Thematic Header Image Link

gistfile1.css

#blog-title a {
  display: block;
  height: 200px;
  width: 100%;
  background: url('http://localhost/githubs/test/wp-content/uploads/sites/12/2015/07/cropped-300.jpg');
  margin: 0;
  padding: 0;
  text-indent: -9999px; /* hides blog name, remove if you want the blog text */
}
#blog-description {
  display: none; /* hides blog description, remove if you want blog description */
}