luci-theme-bootstrap: use system font stack with CSS custom properties

[314systems]

• This PR is not from my main or master branch 💩, but a separate branch ✅
• Each commit has a valid ✒️ Signed-off-by: <[email protected]> row (via git commit --signoff)
• Each commit and PR title has a valid 📝 <package name>: title first line subject for packages
• Incremented 🆙 any PKG_VERSION in the Makefile
• Tested on: (architecture, openwrt version, browser) ✅
• ( Preferred ) Mention: @ the original code author for feedback
• ( Preferred ) Screenshot or mp4 of changes:
• ( Optional ) Closes: e.g. openwrt/luci#issue-number
• ( Optional ) Depends on: e.g. openwrt/packages#pr-number in sister repo
• Description: Replace hardcoded font-family declarations with CSS custom properties (--font-sans, --font-serif, --font-mono) that utilize system UI fonts.

[systemcrash]

Can you further detail advantages, how this might improve upon what we have today?

[feckert]

@314systems The source code should be fine.
But you are now changing the current fonts.
Could you please describe in more detail why this is necessary as requested by @systemcrash

[314systems]

@systemcrash
This update replaces hard‑coded font declarations with CSS variables that point to each platform’s system font stack. This centralises the font settings and ensures appropriate fonts are chosen for both Latin and non‑Latin scripts across different operating systems.

[feckert]

I fin with that. But my point is that you change the current font.

[feckert]

You are changing the current font:
--font-sans: ui-sans-serif, system-ui, sans-serif;

[314systems]

This uses the native system UI fonts, avoids legacy Helvetica/Arial overrides, and is more in line with modern web typography practices.

[feckert]

And this is not used?

[systemcrash]

Closed by 3c3a5e2