Form margins : how to get rid of them

In ruby on rails i try to force the from_tag to have a margin of 0 but
it doesn't seem to work. Forms always seem to have a margin inside a
table.

<td><% form_remote_tag :url => {:controller => "sgpanel", :action =>
"remove_from_cart", :id => product.id,:ad => product.sguser_id, :class
=> "formnomargin"} do %>
<%= submit_tag "Remove item" , :class => "medium" %>

input.formnomargin
{
padding:0;
vertical-align: bottom;
margin:0;
}

input.medium
{
font-size:12px;
width:85px;
padding:0;
vertical-align: bottom;
margin-bottom:0;
}

the default display mode of a form emlement is block, put it inline
form{display:inline}