any analysis results, will be cleared. We recommend copying your results to a clipboard or saving them in your local code editor before leaving or refreshing the page, as there is no retrieval mechanism for previous sessions.
Why is it important to remove unused CSS?
Removing unused CSS is a critical step in optimizing web performance and improving your Core Web Vitals. Unused CSS increases the total file size that a browser must download before it can begin rendering the page, which directly impacts your site's load speed. By pruning these unnecessary styles, you reduce the time required for the browser to parse the stylesheet and build the CSS Object Model (CSSOM). This results in faster First Contentful Paint times and a more efficient user experience overall.
