Fix minor typo ("thatm") in spec

index.html

@@ -610,7 +610,7 @@ <h2 class="heading settled heading" data-level=3 id=usecase><span class=secno>3
 	<figcaption>An example of a self-contained module that requires a single breakpoint.</figcaption>
 </figure>
 
-<p>In our example site’s homepage layout this module can occupy containing elements of varying widths, governed by multiple breakpoints. In small viewports, we’ll be using a linear layout where each of our five module occupies the full viewport—this layout is covered by the base styles outside of our <a href=http://dev.w3.org/csswg/mediaqueries-4/#media-query>media query</a>. At higher breakpoints, these modules will be displayed side-by-side: three across, then below thatm two across. The three-across layout will be covered by the global styles within our viewport-based media query. Parent-specific overrides will need to be written for the two-across layout, as these modules will need to shift to their wide-format at a smaller viewport size than the ones above them.</p>
+<p>In our example site’s homepage layout this module can occupy containing elements of varying widths, governed by multiple breakpoints. In small viewports, we’ll be using a linear layout where each of our five module occupies the full viewport—this layout is covered by the base styles outside of our <a href=http://dev.w3.org/csswg/mediaqueries-4/#media-query>media query</a>. At higher breakpoints, these modules will be displayed side-by-side: three across, then below that two across. The three-across layout will be covered by the global styles within our viewport-based media query. Parent-specific overrides will need to be written for the two-across layout, as these modules will need to shift to their wide-format at a smaller viewport size than the ones above them.</p>
 
 <figure id=fig-2>
 	<img src=images/eq-layout1-modules.gif>