Hello, I have just installed Xenforo for one of my clients and bought the Lanthanum theme for him today. I have just installed it and it's looking pretty weird with some stuff missing etc. If you would be able to check it out it would be greatly appreciated. here is the link to his new forums http://lpwithpaul.net/Forums/index.php Here you can see what it looks like aswell http://prntscr.com/iphsnj As you can see the header bits are expanded and there is no background image and it looks nothing like its displayed in the preview for the theme.
You can access to Appearance > Styles > Lanthanum > Style Property Groups > Header and Navigation to change the logo, access to Appearance > Styles > Lanthanum > Style Property Groups > [Stylium] Setting to change background.