Nobody wants an ugly, poor-fitting signup form on their website. The problem is, most people don’t know how wide to make their form when they create it, so they just wing it and hope it looks OK.
Fortunately it’s pretty easy to find out what the perfect width is to make it fit nice and tight.
The first thing you need to do is to go to http://getfirebug.com and install Firebug (or Firebug Lite) on your browser.
Then just open Firebug and follow these three steps:
1. Click on the ‘Inspect’ tab.
2. Highlight the sidebar or whatever area that your form will sit in.
3. Find the width.