Just wanted to add, that I changed recently from using borders to using the “outline” attribute, it works the same way as border (incl. shorthand –> outline: 1px solid black;) but doesn’t add to the box model, means it overlays the let’s say div and doesn’t add a 1px line on every side…one problem you will have: outline is supported poorly by browsers…you would have to use opera (Portable Version here: http://www.opera-usb.com/index.htm) or I think Safari does the job too…but basically I like the outlining-elements-idea very much and I use it every singel time I design a site!

I generally change background colors for debugging. Granted, you can’t always see the background color change if its covered with divs or other objects, but its a lighter, more non-intrusive way to see what’s going on.