[FEATURE] Switch theme depending on browser configuration without JS

[Ppjet6]

I have checked all the prerequisites below and I don't see this is available

• Read the README.md
• Have the extended version of Hugo installed
• Used the exampleSite's config.toml as a reference

Describe the feature

My website has the light theme enabled by default but I use the dark theme. When disabling JS for unrelated testing, I realized I don't have access to the dark theme anymore.

My browser is configured to prefer dark themes and I know this preference is used in other websites.
This would allow degrading (no JS) to still permit theme switching.

Desktop (please complete the following information):

• OS: Linux
• Browser: Firefox nightly 111.0a1

[onweru]

@Ppjet6,

I have explored this one. While I have applied simple fix for this, it will not help beyond the theme switching.

If javascript is disabled at the browser level, at least these other functions won't work 👇🏼

1. Mobile menu
2. Docs sidebar
3. Color mode switching
4. Search
5. Buttons' spacing.

Of these, only #1 & #5 I could see myself considering supporting where javascript is disabled in future.