Senior-level UX and design-system knowledge, packaged so your AI agent applies it automatically.
Skill Claude CodeCodex
UI design and review should apply Nielsen's 10 Usability Heuristics — the foundational principles for evaluating and improving usability. Use when auditing an interface, designing interaction flows, writing error messages, or reviewing any UI for usability issues.
Skill Claude CodeCodex
When something goes wrong, the user must be able to recover or try again. Toasts, inline errors, banners, and notification patterns each have a specific role. Use when designing error states, success confirmations, async feedback, in-place editing, or any system that communicates state changes to the user.
Skill Claude CodeCodex
Operational expert tools — used by domain specialists for hours every day — require a different design approach than consumer or occasional-use software. Information density, workflow linearity, and at-a-glance status take priority over whitespace and discoverability. Use when designing dispatch tools, warehouse…
Skill Claude CodeCodex
Audit UI performance with Lighthouse and fix Core Web Vitals — LCP, CLS, INP. Fast UI is good UX. Use when optimising page load, fixing layout shift, reducing input delay, improving Lighthouse scores, or reviewing images, fonts, and render-blocking resources.
Skill Claude CodeCodex
UI patterns borrowed from the physical world feel immediately intuitive — cards feel graspable, carousels feel scrollable, drawers feel pullable. Use real-world metaphors deliberately to reduce the learning curve and make interactions feel natural. Use when designing layout patterns, gestures, or navigation paradigms.
Skill Claude CodeCodex
Any component rendered many times — cards, list rows, table cells, nav items, tiles, KPI widgets, feed entries — is a fixed slot model, not a free-form box. The same slots appear in the same place in every instance and stay aligned across siblings even when text and values vary in length. Reserve space for optional…
Skill Claude CodeCodex
Mobile, tablet, and desktop are different interaction paradigms — not the same layout scaled up or down. Sections can be hidden, repositioned, or made sticky on mobile. Navigation and primary actions move. Use when designing responsive layouts, adapting desktop UI for mobile, or deciding what to show on each…
Skill Claude CodeCodex
Scroll areas inside a layout should be avoided wherever possible. When unavoidable, allow only one scroll axis at a time and always keep the user in control. Use when designing layouts, data tables, panels, or any component that might introduce an inner scroll container.
Skill Claude CodeCodex
Semantic HTML5, SEO fundamentals, alt texts, progressive enhancement, SPA considerations, device capability detection, and user context awareness. Good HTML is the foundation of accessibility, SEO, and resilient UI. Use when building any web UI, reviewing markup quality, or optimising for search and accessibility.
Skill Claude CodeCodex
Keep status and error colours minimal and consistent — too many semantic colours confuse users. Each colour must mean exactly one thing. Errors should be recoverable, large failures must be prevented, and the UI should always give the user a path forward. Use when designing status indicators, error states, form…
Skill Claude CodeCodex
Sticky and fixed positioning keeps critical UI persistent as the user scrolls — headers at the top, toolbars at the bottom on mobile. Use deliberately: too many fixed layers create visual noise and reduce content area. Use when designing navigation headers, bottom toolbars, floating action buttons, or table column…
Skill Claude CodeCodex
Tabs organise related content under a shared context — switching tabs swaps the view without leaving the page. Use when a screen has multiple distinct content areas that share a common header or action set, and when the user needs to switch between them frequently. Use when designing tabbed layouts, content panels…
Skill Claude CodeCodex
UI should make it immediately clear where the user is, what context they are operating in, and what their actions will affect. Use lines, regions, colour areas, breadcrumbs, and scope labels to communicate hierarchy and context — especially in deep navigation structures or multi-section layouts.
Skill Claude CodeCodex
UI density — how much information and how many features appear at once — should match the primary platform and user type. Desktop supports dense, feature-rich interfaces; mobile requires focused, reduced layouts. Enterprise power users tolerate higher density than occasional users. Use when designing data tables…
Skill Claude CodeCodex
Related features and tasks — such as purchase flows, onboarding, or multi-step configuration — should be designed as natural, guided paths that feel coherent and fit the product hierarchy. Use wizards for complex sequential tasks. Use when designing flows, onboarding, checkout, setup sequences, or any multi-step user…
Skill Claude CodeCodex
The most important actions and content in a UI should be visually prominent — through size, colour, weight, and position. Visual hierarchy guides the user's eye to what matters most and signals which action is primary. Use when designing button groups, CTAs, dashboards, cards, or any layout where actions or content…
Skill Claude CodeCodex needs its repo
UI must comply with WCAG 2.2 Level AA, as required by the European Accessibility Act (EN 301 549). Do not deviate without deliberate justification. Disabled UI elements are explicitly exempt from colour contrast requirements. Use when designing, building, or reviewing any user-facing interface for accessibility…
Skill Claude CodeCodex
Which CSS unit a value should be written in. rem for anything a text-size preference must move — type, control heights, padding around text. px only for what must not move — hairlines, borders, shadow offsets. Relative units for layout widths. Use when defining spacing and sizing tokens, choosing between px and rem…
Skill Claude CodeCodex
Rebuild an existing web page 1:1 from measurement instead of by eye — into Figma, Penpot, or code. Captures the rendered page, the raw source and the computed styles, rebuilds section by section, then verifies the result visually, structurally and semantically. Use when reproducing a live page as editable layers or…
At most 3 mods per repository are shown here, and a mod shipped inside a plugin is left to that plugin's page — the rest are on their repository pages: