PUBLIC MARKS with tags best & css

When editing userChrome.css, you must add CSS selectors based on the element names and IDs/classes of the XUL user interface. There is no comprehensive listing of every single possible selector to use when styling the user interface (just as it would be silly to create such a comprehensive list for a web page), but a few of the more common and interesting selectors are listed below. The best way to discover how to select an element in the user interface is to use the DOM Inspector.

@supports Usage : In most cases, the best usage of @supports is setting an older set of styles as backup and then canceling those styles out and enhancing if a given property is supported. One brilliant use case for @supports is layout. Some edge browsers are now providing support for flexbox while others lag behind.

Presenting scripts that are lightweight, unobtrusive, practical, well-documented and easy to implement. Providing tutorials with practical problem solving information.