ASP.NET Panels are expected to render as <DIV> elements, but poking around with Firefox and FireBug the other day I was surprised to see them rendered as single-cell tables. It turns out that, by default, ASP.NET 1.x treats Firefox as a completely incompetent browser that can't even handle <DIV>s properly. Though this sounds like another strike in the browser wars between IE and Firefox, apparently it is an accident of the development schedule of ASP.NET 1.1. Firefox's usage expanded so quickly after its initial release, that ASP.NET's handling of it was quickly out of date. So, ASP.NET 1.1 treats Firefox as a 'downlevel' browser, and assumes it has only basic support for CSS, DOM and Javascript. Fortunately, this can be changed by adding a carefully-tuned <browserCaps> section inside the <system.web> section of web.config or machine.config. Get the <browserCaps> right, and ASP.NET will then treat Firefox as 'uplevel'. Note