Fix: theme reset button visibility logic

[Duckaet]

Problem

The theme reset button currently shows whenever any theme override is active, even when clicking it would produce no visible change.
For example:

• System preference: Light theme
• Website override: Light theme
• Reset button: Shows but clicking does nothing (already matches system)

This creates a confusing user experience where the button appears functional but provides no feedback.

Solution

• ✅ Show reset button when override differs from system preference
• ❌ Hide reset button when override matches system preference or no override exists

i removed the visiblity rules from scss file and used clear_theme_visiblity() function to implement the visblity logic

Before/After Behavior

System Theme	Website Override	Before	After	Result
Light	Dark	Shows	✅ Shows	Clear visual feedback
Dark	Light	Shows	✅ Shows	Clear visual feedback
Light	Light	Shows	❌ Hidden	No confusing "broken" button
Dark	Dark	Shows	❌ Hidden	No confusing "broken" button
Any	None	Hidden	❌ Hidden	Consistent behavior

[bjorn3]

Shouldn't the reset button be shown whenever localStorage.getItem("theme") is defined? Even if the currently set theme matches the system color scheme, you should probably still be able to clear the theme such that when you change the system color scheme this website follows rather than keeps the stored color theme.

Edit: That is actually what you are trying to avoid according to the PR description. I personally don't agree that the button should be hidden in this case, but phil-opp will have to decide which of the two behaviors they prefer.

[Duckaet]

yep it totally depends on him, the button feels broken from my perspective