mCSS 1.0.0

The official launch. Everything from the 0.9 beta reviewed, restructured, and built out into a full component framework for websites. Read the announcement post, or jump straight to the docs.

mCSS follows the copy-it-you-own-it model: there is no package to install or update. Grab dist/mcss.css (or mcss.min.css), copy the pieces you want, and edit them like anything else you wrote.

Highlights

• Component library: 26 documented components, from atoms (button, badge, toggle) through content patterns (card, hero, FAQ, testimonial, pricing, pagination) to full page chrome (header with mobile menu, footer, banner). Plain HTML + CSS first, with optional Astro components. Every one is dogfooded on mcss.dev.
• Theme system: a theme is one CSS file that reskins your whole site. Themes get their own cascade layer, above the framework and below your own CSS. theme.default.css is a copyable starting point, and theme.wireframe.css (a hand-drawn wireframe skin) is the worked example. See the themes docs.
• Native cascade layers: settings, base, elements, global, components, theme, helpers. Layer order, not import order or specificity, decides priority, and your own unlayered CSS beats the framework by default.
• Layout library: six page-level scaffolds (.layout, .layout-centered, .layout-sidebar, .layout-docs, .layout-split, .layout-cover) with full-page demos and thumbnail diagrams in the layouts docs.
• Marketing template: a complete one-pager built only from the framework and library components, with a runtime theme switcher. Live demo.
• dist/ build: the whole framework pre-processed as a drop-in file, plus per-file copies in dist/css/, committed and kept fresh by CI.
• Docs for AI agents: /llms.txt, /llms-full.txt, and a markdown twin of every docs page. See the AI docs.
• MIT license.

Breaking changes since 0.9

• Helper class short forms removed; use the full names.
• Component extraClass props renamed to class.
• The atoms layer collapsed into components; atom.* files are gone.
• The 0.9 global.layout.css internals replaced by the layout scaffolds above.
• The unused pages layer removed from the layer order.
• settings.theme.default.css renamed to settings.ui.css; "theme tokens" are now "interface tokens", and themes live in theme.*.css files.
• --theme-border-color and --theme-shadow-color renamed to --ui-border-color and --ui-shadow-color.
• Docs URLs lowercased on mcss.dev.

The full list of changes is in the changelog. The last pre-1.0 state of the old file tree is preserved under the v0.9.0 tag.

If you build something with mCSS, come show it off in the discussions.