Why font-size < 80% will create indentation?

[cpthk]

I have this html page, you may see in the file link above. The body font-size is currently at 70%, this creates indentations for the lines below first line. If I change body font-size to 80%, the indentation is gone. Why is there such indentation if font-size is less than 80%?

Thanks.

I am running on firefox.

File: http://www.mediafire.com/?6prembh6wjas81a