#centr {width: 900px; position:relative; margin-left: auto; margin-right: auto;}

body {margin: 0px;}

#hlavicka {position:absolute; width: 900px; height:250px; top: 0px; left: 0px;}

#nabidkahl {position:absolute; width: 900px; height: 25px; top: 250px; left: 0px; background-color: #00ff88}

#obsah {position:absolute; width: 900px; left: 0 px; top: 275px;   background-color: #aa33ee}

a:link            {color: white}
a:visited        {color: white}
a:active        {color: green}
a:hover        {color: black}