Hi
Not sure if this will help, but the way I see it you have two options.
You can either remove the blog description completely which you probably don't want to do, but will definetely look fine, or you need to bump the description down a few pixels.
The code to do this will need to be inserted into the default.css file which is located in library/styles of the thematic theme folder.
you need to locate:
#blog-description {
font-style:italic;
padding:8px 0 63px 0;
color:#fff;
}
and change the 8px to something like 70px or therabouts.
eg.
padding:70px 0 63px 0;
Also another thing that would be worthwhile changing is removing that black line that goes right through your logo.
find the following code (should be just above the code you've just edited)
#blog-title {
font-size:36px;
line-height:54px;
font-weight:bold;
letter-spacing:-1px;
padding:99px 0 0 0;
border-bottom:1px solid #242A30;
}
and delete the line
border-bottom:1px solid #242A30;
Hope this has helped you.
Mikey