Frontend polish: skeleton loading states, focus-visible accessibility, gradient section dividers

[Copilot]

Chimera's loading states were plain pulsing text and there were no global focus-visible styles — keyboard/AT users had to rely on the opt-in body.keyboard-nav class. Three targeted style.css improvements address this.

Changes

• Skeleton loading states — .loading now renders as a bordered card with a sweeping shimmer gradient via ::after, using color-mix(in srgb, var(--color-accent) …, transparent) so it adapts to both themes. prefers-reduced-motion disables the animation.

  .loading::after {
    background: linear-gradient(
      90deg,
      transparent 0%,
      color-mix(in srgb, var(--color-accent) 8%, transparent) 40%,
      color-mix(in srgb, var(--color-accent-secondary) 14%, transparent) 50%,
      color-mix(in srgb, var(--color-accent) 8%, transparent) 60%,
      transparent 100%
    );
    animation: skeleton-sweep 2s ease-in-out infinite;
  }

• Global :focus-visible styles — Replaces the body.keyboard-nav-only approach with a standard :focus-visible rule: 2px accent outline + color-mix()-based glow shadow. Mouse users unaffected. Buttons/links get a larger border-radius on the ring.

• Gradient section dividers — A thin centred transparent → accent → transparent rule inserted via ::before between consecutive [id$="-section"] siblings. Adds visual rhythm without heavy weight; purely decorative.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Chimera Frontend Polish - 2026-03-01</issue_title>
<issue_description># Chimera Frontend Polish - 2026-03-01

Your Role: Frontend Design Specialist

You are a frontend polish agent with an eye for exceptional design. Your mission is to elevate Chimera's visual quality from functional to stunning. You focus purely on aesthetics, interactions, and user experience - not new features.

Design Philosophy

Create interfaces that feel intentional and crafted, not generic. Avoid the 'AI-generated' look of safe gradients and predictable layouts. Instead, aim for:

• Bold choices: Unexpected color combinations, asymmetric layouts, distinctive typography
• Subtle sophistication: Micro-interactions that feel native, shadows that add depth without being heavy
• Visual hierarchy: Guide the eye naturally, make important elements stand out
• Cohesive identity: Every element should feel like it belongs to the same design system

Areas to Polish

1. Visual Refinement

• Color palette: Refine colors for better contrast, harmony, and emotional impact
• Typography: Improve font sizes, weights, line heights, and letter spacing
• Spacing: Create consistent rhythm with margins and padding (use 4px/8px grid)
• Shadows & Depth: Add layering that feels natural, not flat or overly dramatic
• Border radius: Ensure consistency, consider more distinctive shapes

2. Micro-interactions & Animation

• Hover states: Make interactions feel responsive and satisfying
• Transitions: Smooth state changes (300ms ease-out is a good baseline)
• Loading states: Skeleton screens, shimmer effects, progress indicators
• Feedback: Visual confirmation for user actions
• Scroll animations: Subtle fade-ins, parallax, or reveal effects

3. Component Polish

• Cards: Elevation, borders, hover lift effects
• Buttons: States (default, hover, active, disabled), satisfying click feedback
• Inputs: Focus rings, validation states, placeholder styling
• Charts/Graphs: Smooth animations, better tooltips, cleaner axes

4. Layout & Composition

• Visual balance: Weight distribution across the page
• White space: Breathing room that feels intentional
• Responsive refinements: Ensure polish carries through all breakpoints
• Content alignment: Consistent grid alignment

5. Dark/Light Theme Harmony

• Ensure both themes feel equally polished (not just inverted colors)
• Proper contrast ratios for accessibility (WCAG AA minimum)
• Theme-appropriate shadows and highlights

CSS Techniques to Consider

/* Smooth, natural shadows */
box-shadow: 0 1px 2px rgba(0,0,0,0.04), 0 4px 12px rgba(0,0,0,0.08);

/* Satisfying transitions */
transition: transform 0.2s ease-out, box-shadow 0.2s ease-out;

/* Subtle hover lift */
transform: translateY(-2px);

/* Glass morphism (use sparingly) */
backdrop-filter: blur(12px);
background: rgba(255,255,255,0.7);

/* Gradient text for headings */
background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
-webkit-background-clip: text;
-webkit-text-fill-color: transparent;

/* Smooth color transitions for theme switching */
transition: background-color 0.3s ease, color 0.3s ease;

What NOT To Do

• Don't add new features or functionality
• Don't change the information architecture
• Don't use too many different colors (stick to a refined palette)
• Don't over-animate (motion should enhance, not distract)
• Don't sacrifice readability for aesthetics
• Don't ignore accessibility (contrast, focus states, reduced motion)

Process

1. Audit: Run the site (npm run dev) and take notes on what feels unpolished
2. Prioritize: Pick 2-3 high-impact improvements (don't try to fix everything)
3. Implement: Make focused, cohesive changes
4. Compare: Before/after - does it feel more premium?
5. Test: Both themes, multiple viewport sizes, interactions

Non-Negotiable Requirements

1. Build must pass: npm run build
2. Tests must pass: npm run test
3. Both themes must work: Light and dark mode equally polished
4. Responsive: Changes must work on mobile through desktop
5. Update changelog: Document your polish in BOTH README.md AND public/README.md

Changelog Entry Format

### Day [X]: 2026-03-01
**Feature/Change**: Frontend Polish - [Brief description]
**Description**: [What you improved and the visual impact]
**Files Modified**: [Usually src/style.css and possibly component files]

Verification Checklist

• npm run build passes
• npm run test passes
• Light theme looks polished
• Dark theme looks polished
• Mobile viewport looks good
• Animations are smooth (no jank)
• Accessibility not compromised (contrast, focus states)
• README.md AND public/README.md updated

Remember

You're not adding features - you're making existing fea...

• Fixes Chimera Frontend Polish - 2026-03-01 #98

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Project	Deployment	Actions	Updated (UTC)
chimera	Ready	Preview, Comment	Mar 1, 2026 1:05pm