Redesign header

[KTibow]

Of course redesigning anything is a big change, so let me justify this:

• The current header has a lot of dead code (eg styling for the nonexistent discord-button and banner-video) and out of scope code (eg styling for body that should go with the rest of the styles).
• The current header takes up a lot of space (192px to be exact, the same as 7.5 lines of text).
• The current header has some small touch targets (eg dead space between links instead of clickable area).

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The new header is more compact, inspired by the headers VitePress uses:


Since the new header is compact, it can afford to stick at the top, so I've done that. This removes the need to scroll up to the top every time you need to use the nav.

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Despite being more compact, it has larger touch targets than the old one:

vs

Having larger touch targets is helpful to both mobile users (who see everything smaller due to the current lack of meta name="viewport" tags) and desktop users (who still have a cursor to maneuver).