html - Why am I unable to place one div below the other div? -

i know sounds simple unable place 1 div below other div , , code

html:

<div id="gamediv"></div> <div class="style"></div> 

css:

.style {     width:728px;     height:90px;     margin-left:auto;     margin-right:auto; }  

after doing ugly hack in css & in first div style able place desired div below first div , css code:

.style{     width:728px;     height:90px;     margin-left:auto;     margin-right:auto;     position:absolute;     bottom:0px;     left:323px; } 

first div style property: <div id="gamediv" style="position:relative;"></div>

for solution working still can't figure out why previous solutions didn't worked, explanation regarding appreciated!!