[css-text-4] Fix markup

Closes w3c#3206

Author: frivoal

css-text-4/Overview.bs

@@ -1034,7 +1034,7 @@ Line Start/End Padding: the 'line-padding' property</h3>
 			span { background: black; color: white; }
 			em   { background: green; color: white; }
 
-			<p><span>Here is <em>some text</em></p>
+			<p><span>Here is <em>some text</em></span></p>
 		</xmp>
 
 		Line-padding will be inserted such that
@@ -1053,7 +1053,7 @@ Line Start/End Padding: the 'line-padding' property</h3>
 		</style>
 		<pre class="figure" id="line-padding-rendering">
 			<span>Here is <em>some</em>
-			<em>text</em>
+			<em>text</em></span>
 		</pre>
 	</div>
 
@@ -1551,4 +1551,4 @@ Changes</h2>
 		<li>Redefine ''text-wrap: balance'' in terms of remaining space.
 		<li>Note various issues on ''text-wrap: <<string>>''.
 		<li>Miscellaneous minor fixes.
-	</ul>
+	</ul>