usa.gov · GovernmentHow modern is USA.gov's CSS?
Checked 2 November 2026, the CSS on its home page as any visitor gets it. Sites change, so check it now for today's numbers.
Each weekly check lands in your dashboard.
6 old techniques still there
Each with the modern way to replace it. Old CSS that works is fine; these are suggestions.
- Vendor prefixes browsers no longer needUse the unprefixed property97
- Sass color functionsUse color-mix(), relative colors1
- Font sizes set in media queriesUse clamp()366
- Negative-margin guttersUse gap330
- Floats and clearfixUse grid, flexbox, flow-root23
- 100vhUse dvh units3
Also worth a look
These don't change the score, because modern code uses them too.
- High-specificity selectorsUse @layer, :where()3,178
- ID selectorsUse classes, @layer122
- !importantUse @layer34
- Repeated selector listsUse :is()25
- html or body prefixes for weightUse @layer3
- z-index of 1000 or moreUse the top layer (dialog, popover)3
- Doubled classes for weightUse @layer1
- Physical left and rightUse logical properties2,843
- Old names for current CSSUse gap, overflow-wrap, break-before2
What USA.gov's CSS is built with
Only what the page and its CSS show, with the evidencePartFoundEvidenceHow sure
- Design systemU.S. Web Design SystemLoads USWDS stylesheets, and 393 class names start with .usa-.Very sure
- FontsRoboto Mono Web, Source Sans Pro Web, Merriweather WebLoaded with @font-face from the site's own files.Very sure
- Site frameworkDrupalIts files are served from Drupal's file paths.Very sure
- PreprocessorCan't tellSass, Less and PostCSS leave no trace in the CSS a browser gets.—
Design tokens
CSS custom properties USA.gov definesNo CSS custom properties found. Tokens a build step turns into plain values (Sass variables, most CSS-in-JS) never reach the browser, so a site can have a design system that doesn't show here.