Add dark/light mode toggle for the documentation site

[MOHITKOURAV01]

The documentation site for Helmet.js (https://helmetjs.github.io/) currently uses a bright light theme only.
For users who prefer or work at night, or in low-light environments, a dark theme or a light/dark toggle would greatly improve readability and reduce eye strain.

Proposed Solution

• Add support for dark mode (or a toggle between light and dark themes).
• Use prefers-color-scheme media query to detect system preference by default.
• Provide a toggle UI element (e.g., a switch / icon) on the site header/footer so users can manually switch.
• Ensure documentation text, code blocks, backgrounds, links maintain contrast in both modes.
• Optional: Save user preference in localStorage so site remembers their choice.

Why This Helps

• Many developers use dark mode in their editors & system; having docs in dark mode aligns with their workflow.
• Improves accessibility for users sensitive to bright backgrounds.
• Enhances overall UX and shows attention to detail in the project.

Additional Info

• Browser: Tested in Chrome/Firefox on Windows/macOS.
• Site build: Uses static docs (check repo for details).
• Happy to propose a PR (CSS + minimal JS) if this enhancement is accepted.

Checklist

• [ ✅ ] I have read the Code of Conduct
• [ ✅ ] I have reviewed the Contributing Guide
• [ ✅ ] No existing issue requests this same feature (searched issues)

[EvanHahn]

I believe this is already done. Are you seeing different behavior?

[MOHITKOURAV01]

@EvanHahn You’re right, the site already follows the system theme automatically.
I just wanted to suggest adding a small toggle button so users can manually switch between light and dark mode without changing their device settings.
It would make the docs a bit more user-friendly and flexible. Would you consider adding this feature?

[EvanHahn]

Right now, I'm not planning to add a light-dark mode toggle unless more people express interest. I'll leave the issue open to see if others chime in—if there's enough demand, I'll reconsider. Thanks!

[MOHITKOURAV01]

Totally understand, thanks for clarifying I appreciate you keeping the issue open — I’ll keep an eye on it in case others show interest.It’s a small UX detail, but I think users would really enjoy the manual toggle option. Thanks again for considering