On mobile: move search bar to the bottom

Hello there,

On mobile, the "Search everywhere..." search bar is located at the top, which is nice, but is a bit far for most people's fingers.

Today, mobile browsers even have the url bar at the bottom for reachability purposes.

Would it be possible to have the search bar be sticky at the bottom on the viewport instead of at the top?

Basically having `bottom: 0` instead of `top: 0` for `header` and setting `top: 0` instead of `top: 60px` for `main` in the css.

WDYT?

Start by locating the CSS rules for the header and main elements mentioned in the issue, then inspect their mobile layout in a browser. The search bar should remain sticky at the bottom of the mobile viewport, with the main content starting at the top without the current offset; verify the result at mobile widths.

Written by the indexing model from the issue text.