Creating social media dashboard using Grid and Js

As @besttlookk mentioned, The white space at the bottom of the screen is because of the content of the page (height required) is less than the screen's height or viewport's height.

We can resolve this issue by adding a min-height: 100vh; to the <section class="section"> tag and overall your design and transition between theme looks good!

Only issue i found is , when in dark mode..there is some area of white at the botttom (for larger screen.

Apart from that everything looks great.