images in theme files won't show

I’m trying to build a theme with a few hardcoded images- background, social share buttons, and logo.

Live site.

Here are examples of the code I’m using:
index.php

<div id="stay-in-touch">
	<p>Stay in touch-</p>
	<ul>
		<li><a href="#"><img src="img/facebook.png" alt="Like on Facebook" /></a></li>
		<li><a href="#"><img src="img/twitter.png" alt="Follow on Twitter" /></a></li>
		<li><a href="#"><img src="img/linkedin.png" alt="Connect on LinkedIn" /></a></li>
	</ul>
</div><!-- end stay-in-touch -->

style.css

body {
	background: url('img/background.png');
	-webkit-background-size: cover;
	-moz-background-size: cover;
	-o-background-size: cover;
	background-size: cover;
	font-family: Arial, "Helvetica Neue", Helvetica, sans-serif;
}

I thought maybe it was something to do with the host and permissions, but everything seems fine on that end. Any and all help is greatly appreciated.