Fix country flag emojis not rendering on Microsoft Edge/Windows

[Copilot]

Windows omits flag emoji glyphs from its system emoji font, and Chromium-based browsers (Edge, Chrome) don't bundle their own — causing all flag emojis to render as two-letter country codes (e.g. US) instead of 🇺🇸.

Changes

• country-flag-emoji-polyfill — added as a dependency; uses canvas-based detection to determine if flag emojis are unsupported, then injects a @font-face rule for the Twemoji Country Flags font only when needed (no-op on Mac/Linux/Firefox)
• public/fonts/TwemojiCountryFlags.woff2 — font copied from the npm package for self-hosting; avoids CDN dependency
• providers.tsx — calls polyfillCountryFlagEmojis() on mount with the self-hosted font path:

  React.useEffect(() => {
    polyfillCountryFlagEmojis('Twemoji Country Flags', '/fonts/TwemojiCountryFlags.woff2');
  }, []);

• Theme.ts — prepends "Twemoji Country Flags" to the MUI fontFamily. The font's unicode-range: U+1F1E6-1F1FF scopes it exclusively to regional indicator code points, leaving all other text rendering unaffected

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• download.cypress.io
  • Triggering command: /opt/hostedtoolcache/node/24.14.0/x64/bin/node /opt/hostedtoolcache/node/24.14.0/x64/bin/node index.js --exec install (dns block)
  • Triggering command: /opt/hostedtoolcache/node/24.14.0/x64/bin/node /opt/hostedtoolcache/node/24.14.0/x64/bin/node dist/index.js --exec install (dns block)
• www.npmjs.com
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

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Project	Deployment	Actions	Updated (UTC)
mobilitydatabase-web	Ready	Preview, Comment	Mar 5, 2026 1:11am

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[github-actions]

*Lighthouse ran on https://mobilitydatabase-if4hypr4b-mobility-data.vercel.app/ * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🟢 93	🟢 96	🟢 100	🟢 100

*Lighthouse ran on https://mobilitydatabase-if4hypr4b-mobility-data.vercel.app/feeds * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🟠 89	🟠 87	🟢 96	🟢 100

*Lighthouse ran on https://mobilitydatabase-if4hypr4b-mobility-data.vercel.app/feeds/gtfs/mdb-2126 * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🔴 31	🟢 94	🟢 96	🟢 100

*Lighthouse ran on https://mobilitydatabase-if4hypr4b-mobility-data.vercel.app/feeds/gtfs_rt/mdb-2585 * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🟢 99	🟠 83	🟢 100	🟢 100

*Lighthouse ran on https://mobilitydatabase-if4hypr4b-mobility-data.vercel.app/feeds/gbfs/gbfs-flamingo_porirua * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🟢 90	🟢 94	🟢 96	🟢 100