How to adapt the wordpress theme resolution to the user's screen resolution

Hello,
I have a problem. One week ago, i buyed a wordpress template for my website (www.dipsy.ro) wich i liked in the preview of the seller’s presentation. The problem is that when i installed it on my website, it looks like … low resolution. In my wordpress admin account i didn’t find any way to set that resolution and i am very unhappy with this: button texts are too big, they overcross each other, the pages’ titles are not like in the preview i saw when i buyed the theme. It is like i would run an OS at low resolution on my wide screen.
If anyone can help me, i would appreciate it very much.

Here is a link to the seller’s preview of the theme. Please consider to compare it with my website look and try to give me a reasonable advice about how to handle this problem. You can also see another differences, wich i would like to solve…

http://www.templatemonster.com/demo/31673.html
and
http://www.templatemonster.com/wordpress-themes/31673.html