Techniques for determining iphone vs. ipad CSS rendering problems?

I have a glaring CSS problem with my 开发者_如何转开发website on iphone even though it looks just fine in safari for mac and safari for ipad.

In the attached screens, notice the white background in the upper right corner is only present on the iphone (and it's not supposed to look that way).

What tools and or techniques would you use to try and isolate the cause of this rendering problem?

Here's the iPad version that's OK.

Here's the iPhone rendering of the same page with the extraneous white area in the upper right.

And for easy clicking.. the site is http://summertown.org/

tia!

-Darrell

My problem is solved. One of my super smart co-workers took pity on me and gave me the CSS fix. I'm not any smarter on HOW he figured this out... he said it was a trade secret.

Anyway, the solution was to add...

“min-width: 57.69em;” 

to body css (summertown.css)