You can describe color on the screen in a variety of ways, but most of these descriptions are just different ways of telling the computer how much red, green, and blue are in a particular color. Browser-safe Colors? Certain colors always display properly on any monitor. These colors are called browser-safe colors. You’ll find them fairly easy to remember because their values stay consistent. In hexadecimal values, you can use any combination of 00, 33, 66, 99, CC, and FF. In numeric values, use 0, 51, 102, 153, 204, or 255. In percentages, use 0, 20, 40, 60, 80, or 100.

CSS level 2 (CSS2) The CSS2 spec came out in 1998 and is the most widely adopted by browser makers. Level 2 includes all the attributes of the previous two versions, plus an increased emphasis on international accessibility and the capability to specify media specific CSS. In 2006, the W3C published an updated version: CSS Level 2.1, which corrected some errors, clarified a few issues, and included specifications for features that had already been implemented in some browsers. CSS2.1 has effectively replaced CSS2.

CSS level 1 (CSS1) The W3C released the first official version of CSS in 1996. This early version included the core capabilities associated with CSS, such as the ability to format text, set fonts, and set margins. Netscape 4 and Internet Explorer 3 and 4 support Level 1. Web designers needed a way to position elements on the screen precisely. CSS1 was already released, and CSS Level 2 was still in the future, so the W3C released a stopgap solution: CSS-Positioning. This standard proposed that the parties concerned could debate for awhile before the CSS-P standard became official.