# Scroll area > A scroll container with the same rounded scrollbar in every browser, Firefox included, and native scrolling. Surfaces · [Docs](https://ui.ssntl.app/docs/components/scroll-area) · `npx shadcn@latest add @ssntl/scroll-area` Installs `components/ui/scroll-area.tsx`, with `utils`. Read this file before you use, change or review it. ## When to use it - For a panel or list with its own scroll (a sidebar, a long menu, a code sample) where the bar must look the same in every browser. ## When not to - **For the page itself.** Let the document scroll, styled with the scrollbar utility. - Nested scroll areas in the same direction. ## Usage ```tsx import { ScrollArea } from "@/components/ui/scroll-area" ; ``` ## Rules for Scroll area - The same scrollbar everywhere, Firefox included: an 8px pill track with a 6px pill thumb nested 1px inside, so the curves are concentric. - Scrolling stays native (wheel, touch, keyboard, find in page); only the bar is drawn. - The viewport takes focus with a visible ring; give it an `aria-label` so the region has a name. - `type="hover"` shows the bar while hovering or scrolling; use "always" when people must see there is more. - Thumb on track is `--input` on `--muted`, 3:1 or more in both themes, checked in lint. ## Keyboard | Key | Action | | --------------------------- | ----------------------------- | | Tab | Focuses the scrolling region. | | ↑ / ↓ / Page Up / Page Down | Scroll it. | ## How it is built A scroll container whose scrollbar looks the same in every browser, Firefox included: a rounded 8px track with a 6px thumb nested 1px inside, so the curves are concentric. Scrolling stays native (wheel, touch, keyboard, find in page); only the bar is drawn. The viewport takes focus, so keyboard users can scroll it with the arrow keys. Names the scrolling region for keyboard and screen reader users. The 8px pill track sits 10px in from the side and 12px from the ends, so a rounded container's corner (up to radius-lg) never clips it. ## Interaction - Every control has an accessible name: its visible label, or `aria-label` for icon-only controls. - Every keyboard-reachable control shows a visible focus ring (2px, offset 2px, the ring token). - Anything you can do with a pointer you can do with the keyboard. - Targets are 48px (44px minimum for dense rows), with at least 8px between neighbours (the system's density); the hit area covers the whole visible control. - Press feedback is 0.96 scale in 150ms (`--es-press`, `--duration-fast`); never below 0.96, never slow, and a disabled control never scales. - One primary action per view; past three secondary actions, the rest go in a menu. - Hover styles only on pointer devices; never hide a control's function behind hover. - **Undo beats confirmation.** A frequent, reversible action runs at once and offers Undo (Order archived. Undo). Confirm only what can't be undone, affects other people or destroys many items. A destructive action is red text, placed last. - Never disable a submit button until the form is valid; validate on submit. While pending, use `aria-disabled="true"` with a spinner beside the label, since disabled drops focus. ## Surfaces - Static content sits at `elevation-0` and separates by tone; only what floats casts a shadow. - A shadow used as a ring keeps a 1px transparent border, so forced-colors mode still draws an edge. - Full-height areas use 100dvh, never 100vh; widths use 100%, never 100vw. Reusable components adapt with container queries (@container), not the viewport. - Content sets the height; tiles in a row stretch to the tallest. - **Nested surfaces are concentric.** Inner radius = outer radius − padding. ## Design tokens only - Use the system's tokens for every design value: type roles (`text-caption` 13, `text-label` 15, `text-body` 17, `text-lead` 20, `text-heading` 22, `text-title` 32, `text-headline` 48, `text-display` 72), radii (`rounded-xs` 8 … xl 44), spacing steps, colors, shadows and motion. If a value doesn't exist, take the nearest token. Never write text-[15px], rounded-[24px] or bg-[#…]; `pnpm lint` rejects them. - Type roles already carry line height, tracking and weight. Pick the role; never add `leading-*` or `tracking-*` on top. - **Nested corners are concentric.** Inner radius = outer radius − padding − border width (`rounded-outer`-* p-concentric-* `rounded-inner`). Past 24px of padding, or with deliberately uneven padding, each layer keeps its own radius token. - Separate surfaces by tone, not borders. A border is for structure (a divider) or state (an input, a selection). ## Accessibility baseline - Text meets 4.5:1 against its surface (3:1 at 24px and up, or 18.67px bold); input borders, focus rings and chart marks meet 3:1, in light and dark. Text on a translucent color (`white/80`, /50, color-mix) is measured as rendered over its background; the theme pairs are checked in lint. - Meaning never rides on color alone: a state carries a word, an icon or a pattern as well. - Every page fits a 320px screen at 200% zoom with no horizontal scroll; a grid that holds content uses grid-cols-[minmax(0,1fr)] and flex children get min-w-0. Never set maximum-scale=1 or user-scalable=no. - A focused element is never hidden under sticky chrome: set scroll-padding to the header's height (and to footers or banners at the bottom). - On a client-side route change, update the title and move focus to the new page's main content. - **Respect prefers-reduced-motion.** Keep opacity and color, drop movement, scale and blur. - Content is never truncated without a way to read all of it; long names wrap. A hover-only title tooltip doesn't count as a way back. ## Writing - Sentence case everywhere; no ALL CAPS except the Eyebrow role. - One concept, one word, across navigation, headings and buttons. - Buttons are a verb and its object and say what happens (Delete product, not OK). - An error says what went wrong and how to fix it, in the user's language. - **Status copy follows one pattern.** In progress is the verb in -ing (Saving changes…), done names the object and the past tense with no “successfully” (Changes saved), a failure gives the next step, partial results give counts. Cut “Please”. - A confirmation names the action and the object (Delete Ceramic cup?), never “Are you sure?”. Deleting an account, a workspace or a store asks for its name to be typed. - Show known requirements as helper text before input, not only as an error after it. Links never say “Click here”, and no two links on a page say “Learn more”. - Build each sentence as one translatable message, never concatenated around a variable; join lists with Intl.`ListFormat`. - **Use real characters.** An en dash for ranges (09:30–17:45), × for dimensions, curly quotes, an ellipsis (…). ## Fixing - Take the cheapest fix that works, in this order: delete (a separator space would carry, an animation on a frequent action, an ARIA attribute a native element makes redundant), use the platform (the native element or control, the browser's focus ring), reuse what the system has (a token, a spacing step, a motion curve), correct the value, and only then add something new. - Code that adds what a deletion would fix is a problem in itself; fix it by removing. - A documented convention settles matters of taste, but never excuses a release blocker. ## Worst-case content - Build and test with the worst real values, not the happy ones: long hyphenated names with diacritics, unbreakable emails and URLs, German compounds, translations about 30% longer, emoji and right-to-left names. - Unbreakable strings wrap anywhere; nothing pushes its siblings off a row or out of a container. - Every image has a fallback and a box: a failed avatar shows initials, a frame keeps its ratio, so loading never shifts the layout. - **Show data as data.** Escape HTML, never render null, undefined or NaN, and round floating point before display. - **Check the environment as well.** A 280px column, a 2560px screen, 200% zoom, dark mode, `dir="rtl"` and touch. ## Icons - One icon set (Lucide) at one stroke: 1.6, the Essential Design spec, beside regular and medium text; a heavier stroke only where a small glyph must read (a 16px check). (better-ui proposes rendered strokes of 1.5–2px with `absoluteStrokeWidth`; the system's documented stroke takes precedence as a matter of style.) - Inline icons are 1em–1.25em of the text beside them. - Icons are 20px beside labels and 16px in dense controls, at the size they were drawn; a well or a button, not a bigger glyph, gives them room. - One SVG per icon, colored with `currentColor`; hover, selected and disabled states come from color and opacity, never from separate assets. - Decorative icons are `aria-hidden`; an icon that is the only content of a control gets its name from the control. ## Light, dark and languages - Design both themes from the tokens; dark mode is chosen, not inverted. Check every new pair in both. - Pass every visible and accessible string as a prop or child, so the component works in any language; never hard-code copy inside it. - Use logical properties (ms-, me-, start-, end-) so layouts mirror in right-to-left languages; `translateX` and background-position need a right-to-left override. Mirror only icons whose meaning follows reading direction (arrows, chevrons), and wrap mixed-direction values in ``. - **Visual order matches DOM order.** No order, row-reverse or grid placement that reorders content. - Switching themes pauses transitions for the switch, so every surface changes at once. ## Before you ship - [ ] Every interactive control has an accessible name. - [ ] Every keyboard-reachable control shows a visible focus indicator. - [ ] Nothing is reachable by pointer but not by keyboard. - [ ] Motion and auto-playing content respect prefers-reduced-motion. - [ ] Nothing is clipped, overlapped or unreachable at 320px width or 200% zoom. - [ ] Body and control text pass their contrast ratio. - [ ] No state or meaning is carried by color alone. - [ ] Destructive actions have a confirmation, an undo, or a distinct treatment. - [ ] No content is truncated without a way to reach the full value. - [ ] No content or control hides past a scroll edge or disclosure without a visible cue. - [ ] Every error names a way to recover. - [ ] Semantic colors are used for their meaning only (danger never on a safe action). - [ ] No state change is carried by motion alone. - [ ] Nothing focused hides under sticky chrome, and overlays contain their own scroll. - [ ] Worst-case values (long, empty, many, missing, right-to-left) don't break the layout. ## Review with these skills Every interface built with ssntl/ui is reviewed with the same skills the library is. Install them once and keep them current: ```bash npx skills@latest add https://github.com/jakubkrehel/skills --skill better-interface npx skills@latest add jakubkrehel/make-interfaces-feel-better npx skills@latest add emilkowalski/skills ``` - **better-interface** (Jakub Krehel): The full review: accessibility, layout, writing, typography, color and polish. Its escalation triggers block a release. - **make-interfaces-feel-better** (Jakub Krehel): The details: concentric radii, optical alignment, press scale, interruptible and subtle motion, hit areas. - **emilkowalski/skills** (Emil Kowalski): Design engineering: easing, durations, springs and gestures (emil-design-eng, review-animations, animation-performance) and the worst-case values that break a UI (break-ui). ## Related - [Scrollbar](scrollbar.md): Rounded, concentric scrollbars from the tokens for native scroll containers, plus scrollbar-none. - [Menu](menu.md): A dropdown menu on elevation 2 whose inset header and items share the panel's curve. - [Side nav](side-nav.md): Section navigation as wide as its longest label, with aria-current for the page. --- Generated from the ssntl/ui source by `scripts/build-rules.mjs`. The whole rulebook is [ssntl-ui.md](ssntl-ui.md); every component's rules are at https://ui.ssntl.app/rules.