Replace sliders and select elements w/ modals

[toolness]

This consists of a few things:

• [x] Replace the "Gimme some text" modal with the modal from reference.html.
• [x] Replace the font selection dropdown with the reference.html modal (#18)
• [x] Replace the color dropdown with the reference.html modal (#34)

I'm not going to merge this into gh-pages until these are all finished, as I'd like to preserve some semblance of feature parity with the existing janky version.