Embedded reports not scaling correctly in Dreamweaver created site

Embedded reports not scaling correctly in Dreamweaver created site

An interesting one this one. I built a site with ten embedded Zoho reports. This was a very simple site and worked just fine. I adjusted the iFrames to 600 x 500 and the ZoHo content scaled perfectly.

I then decided to do a better job based on CSS using Dreamweaver CS 5.5 (don't ask) and the reports did not NOT then scale properly and were elongated only showing about a quarter of the bar charts in the vertical direction. Actually it was very browser dependent - the only common thing was that no bvrowser worked correctly with the ZoHo iFrame reports.

After a few hours of tearing my hair out, I discovered that removing the Dreamweaver-generated DOCTYPE statement below at the head of the pages, all returned to normal and the ZoHo reports then scaled correctly.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

Can anyone please explain this as I've never come across this sensitivity before.

Chris