Fix background color rendering issues for notification bell, theme toggle,
and language switcher buttons in the header bar. These buttons were missing
!important declarations in their CSS classes, causing inconsistent styling
across different devices where other styles could override the intended
background colors.
Changes:
- Add !important to background color classes for notification button
- Add !important to background color classes for theme toggle button
- Add !important to background color classes for language switcher button
- Ensure all header action buttons now have consistent styling matching
the user avatar dropdown button
This resolves visual inconsistencies where these buttons would appear
without proper background colors on certain devices or screen configurations.
