Light theme parity

[truthixify]

Tier: M (2-4 days) Type: design

Context

feature

Scope

Demo is dark-only. Many users (especially in daytime productivity contexts) prefer light. Need a tasteful light theme behind a toggle.

Acceptance criteria

• Design light theme via design tokens (CSS variables)
• Header toggle, persist preference in localStorage; default to prefers-color-scheme
• Verify contrast on every section (WCAG AA)
• Update Stellar chart syntax highlighting for light
• Animation on switch (200ms, no first-paint flash)

Files to start with

• Light theme designed + screenshots in PR
• Toggle wired + persistent
• WCAG AA in both themes
• No first-paint flash

Why this matters

• src/index.css (design tokens)
• src/components/Header.tsx