blockquotes not displaying correctly

I’ve seen a couple of threads that may be related to this but haven’t found a solution…

when I have a blockquote in a post the font & padding are displaying incorrectly.

Please see this post for an example of what is happening:
http://www.stumplane.us/blog/?p=1

Oddly, when I delete the line break before the first blockquote tag the format shows correctly, but when I do that my HTML doesn’t validate.

(Also, my css doesn’t validate and I can’t figure out how to fix it. problems with my background values, so it may or may not be related to this.)

Any help will be appreciated. Thanks.