Added color contrast to the active option in dropdown menu of navbar

[sahitya-chandra]

Description

Added a background-color #ffffff26 to show the active option inside the dropdown menu of navbar separately.
Fixed the grey color of main text of that active option for better visibility.

Related issue

fixed #899

How Has This Been Tested?

I have tested the changes locally.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[sahitya-chandra]

@dpgiakatos Sir Please review this code.

[dpgiakatos]

Thanks