The website I am working on uses an image defined in CSS as the main logo. The html code looks like this:
Something.com | The best something ever
You're not going to get good SEO results if you, first hide the h1, and second use generic phrases inside the h1.
Don't just use the h1 for sizing, you can use classes to style.
H1 tags should contain keyword rich information such as:
Automotive Repair
Automotive repair being the keyword that relates to the particular page I'm theoretically working on.
Hope that makes sense.