Wikimedia Bugzilla is closed!

Created attachment 12383 [details]
New Create account form in IE7 on XP, from SauceLabs session

In the vform (compact vertically-stacked form) layout of the new Agora design, input fields in IE7 are too wide. You can see this in Create account where the input fields are 296 wide but the form is 290 wide; also the repositioned wpCaptchaWord field in the repositioned FancyCaptch has an offsetWidth of 276, not 268.

This is probably because the mw-ui classes use "box-sizing: content-box", and IE7 doesn't support it.
http://stackoverflow.com/questions/2909667/box-sizing-support-in-ie7 suggests *width=290px or conditional CSS for IE7 might be workarounds. It's easiest to acknowledge the bug and move on.