div usage in asp and aspx

I think I'm just not understanding the usage of div in asp and aspx. I have a form that i want to hide certain elements when certian actions occur. If is have a div wrapping around what i want to hide ..

<div id='div1' Visible="true" RunAt="Server">
<select name="location">
<option selected>choose option</option>
<option>Yes</option>
<option>No</option>
</select>
</div>

and then call a java funtion to set div1.visible to false.

function voda() {
document.getElementById('div1').style.visible='false'
}

It will hide it if it's and aspx file, but if it's an asp file, it's just always visible and I can't get it off the form. Is there a different syntax I need to use when working with just a plain asp file?

secondly, on some servers the aspx file will run fine, and on others it will ask if you want to download it instead of just running the page, does the asp interpreter need to be upgraded on those servers to deal with the newer aspx files?

the code displayed is simplified, there was a <li> tag in the div originally, and that superceeds the div tag so i can't just make that disappear, which is really not very smooth of ASP. If anyone else has any sugguestions feel free to make some.

The .NET framework needs to be installed to run .aspx pages.

I don't believe asp3 supports any Runat=Server in a div tag.