add light theme

[samratghosh291]

the website is in default dark theme.
add a light theme to it.
make sure the PR has no conflict.
attach a screen shot with PR.

[Muhammad-Shahid-Jamal]

Hi, can you assign this issue to me so I can add a light theme to it via the toggle button.

[rajvinder-kaur]

i already worked on a similar feature so please assign this to me