Lina, yes, I will take a look at this tomorrow (I think it's probably late for you right now too).
But, I'm finding something really strange - I can't explain this. On your 'main' page the body tag looks like this:
<body id='exhibit-1' class='section-1'>
While on any other page you will see something like this:
<body class='exhibits section-1 exhibit-70 format-horizontal'>
It's like you are using the wrong template for the main? Are you using "index.php" or something you created yourself?
It should be reporting the "format-$exhibit_format" in the body tag. This, is really strange...