Internet Explorer 7 (IE7) will be released in the next few months and, in all likelihood, it will be most peoples default browser within a year or two. Given the huge number of people currently using IE6 this large migration of users would be in and of itself noteworthy, but its the qualitative rather than quantitative aspect of this changeover thats perhaps most significant. A lot of CSS driven websites are not going to work properly on IE7.
The quirkiness of IE6 has meant that designers have had to hack and slash their way through CSS coding in order to make IE6 behave. Microsoft, however, has seen the light and has now created a sleek and shiny rendering engine for IE7 with much better support for CSS. The problem is that the CSS hacks that previously exploited IE6s lumbering CSS parsing, will no longer work with the more lithe IE7. This means that its time to develop new tactics in our CSS development.
The first thing to note is that the rendering engine in the current Beta version of IE7 will perform as the final product will, so its time to install IE7 and start testing your sites in the new browser. To facilitate this, the IE7 team has deliberately given people a period of grace to acclimatize to the new environment; the browser is available now and you can start testing right away in anticipation of the actual release date.
In addition to this, the IE team has suggested that we no longer use CSS hacks targeted at IE specifically, and that instead we use conditional comments to serve specific inline CSS or files to IE. An example of this would be:
Where previously you might have used this: * html #selector { margin: 5px; }]]>
The changeover to IE7 need not be an ordeal. By testing early and giving up on the old IE parsing bug hacks in favor of using IE specific CSS, the transition to IE7 should be as smooth as possible, helping you and your customers reap the benefits of the new browser.