Frequently Asked Questions
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使用していないクラスタグを検出してくれるWEBサービス「Unused CSS」

Service Features

What are the checkboxes below the download button for?

Those elements are the css selectors. The ones that aren't checked are not used and won't be present in the new CSS file when you click download. If you want to keep a selector that's unchecked, just click it and it'll be available in the CSS file.

Why are some selectors are incorrectly marked as unused?

This can happen when our crawler was unable to explore some of your pages. You can enable authenticated crawling to crawl more pages or add a list of pages to explore if you believe they were not discovered. You may also manually mark the selectors you want to keep and then click download.

How is the javascript analysis working?

In order to check if some rules are used in the javascript scripts, all the javascript files are fetched. CSS classes and identifiers are searched in the files using regexps. When a match is found, the rule is marked as used. The javascript is also evaluated using the PhantomJS browser. This way we are able to discover DOM elements created by javascript.

Are the CSS media queries supported?

All media queries sections in your CSS files are included in the exploration and will be optimized. Flexible designs, like bootstrap framework, are supported.

Are the html style elements explored?

The styles defined in the html style element won't be cleaned. We encourage you to put those styles in separate CSS files if you want to removed the unused rules. However, if you import css files in a style element, they will be cleaned.

Site exploration (crawling)

How can I control the crawling process?

There are multiple options to control the crawling of your site. You can create a page with a list of links you absolutely want to crawl and point our tool to this page. The links of the page will be crawled first and then the rest of the site will be explored using breadth first exploration. You can also create a blacklist for pages you don't want to crawl. That option is available on your site settings. Link that are outside of the sub-domain provided (ie. will not be explored. Finally you can provide a list of links that will be used to start the exploration in the site settings page (Advanced options).

Can I remove the unused CSS selectors on just one page?

Yes you can do that. Once you have an account, you can change the site exploration settings. There's a checkbox if you want to clean just one page.

Is it possible to use this tool on an intranet website?

It is not possible to use our service on intranet websites. The site has to be accessible from the internet.

Can I explore pages behind a login form?

Our service allows you to provide a username and password. They are inserted in your login form to begin the authenticated exploration. It will enable our crawler to explore pages that require authentication.

How are the pages explored?

The tool will first collect the links (l1, l2... ln) available on the page you provide. Then it will open the page l1 and collect all the links of that page. Then it will do the same for l2 and all the other links available. It's a breadth first search.

Can the crawler submit forms, how are links discovered?

The crawler will only explore pages available in links (HREF attribute of A elements) and will not do any HTTP POST requests or submit forms (except for your login form if you have enabled that option). You may however customize the crawling process in the site settings by providing a list of links to explore.

Some CSS files are sent only on mobile devices?

If you have a special set of CSS files that are just sent when you browse using a mobile device, you may want to customize the crawler user agent. By default the crawler is identifying itself as a desktop browser. You can change the user agent to an arbitrary string like "Mozilla/5.0 (iPhone; CPU iPhone OS 6_1_4 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10B350 Safari/8536.25".

Can I use this service with my WordPress website?

Yes, our service is compatible with WordPress websites. Some users have reported that deactivating the plugin iThemes Security (formerly Better WP Security) during the exploration process yields better results. You may also want to temporarily deactivate any CSS compression plugins.

Account management

How do I get an account?

To create an account you have to:
- go to the home page
- type the address of the site you want to check in the form
- click detect unused css rules
- on the new page, at the bottom of the page, type your email address and submit

After around 1 hour or less, you will get an email. Then you will be able to view and download the clean CSS file.

How can I remove my account?

You may remove your account at any time using the "Delete my account" link on the settings page.


What's a CSS selector?

A CSS selectors determine which style rules apply to the elements of your html document. For example, in "h1 em { color: blue }", "h1 em" is the selector.

You can read more about selectors here

What's a CSS rule?

A CSS rule is a selector and a declaration. The declaration specifies a bunch of style effects. For example, in "i { color: blue; }", "i" is the selector and "{ color: blue; }" is the declaration.

What is a one level deep exploration?

It means that we will check the page you specify plus all the pages that have a link on this page. If you want to explore more pages, you need to upgrade your account.