H1's are floating into post above in Wordpress theme

H1's are floating into post above in Wordpress theme

I just noticed that on the Wordpress theme I created the H1 article titles
are floating up into the subsequent article when you start to shrink the
browser window. I can't seem to find the reason for this. Any insights
would be greatly appreciated.
ul.info li, .excerpt, .post-link {
float: left;
}
The styles above seem to be pushing the title of the article up but if I
remove it then "posted by, written on, date" all turn into a horizontal
list. Which I don't want.
I don't know if they're related by I noticed when I look at single post
pages if I shrink the browser window the content of the article flows off
the screen.
Thanks in advance for you help everyone. Really confused.