Closes#328
## Changes
The app has favicons now!
Added:
- SVG
- Changes to slightly brighter colours in dark mode for better contrast!
- Fallback ICO
- `apple-touch-icon` (some browsers also use this, not just iOS)
- Web manifest with app description
- Two web manifest icon sizes should users add the app to their local
launcher (Windows' Start or macOS' Dock / Launchpad
- Lighting & render by @emma-sg, thanks!
The manifest and icons are copied to the root directory at build time by
webpack. All of the dedicated ways of doing this seemed more complicated
than this?
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Co-authored-by: emma <hi@emma.cafe>
