chore: adjust font stack and fix typo in css

[SethFalco]

Font Stack

Instead of using a font stack that I picked out myself, we instead use one derived from Modern Font Stacks.

I made the following changes:

• Replace Nimbus Sans with Liberation Sans, which renders more consistently between browsers.
• Omit Inter, which causes too much layout shift compared to other typefaces in the PDF export, which isn't favorable given we can't have a fluid/responsive design there.

This does incidentally make PDF exports notably smaller in some cases, for example rendering with Roboto instead of Nimbus Sans reduced the output by 30% for me.