Problem with footer in a master page

[guoyuanliu]

I have a .NET master page which have the overall design of header and foote, with the content dynamically change size depends on data retrieved from Database.. The problem is.. when the data grows.. the footer is not showing !
I have set the following CSS rule to the footer's div element

#footer
{
position: relative;
top:250px;
clear: both;
min-height:66px;
height: 66px;
text-align: center;
line-height: 66px;
left: 0px;
width: 95%;
}

this is the html organization for the content and the footer

<div id="all">
................
<div id="content">
.......... [content]
</div>
<div id="footer">
Copyright
</div>
</div>


Any help would be appreciated, thanks !