I have a site done and called the client to take a look at it. It validates perfectly, I have checked it in IE 5.5, 6.0, 7, 8, FF and Chrome on my machines. Looks fine.

Test site is here. Client takes a look using IE 8 and says the phone numbers in the head show in two lines instead of one as in:
941
xxx-xxxx

He says the same thing for the Lic# in the footer, that also displays on two lines.

I called someone and asked them to look at the site and they said it displays fine. Does anyone have an idea why this would happen.

Thanks for looking.

OK, got to the bottom of the issue. The client had his text size set to largerst. That caused the problem.

Can someone tell me how to avoid this issue in the future? I made the header using em instead of px. Was that a mistake?

I made the header using em instead of px. Was that a mistake?

Nope. The problem is the div the numbers are in are a fixed width, so when the text is made larger, there's no room for expansion.

Thanks, I changed that div.