Recently active topics in Dipity tagged with ie7 javascript embed margin

IE7 (IE 7, Internet Explorer 7 for the search engine) doesn't seem to respect Javascript settings.
At http://blogs.guardian.co.uk/technolog... the settings are for a width of 440px, but IE7 displays it with a spill into the RH margin. Other browsers (Camino, Safari: I'm on a Mac, the complaints from a Windows user) seem to respect it.

Is this a problem of (1) Movable Type for the blog not having good enough CSS (2) IE7 not having good enough CSS (3) Dipity's embed not having good enough CSS (4) something altogether else?