checkbox.css icons are incorrect with Live Preview (v0.13.4)

[paulsp]

The icons display by Live Preview (v0.13.4) do not match the ones displayed in preview mode.

[Connor-yang96]

https://forum.obsidian.md/t/5-checkbox/35758

[OliverBalfour]

I updated this snippet to work really well in Live Preview by combining this snippet with the one @Connor-yang96 posted:

https://gist.github.com/OliverBalfour/b87459fd55cf1f5832a2e0996a6f45a0

There's also a more complicated snippet here: https://github.com/SlRvb/Obsidian--ITS-Theme/blob/main/Guide/Alternate-Checkboxes.md

@deathau may be worth merging my snippet into your repo? It's basically the same except with live preview support. You're welcome to do whatever you like with it :)