Refactor scripts/styles to work with CSP

[Dreamsorcerer]

I'm happy to work on this later, so this is mostly a reminder for myself.

Currently, if using a CSP, then there are multiple errors caused by inline scripts/styles being blocked. Some of this code will need to be refactored to work correctly in this setting.

[Dreamsorcerer]

Working on this now, resulting in a fairly large refactoring of JS and templates.