[css-position] 'front' & 'back' keywords for z-index #2444
Description
https://drafts.csswg.org/css-position-3/#propdef-z-index
How many times have you written things like z-index: 999999 or z-index:-999999?
If you work on the design side of the field you may be familiar with phrases like "bring to front" or "send to back" and though it doesn't take too long to understand layering in browsers (I think most of it's nuances were beat like a dead horse in articles 5 to 6 years ago, just google 'css stacking context'), I think people either know and set their sequence of z-index values meticulously OR they just want to send something to the front or back.
So why not support a simple (not as easily broken as 999 or 9999) set of the keywords front & back that explicitly accomplish the task they are named for, while still honoring their place in the local stacking context and document order?