1. I've been searching all over the internet and I still do not know if it's possible to add a button to decrease/increase the font size? Like from 12 to 16 px?
2. Speaking of fonts, can 2 or more be imported in Twine 1.4 + give the user the option to choose which one to use at the start of the story?
3. I'm really interested in adding music to my project, but not without a mute or control volume button. Can it be done?
I hope this could help you.
You'll need an exit macro to put a </div> at the bottom of the page.
Might be able to do it with Sugarcubes PassageHeader and PassageFooter passages. You may find that you'll need to redefine how things like headers work if you want them to work right (may be easier to do with a widget that'll build a <div style=""> rather than by messing with the header tags themselves).
Buttons can be done quite simply with sugarcubes <<click>> macros.