Z-index is something that normally you don’t have to worry about it until you do.
TL;DR There is a set place for words to hyphenate and based on your set language in the HTML tag, the computer will insert hyphens where they belong.
Line height, you love it you need it. And according to WCAG 2 you need it to be 150% or more.
The inherit property in CSS is a tricky one. One of my favorite ways to use it is to set box-sizing.