Cascading style sheets were formally introduced by the W3C in 1997 and in the nine years since have made gradual progress to becoming a web standard. Although the W3C mandates style sheets instead of HTML formatting for internal styles, many web designers have been slow to adopt CSS. Graphic designers, especially, have been slow to accept CSS since it does not allow the complex designs made possible by the use of nested tables without concentrated testing and workarounds. That is because CSS is not universally cross-browser compatible. The first release of CSS in 1997 was notorious for breaking on a variety of browsers. The second, and current, release provides more stability but still causes unexpected results on older browsers. In light of the cross-browser difficulties of CSS. many designers have adopted a hybrid standard, using CSS for styling text but continuing to use nested tables to structure their pages. This provides a measure of stability and control to a web designer who does not have the time or inclination to learn advanced CSS. However, this practice is severely frowned on by both the W3C and by a small but influential group of CSS designers who claim that the use of nested tables slows down page loading and that CSS can, with proper application, create complex designs just as well as nested tables. However, many freelance web designers have found that their clients are unwilling to accept the additional cost and time to create a completely CSS-based design. This attitude is beginning to change at the corporate level, however, as more and more sites are redesigned using pure CSS. The continuing acceptance of CSS as a web standard has also been hampered by the popularity of Macromedia Flash as a design tool. Completely vector-based and imported into a web page by the use of a plug-in, Flash offers enormous flexibility in creating complex navigation systems, a historically weak point of CSS. Flash also allows a higher level of artistic expression than the more limited CSS, which is primarily designed to deliver information. This has created a divide in the web design community to the point where there are basically two camps of web designers, those who use Flash and those who don't. The debate over the merits of CSS versus Flash has been known to get quite heated on occasion. Many have predicted that the third release of CSS will solve many of the problems hampering widespread acceptance of CSS as a web standard. However, the third release has been in development since 1998 and is not expected to be completed anytime soon.