body {
    background-image: url('obrazky/mainpagebackground.png');
    background-size:100%;
    width:100%;
    height:100%;
    
}
#odkaz {
    
    position: fixed;
    left: 45%;
   
    top: 50%;
    
   
}
#htmlodkaz {
    font-size: large;
    font-family: Arial;
    text-decoration: none;
    color: deepskyblue;
    background-color:oldlace;
    
}
#htmlodkaz:hover{
    background-color:black;color:white
    
}
#mainobr {
    position: fixed;
    bottom:4%;
    left:50%;
}