The design language for the working day.

One stylesheet for the language and component vocabulary, one script for behaviour. Both are vanilla — no build step, no dependencies. Static markup needs only the stylesheet.

<!-- Theme (FOUC prevention) -->
<script>try{var t=localStorage.getItem("across-theme")||"system";if(t==="light"||t==="dark")document.documentElement.setAttribute("data-theme",t);}catch(x){}</script>

<!-- Across UI v2 — pin a version for cache-safety (same scheme as pkg.acrossacross.com) -->
<link rel="stylesheet" href="https://ui.acrossacross.com/v2.0.7/styles.css">

<!-- Behaviour (theme, combobox, toasts, modal…) -->
<script src="https://ui.acrossacross.com/v2.0.7/primitives.js" defer></script>
<!-- Or use /latest/ to track the newest release, /v2/ for the latest v2.x. -->

<!-- Icons -->
<link rel="stylesheet" href="https://unpkg.com/@phosphor-icons/web@2.0.3/src/light/style.css">

Everything sits on warm paper with hairline rules — no cool-gray, no shadows on chrome. Three product colors plus a chrome teal; one accent per surface.

Plus Jakarta Sans for everything human; Red Hat Mono, tabular, for every number, rate, and timestamp.

The one flourish — a sheared 2px accent edge sweeps in from the leading edge on hover, active, and press, then retreats. Interaction only, never idle. Hover any surface below.

The system is the source of truth for every Across app — the language, the components, and the prompts that let AI agents build in it.