PUBLIC MARKS from decembre with tags css & user

userChrome.css is a style sheet with special importance to Firefox. The rules in userChrome.css are applied to the user interface, and can override nearly every built-in style rule. Unfortunately, you cannot use userChrome.css to change the functional operation of Firefox; that's what extensions are for. Creating a userChrome.css file and adding style rules allows you to make changes to fonts and colors, hide unnecessary items, adjust spacing, and make other changes to the appearance of Firefox. The following examples illustrate the wide range of effects you can create, either by creating your own style recipes, or building on the work of CSS wizards sharing their talents on the web.

The addon directory in the distribution contains a number of reusable components that implement extra editor functionality

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.

Lazy Load is delays loading of images in long web pages. Images outside of viewport are not loaded until user scrolls to them. This is opposite of image preloading. Using Lazy Load on long web pages will make the page load faster. In some cases it can also help to reduce server load.