using sass is a spiderweb of problems

[rathboma]

fix #1874

[azmy60]

I think this is good. Some changes I made:

• I changed the way we import vendor css files a little bit, cause the old one uses ~ in the beginning of the path that doesn't work with the new config.
• For some reason, some styles we made couldn't override the vendor css after the new config. I went through some basic flows and fixed all that I've seen but obviously I wouldn't say I've covered all the breaking styles.
• I'd say most of the breaking styles would be the styles that can't override the vendor css.