UX Conventions

Apply when building or modifying user-facing UI components.

Brand & Visual Identity

Keywords: crystal-clear, subtle, detail-oriented, high-precision. Visual inspiration: glass-like surfaces. Clean, translucent, precise.

Default palette: clean neutral grays on white. Accent palettes (Nord, Flexoki) available as user preferences; brand stays monochrome with the Stella § mark.

Brand colours (reference, not for hard-coding):

Use semantic tokens (bg-muted, text-foreground, border) rather than raw colour values.

Colour Discipline

• One accent per surface. A screen region gets at most one saturated accent; everything else is neutral or semantic status colours. Competing accents create visual noise.
• No pure #000000 backgrounds in the app chrome. Use the --background token (neutral-950 blend in dark mode) so surfaces retain subtle warmth and depth.
• Saturation ceiling: accents should stay under 80% saturation in oklch. Neon, oversaturated gradients, and glowing outer shadows are off-limits; they read as consumer/gaming, not professional.

Core Beliefs

• Users notice the little things
• Every interaction should feel smooth
• Good UX is invisible; it just works
• Minimum clutter; keep users in the flow

Micro-interactions

Small, almost invisible touches. Linear is a good reference.

• Number/count transitions: subtle fade (~200ms). No flashy slot-machine animations.
• State transitions (loading, success, error) should feel continuous, not jarring.
• When in doubt, simpler is better, or skip it.

Icon Semantics

• Use the magic wand icon for AI text rewrite/refine/redraft actions, including search query refinement and prompt editing. Do not use generic sparkles for this function.

Reduce Visual Noise

• Secondary information (counts, metadata) subtle by default. Use opacity transitions to reveal details on hover.
• Don't compete for attention; let the content speak.

Typography Polish

• -webkit-font-smoothing: antialiased on macOS for crisper text on light backgrounds. Apply globally in the base stylesheet.
• font-variant-numeric: tabular-nums on any element whose number changes dynamically (counters, timers, tables with numeric columns). Prevents layout shift.
• text-wrap: balance on headings and short text blocks to distribute lines evenly. text-wrap: pretty on body/paragraph text to avoid orphans.

Surfaces & Depth

• Concentric border radius: when nesting rounded elements, outer radius = inner radius + padding between them. Hard-coding both to the same value produces a visual mismatch.
• Shadows over borders: prefer layered semi-transparent box-shadow for depth and separation. Reserve border for semantic boundaries (inputs, dividers), not for creating depth.
• Image outlines: for images on white/light backgrounds, add a subtle outline: 1px solid rgb(0 0 0 / 0.06) to define the edge without a heavy border.

Interactions & Animations

• Never use transition: all. Always specify exact properties (e.g., transition: opacity 150ms, transform 150ms). all triggers unnecessary repaints and can animate properties you didn't intend.
• GPU-friendly properties only. Animate transform and opacity exclusively. Never animate width, height, top, left, padding, or margin; these trigger layout recalc. Use scale/translate instead.
• Interruptible animations: use CSS transition for interactive state changes (hover, press) so the browser can interrupt mid-animation. Reserve @keyframes for staged sequences (page load, modals).
• Staggered list entry: when a list or grid appears (page load, filter change), cascade items with a small stagger delay (30–60ms per item, capped at ~8 items) so the group reads as a cohesive reveal rather than a sudden block.
• Optical alignment over geometric: icons inside circles, play-button triangles, and asymmetric glyphs should be nudged visually until they look centred, even if that means offset from the geometric centre.

Empty States & Inline Help

• An empty state earns one line, and that line is an action (the gesture that fills it), not a definition. Teach "Select text → right-click → Make field", not what a field is. Conceptual education lives in tooltips or docs, never as permanent panel prose.
• Full-width buttons are reserved for a surface's single primary action. Structural or secondary adds use quiet ghost affordances (small +, text button).
• Side-panel sections with zero items collapse to a single row (heading + count + add affordance) by default; they expand on demand or when they gain content.

Loading States

• Skeleton loaders must match the real layout. The skeleton's dimensions, spacing, and column count should mirror the content it replaces so the page doesn't shift on load.
• Inline spinners over full-page loaders. Scope loading indicators to the region that's actually waiting. A full-page spinner for a sidebar fetch is disorienting.
• Render the destination's structure, not a logo. When a route loads, show its real shape (table chrome with header and columns, toolbar, section cards) with the values shimmering in. The centered glowing logo (DefaultPendingComponent) is the last-resort fallback, not the default. Give each route its own pendingComponent so the route you navigate to picks its own shape.
• Skeletons must be structurally drift-proof. Generate the skeleton from the same source as the real UI, never a hand-copied parallel tree. For tables, render the header, rows, and skeleton from one column model (@stll/ui table plus the shared TableSkeletonRows helper) so adding or reordering a column moves all three at once. Where the page chrome does not need the data, move the Suspense boundary inward (render the real chrome, suspend only the leaves). For scaffolds that cannot share a source, mirror the real layout faithfully.

Viewport & Responsive

• Use min-h-dvh, not h-screen. h-screen ignores the mobile browser chrome and causes scroll/overlap bugs. dvh units adapt to the dynamic viewport.

Hit Areas

• Stella targets a minimum 44×44 CSS-pixel touch area for interactive controls. If the visible element is smaller, extend its hit area without changing the visual size or colliding with adjacent controls.
• Use native interactive elements and preserve keyboard activation, focus order, accessible names, and visible focus. A clickable div with ARIA is not a substitute for a button or link.
• Respect reduced-motion preferences. Meaning and completion feedback must not depend on animation, hover, colour alone, or pointer precision.

Right-to-Left (RTL) & Bidirectional

Stella ships an Arabic (RTL) UI; every surface must mirror correctly and stay locale-aware. Test new UI in ar (not just en) before shipping — flipping documentElement.dir is not enough on its own.

• Logical properties only. Use ps-/pe-, ms-/me-, start-/end-, border-s/-e, text-start/-end — never physical pl-/pr-, ml-/mr-, left-/right-, text-left/right, border-l/-r, rounded-l/-r. Physical directional classes do not flip under dir="rtl". Enforced by the no-physical-properties oxlint rule.
• Mirror direction, not identity. Render directional glyphs (chevrons, arrows, back/forward, next/prev, breadcrumb separators, pagination, drawer toggles) through <DirectionalIcon icon={...} /> (@stll/ui), which centralizes the rtl:-scale-x-100 mirror. Do NOT mirror brand marks/logos, the media play triangle, checkmarks, or anything whose meaning is orientation-free. For disclosure chevrons that rotate-90 on expand, pass flip={!isExpanded} so the mirror applies only while collapsed — an always-on mirror composes with the rotation and points the expanded state the wrong way.
• Format through the central locale. Route all numbers, dates, and relative times through useFormatter()/getFormatter() (or pass getFormattingLocale()); never a bare Intl.* / .toLocale*String() with the base lang or no locale — that drops the user's numbering-system preference (e.g. Eastern Arabic-Indic digits). Enforced by the no-raw-locale-format oxlint rule.
• Isolate embedded Latin & numerals. Wrap Latin runs inside RTL text (case numbers, ECLI, citations, file names, emails) in <bdi> so bidi reordering doesn't scramble neighbouring punctuation. Use dir="auto" on free-text user inputs; keep tel/email/url and code fields LTR.
• Panels mirror as a unit. A panel on the inline-end in LTR (right) docks to the inline-start in RTL (left); its internal rail + content keep their relative order automatically via flex + logical props — never pin with physical right-0/left-0.
• Document surfaces stay LTR-based. The editor/document canvas (folio) keeps an LTR base direction even under an RTL UI; only the app chrome mirrors. Brand wordmark/logo is never mirrored or transliterated.
• No untranslated LTR islands. Don't leave English strings (suggested prompts, labels, empty-state copy) inside an otherwise-Arabic surface; route them through i18n. A Latin island reads as "unfinished," not "global."

Anti-Patterns

Explicit list of patterns that AI agents tend to generate and that do not belong in a professional legal workspace:

• No emojis in the product UI. Use Lucide icons or semantic status colours instead.
• No "AI aesthetic" chrome: purple/blue neon glows, pulsing gradient borders, holographic effects. Stella's AI features should feel like native tools, not a tech demo.
• No centred hero sections in application views. Heroes belong on marketing pages; app screens use content-first layouts.
• No generic three-equal-cards grids. If content genuinely comes in threes, fine; but don't default to grid-cols-3 as the go-to layout. Prefer asymmetric grids, two-column splits, or list views that match the data shape.
• No filler copy. Never use "Lorem ipsum", "John Doe", "Acme Corp", "99.99%", or similar placeholder text in committed UI. Use realistic legal-domain examples (matter names, party names, deadlines) or leave the slot empty with a proper empty state.
• No AI copywriting clichés: "Elevate", "Seamless", "Unleash", "Revolutionize", "Supercharge". Write plain, specific microcopy.
• No decorative scroll indicators (bouncing chevrons, "Scroll to explore" text). If content scrolls, the scrollbar is sufficient affordance.
• No custom cursors or pointer overrides beyond the standard pointer for interactive elements.