verify-ui

name	verify-ui
description	Verify UI changes visually using browser automation before telling the user it's done. Use when making CSS, layout, or visual changes to web apps — especially Starlight docs sites, landing pages, or any frontend work. Triggers on "does this look right", "verify the UI", "check the layout", or after any CSS/HTML change.

Verify UI

After making visual changes (CSS, HTML, layout, components), always verify with a real browser screenshot before reporting success. Never tell the user "refresh and check" — check it yourself.

Why

CSS changes often fail silently:

• Scoped styles don't apply (Astro/Starlight @layer precedence)
• Class names get mangled (CSS Modules, Astro scoping)
• Flex/grid layouts break in ways that aren't obvious from code
• Elements overlap, overflow, or misalign at certain widths

The user should never be your QA. You have browser tools — use them.

Workflow

1. Make the CSS/HTML change
2. Navigate to the page in Chrome (mcp__claude-in-chrome__)
3. Take a screenshot
4. Evaluate: does it match the intent?
5. If broken → fix and re-screenshot (DO NOT tell user to check)
6. If good → zoom into the specific area that changed for confirmation
7. Only then report to the user with the screenshot as evidence

How to Use Browser Tools

First time in a session

1. ToolSearch: "select:mcp__claude-in-chrome__tabs_context_mcp"
2. Call tabs_context_mcp with createIfEmpty: true
3. ToolSearch: "select:mcp__claude-in-chrome__tabs_create_mcp"
4. Create a new tab
5. ToolSearch: "select:mcp__claude-in-chrome__navigate,mcp__claude-in-chrome__computer"
6. Navigate to the dev server URL

Taking screenshots

// Full page
mcp__claude-in-chrome__computer({ action: "screenshot", tabId })

// Zoom into a region (e.g., header area)
mcp__claude-in-chrome__computer({
  action: "zoom",
  tabId,
  region: [0, 0, 1400, 60]  // [x0, y0, x1, y1]
})

Debugging layout issues

// Read computed styles via JS
mcp__claude-in-chrome__javascript_tool({
  action: "javascript_exec",
  tabId,
  text: `
    const el = document.querySelector('.my-element');
    const cs = window.getComputedStyle(el);
    JSON.stringify({
      display: cs.display,
      flexDirection: cs.flexDirection,
      gap: cs.gap,
      width: cs.width,
    })
  `
})

Common Pitfalls

Astro/Starlight scoped styles

• Component <style> blocks are scoped with data attributes
• They often lose specificity battles with Starlight's @layer starlight.core
• Fix: use <style is:global> or !important for overrides
• Fix: use Starlight's utility classes like sl-flex instead of custom display: flex

Starlight CSS variables

• --sl-font works but Starlight wraps it in --__sl-font internally
• Override via customCss files, not inline component styles
• --sl-nav-pad-x controls header horizontal padding

Class name collisions

• Don't use .hero in a Starlight splash page — it collides with Starlight's built-in .hero
• Prefix custom classes: .landing-hero, .my-feature, etc.

Checklist Before Reporting

• Screenshot taken of the changed area
• Zoomed into specific elements that changed
• Checked mobile viewport if relevant (resize_window tool)
• Verified no overflow/cutoff at edges
• Verified text is readable and properly contrasted
• Verified alignment with surrounding elements
• If header/nav changed: checked it's on one line, properly spaced