Duplicating this CSS for another control

I've bought this template
http://themeforest.net/item/unite-html-business-magazine-community-site/full_screen_preview/84401

and if you scroll down, there's a button. The CSS for it is button.btn and it renders as such

<button type="submit" class="btn"><span>Sign me up!</span></button>

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I've used an ASP.Net login control that renders like this

     
 

<input type="submit" name="Login1$Login" value="Sign In" id="Login1_Login" class="btn">

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So I created a new CSS but mine renders as a standard submit button (those grey buttons) with a black line in the middle. See attached screenshot. So, what did I miss?

input.btn 
{
    padding: 0 28px 0 0; 
	margin-right:5px; 
	font-size: 1em; 
	text-align: center; 
	position: relative;
	cursor: pointer;
	overflow: visible;
	background: transparent url("../images/button-sprite.gif") no-repeat right -92px; }  

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Doc1.docx