Adding the wrong type of content can easily break your blog template.
All during today I have been worrying about my blog template being broken. I had been playing with it slightly, but nothing serious.
The broken formatting was only showing up in Internet Explorer, and because I use Firefox 95% of the time, I hadn't noticed it.
I am not up to speed on CSS enough to spot anything more than a glaring error, and couldn't see anything wrong.
It turned out that a table I had cut and pasted into my blog from a website was to blame. The offending post has now been moved to the drafts section for some cleaning up.
So be careful what content you copy from normal websites, because it can be a mass of HTML tables used for formatting, and some browsers handle them differently to others when combined with CSS forms used in blogs.