docs: UI improvements

[devongovett]

• Adjusts the font size of the h1 so that it fits on mobile. This is done by calculating the width of the heading at build time (relative to 1em), and then scaling the font size using that ratio.
• Makes code examples scroll horizontally instead of wrapping, which is much easier to read on mobile. The copy/open buttons are now in a floating toolbar.
• Automatically sets the type of code blocks to the correct library based on the page URL so that sandbox/zip downloads are always available.
• Adds additional aria groupings and labels so it's easier to navigate with a screen reader.

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
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• View the S2 docs

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the documentation
• View the S2 docs

[LFDanLu]

nice lol, the long headings looks good now