accessibility: keyboard navigation
On Nitter the currently selected element isn't highlighted on the page, making navigation without a pointer device far less viable. As an example, the 'Issues' element is active in this screenshot (from `github.com/zedeus/nitter`): 

![image](https://github.com/zedeus/nitter/assets/14923168/57a0ac5c-0c5d-49a8-ade9-c05ecbbef0d2)

Typically the Tab key (Shift + Tab moves backwards) and browser's search function (Ctrl + F) are used to navigate webpages with the keyboard.

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seemingly relevant documentation: https://developer.mozilla.org/en-US/docs/Web/Accessibility/Understanding_WCAG/Keyboard

