Browser detection for IE 4 and Netscape 4

Version 4 browsers have limited and somewhat erratic support for CSS. Making a CSS layout in these browsers, whose market share has now slipped well below 1%, can be extremely challenging. It's become common practice nowadays to completely hide the CSS file from version 4 and earlier browsers. This can be achieved using the @import directive to call up the CSS document:

Version 4 (and earlier) browsers will display a non-styled version of the site as they can't understand this @import directive.