z-index
Widely available since 2018-01-29
The z-index CSS property orders overlapping elements, with higher values appearing in front of or on top of lower values.
Learning resources on MDN
Browser support
- Chrome 1 Released on 2008-12-11
- Chrome Android 18 Released on 2012-06-27
- Edge 12 Released on 2015-07-29
- Firefox 3 Released on 2008-06-17
- Firefox for Android 4 Released on 2011-03-29
- Safari 1 Released on 2003-06-23
- Safari on iOS 1 Released on 2007-06-29