[Masks] CSS issues with custom sheet

I'm trying to create a custom character sheet working off the Masks sheets located on the GitHub. I selected Custom for the Character Sheet Template and copy-pasted the HTML, CSS, and translation files over without making any changes.

For some reason, there were immediately a number of issues with recognizing the CSS. I was able to fix a few of them by tweaking things like selectors in the stylesheet but am still running into problems. If I check the source code from within the game, it seems like some of the CSS is just not being recognized and applied, but I'm not sure why because it looks fine to me and I haven't done anything except copy-paste it from GitHub. 

As an example, the roll template CSS is not showing up at all, but the functionality is fine. There are also some checkboxes that are supposed to hide certain divs (specified in the CSS) which aren't working.

Does anyone have ideas about why this would happen and how I can fix the problem?  

Seems to work for me. Here's some things to check.

1. The masks sheet is a legacy sheet. Make sure you have legacy sanitization enabled for your custom sheet
2. The labels rolls don't seem to work unless you've entered a value in the associated input.

It's common  mistake nr.3 : https://wiki.roll20.net/Sheet_Mistakes#3

The checklist is always good to go through when editing roll20 sheets.