Spook,
I sort of like the blue-ish theme, but you can change thing Take a look at
/home/httpd/html/horde/config/pref.php and you will see a section where you can set the theme.
// UI theme
$_prefs['theme'] = array(
'value' => 'bluewhite',
'locked' => false,
'shared' => true,
'type' => 'select',
'desc' => _("Select your color scheme.")
);
Select a theme from the themes directory and set it as the value. The preloaded themes are here:
/home/httpd/html/horde/
Of course, you will need to make this permanent by creating the appropriate custom-templates. Let me know if you need a hand with that.