What is MIME type "text/css"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

The MIME type text/css tells browsers to process style rules. It defines how HTML elements appear on a page.

Files carrying these rules, like CSS and LESS, instruct browsers on colors, fonts, spacing, and layout.

Style Application: It applies design rules to structure the visual look of web content.
Separation of Concerns: It keeps design separate from HTML, making maintenance easier.
Browser Processing: Browsers use this MIME type to correctly parse and render style sheets.
Responsive Design: It supports layouts that adjust across diverse devices.

Using text/css ensures that web pages display as intended. For more details, see MIME types on MDN and CSS on MDN.

Associated file extensions

.css, .less

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: text/css

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="text/css">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');    
    
    http.createServer((req, res) => {    
      res.setHeader('Content-Type', 'text/css');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.css, .less

FAQs

Why do I see the error 'Resource interpreted as Stylesheet but transferred with MIME type text/html'?

This error usually occurs when the browser requests a CSS file but the server returns an HTML page instead, often a 404 Not Found error page. Verify that the file path in your HTML <link> tag is correct. If the file exists, check your server configuration to ensure it is sending the correct text/css header rather than a default text/html.

How do I configure my web server to serve CSS files correctly?

Most servers are pre-configured, but you can manually set this mapping. For Apache, ensure your configuration or .htaccess includes AddType text/css .css. For Nginx, verify that the mime.types file is included in your nginx.conf and maps .css to text/css.

Is the type="text/css" attribute required in HTML5?

No, in HTML5 the type attribute is optional for <link> and <style> tags. Browsers assume text/css by default when rel="stylesheet" is used. However, the web server must still deliver the file with the Content-Type: text/css HTTP header for the styles to be applied correctly.

Can I use text/css for LESS or SASS files?

No, browsers cannot natively interpret preprocessor files like LESS or SASS if served directly. These files must be compiled (transpiled) into standard .css files before being served to the client as text/css. Serving raw LESS code as text/css will result in syntax errors in the browser console.

What happens if the MIME type is set to text/plain instead of text/css?

Modern browsers perform 'Strict MIME Type Checking' for security reasons. If a stylesheet is served as text/plain and the server sends the X-Content-Type-Options: nosniff header, the browser will refuse to load the styles. Always ensure the correct text/css type is used to prevent rendering issues.

Are there other valid MIME types for CSS?

text/css is the only standard and valid MIME type for Cascading Style Sheets defined by IANA. Historical or non-standard types like application/x-css or text/x-css are obsolete and should not be used in modern web development.

General FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.