Open CSS files in your browser
The styles of every web page: its colors, fonts, layouts and animations. Open a stylesheet right here to see its palette, its breakpoints and every rule. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your stylesheet opens summed up, its colors as a palette above its fonts, breakpoints and custom properties.
- Every color, font and breakpoint • How often each is used
- Every rule in a tree • A swatch for each color
- Minified files shown formatted
- Export • Save formatted or minified
About CSS
Håkon Wium Lie proposed CSS in 1994, and the W3C published it with Bert Bos in 1996. A stylesheet is a list of rules: a selector, like .button or nav a:hover, then declarations, like color: #3B82F6, for the elements it picks. At-rules group rules, such as @media for screen sizes, @supports for what a browser can do and @layer for which rules win, and rules can nest inside rules.
Custom properties, like --brand: #3B82F6, name a value once for var(--brand) to use it anywhere, and @font-face names the font files a page draws its text with. Sites send their CSS minified, every space and line break cut, so a whole stylesheet is one line no one can read.
Filepeek reads the file with its own CSS reader and sums it up in Overview: every color with how often it's used, however it's written, the fonts and the files @font-face names, the breakpoints with their widths, each custom property with its uses, the animations and every !important. Tree shows the rules inside their at-rules, with colored values and a swatch for each color, Text shows a minified file formatted, and Export saves it formatted or minified. Nothing in the file ever styles the page.
Cascading Style Sheets
.css
Format
- MIME type
- text/css
- Made by
- Håkon Wium Lie and Bert Bos, at the W3C
- Released
- 1996
Inside the file
- Rules
- Selectors and declarations
- At-rules
- @media, @supports, @layer and @font-face
- Values
- Colors, lengths, fonts and custom properties
- Encoding
- UTF-8 or one it names
Opens in every browser
Browsers show a CSS file as plain text, and a minified one as one long line. Filepeek sums it up and shows every rule in Chrome, Edge, Firefox and Safari.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Questions
How do I open a CSS file?
Drop it on this page or choose Peek a CSS. It opens at once with its colors, fonts and breakpoints summed up, and every rule a click away in Tree.
Can I read a minified CSS file?
Yes. Text shows it formatted, each rule and declaration on a line of its own, and Export saves it formatted or minified.
Which colors does a stylesheet use?
Overview shows every color with how often it's used, with #FFF, #FFFFFF, white and rgb(255 255 255) counted as one. Click a color to copy it.
Does the file change how the page looks?
No. Nothing in it styles Filepeek's page, and nothing it points to, like fonts or pictures, is loaded.
Is my file uploaded?
No. The file opens inside your browser and never leaves your device.