Site updates - refactor Header.tsx

[thetarnav]

Took some time to rewrite the logic of the Header component to remove the amount of state synchronization in effects and instead derive as much state as possible.
It works fine on chrome / ff on windows, but I have no idea if I didn't break something on safari.
Not sure about keeping styles in the styles store. there might be a better solution.
the styles are now fully derived as well.
I would some help in making sure everything works on Safari

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