Cnut seems to have been playing with the CSS code that controls the layout, and some change they made seems to be reacting poorly with Firefox 188.8.131.52. I do pity the poor Cnut web developers. IE6's CSS is so broken and incomplete, it's a wonder people can get anything done with it at all. Trying to get a page to look even remotely similar in IE and any standards compliant browser (i.e. all non-IE browsers) is a real pain.
However, a quick once over of the generated source for these pages, it seems the Cnut web developers are ignoring one of the key features of CSS. So key, it's the C in CSS: Cascading. You can create two stylesheets, one for IE, one for standards compliant browsers, and through the use of an IE specific tag, you can let the IE rules override the standards complaint ones where IE's implementation is broken.
It does seem just a little embarrassing, if you ask me, when a self-styled technology leader site can't seem to figure out some of the basics of web design. Kind of shoots what little credibility Cnut has among non-PHB types straight to hell. I know it's a pain, it's why I hate doing web development, but it's just inexcusable for a commercial site. Even more so when it's a site that likes to think itself as the educator of the clueless masses. Makes it look like a case of the blind leading the blind.