Microsoft's Internet Explorer 3
The first commercial browser with support for CSS was Microsoft's Internet Explorer 3. This browser was launched in August 1996, and back then the CSS1 specification was not yet a W3C recommendation. Internet Explorer 3 supported most of properties for color, background, text and font, but due to late changes in CSS1 this browser did not implement much of the CSS box model.
Netscape's Navigator 4.0
Microsoft's Internet Explorer 4
In Internet Explorer 4, the old browser display engine was replaced with a module called Trident. A browser display engine does a lot of things and one of them is rendering CSS. The change to Trident removed a lot of the limitations known from Internet Explorer 3, but Trident simultaneously brought along its very own set of limitations – and bugs. Internet Explorer 4 did not have full support for CSS1, but it could display both static documents and handle dynamically changing stylistic properties.
Opera was the third browser to support CSS. Released in November 1998, Opera 3.5 was small enough to fit on a floppy disc yet included support for most features offered by significantly larger browsers such as Explorer and Netscape. Opera 3.5 supported most of CSS1, and the developers had made sure to test run the implementation before the browser was launched.