My 404 page is breaking, anyone know why?

Hello,
I’ve made my own WordPress theme (using Toolbox theme and reworking it a bit) and I’ve got most things done the way I’d like. I still have a few issues, things seem to break in IE a little (everything looks great in Chrome/Safari!), but one I don’t understand at all. My 404 page completely breaks the layout of my header and widget area, and I have no idea why. Have a look: https://terraavocado.com/givemea404

The code for 404.php is just this:

<?php
/**
 * The template for displaying 404 pages (Not Found).
 *
 * @package WordPress
 * @subpackage Toolbox
 * @since Toolbox 0.1
 */

get_header(); ?>

	<div id="primary">
		<div id="content" role="main">
			<article id="post-0" class="post error404 not-found">
				<h1 class="entry-title-page nomargins">Never order off menu</h1>
					<div class="entry-content">
						<p>Whatever you&rsquo;re looking for can&rsquo;t seem to find itself. Try searching for it, or if you have found this after following a broken link, please tell me so I can fix it!</p>
					</div><!-- .entry-content -->
			</article>
		</div><!-- #content -->
	</div><!-- #primary -->

<?php get_footer(); ?>

So I am a little confused as to why everything gets messed up. Anyone have an idea? Thanks!