Obviously your style.css file is lacking a lot of important classes. Additionally, all references to your css files are wrong.
Find
<link rel="stylesheet" type="text/css" href="css/screen_styles_gallery.css" />
<link rel="stylesheet" type="text/css" href="css/screen_layout_large_gallery.css" />
<link rel="stylesheet" type="text/css" media="only screen and (min-width:5px;) and (max-width:500px;)" href="css/screen_layout_small_gallery.css" />
<link rel="stylesheet" type="text/css" media="only screen and (min-width:501px;) and (max-width:800px;)" href="css/screen_layout_medium_gallery.css" />
<link rel="stylesheet" type="text/css" href="../../css/coppermine.css"/>
<link rel="stylesheet" type="text/css" href="../themes/pbphotography/style.css"/>
and replace with
<link rel="stylesheet" type="text/css" href="themes/pbphotography/css/screen_styles_gallery.css" />
<link rel="stylesheet" type="text/css" href="themes/pbphotography/css/screen_layout_large_gallery.css" />
<link rel="stylesheet" type="text/css" media="only screen and (min-width:5px;) and (max-width:500px;)" href="themes/pbphotography/css/screen_layout_small_gallery.css" />
<link rel="stylesheet" type="text/css" media="only screen and (min-width:501px;) and (max-width:800px;)" href="themes/pbphotography/css/screen_layout_medium_gallery.css" />
<link rel="stylesheet" type="text/css" href="css/coppermine.css"/>
<link rel="stylesheet" type="text/css" href="themes/pbphotography/style.css"/>