My site looks messed up in IE. What am I doing wrong?

Hello everyone,

I am working on my site www.ministore.sk and I am a total amateur so I would like to ask you guys what am I doing wrong in my CSS code. My site looks fine in Chrome, Mozilla and Opera, but in IE it just looks messed up. Here is my CSS code:

#aroundpage{
position:absolute;
top:120px !important;
}

#header{
visibility:hidden;
}
#site_logo{
visibility:visible;
}

#footer_right{
visibility:hidden;
}

#footer{
visibility:hidden;
}

#footer_center{
visibility:hidden;
}

#topmenu{
bottom: 254px;

What should I add or change so that it looks good in IE as well? Thanks guys!