fix(web): match highest accuracy card to neighboring blocks

[dibenkobit]

What changed

Use the same background and border as the neighboring blocks for the highest-accuracy card (black in dark mode, white in light mode). Keep the small green label accent.

Why

The large green fill looked muddy in dark mode and dominated the card.

Verification

• Passed pnpm format:check, pnpm lint, pnpm --filter @llang-gap/web typecheck, and pnpm --filter @llang-gap/web build.
• Checked EN language detail in dark and light themes at desktop and mobile widths; captured matching before/after screenshots. After screenshots use the production build.
• Cosmetic CSS change; no new unit tests or documentation needed.

UI changes

Dark theme

Light theme

Checklist

• This PR addresses one concern, and I reviewed the diff.
• I explained the problem, the change, and the verification results.
• I updated affected documentation and regression coverage, where applicable.
• I attached UI evidence and checked the required language(s), where applicable.

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Project	Deployment	Actions	Updated
langgap-web	Ready	Preview	Sep 9, 2026 8:57am UTC