[css-sizing-3] Fix tabs versus spaces bikeshed warnings.

Author: dbaron

css-sizing-3/Overview.bs

@@ -513,8 +513,8 @@ Sizing Values: the <<length-percentage [0,∞]>>, ''width/auto'' | ''max-width/n
 			with the <a>available space</a> replaced by the specified argument,
 			i.e.
 			<code>min(''width/max-content'', max(''width/min-content'', <<length-percentage>>))</code>,
-            where the <<length-percentage>> argument is resolved
-            exactly as for <<length-percentage>> values standing alone.
+			where the <<length-percentage>> argument is resolved
+			exactly as for <<length-percentage>> values standing alone.
 
 			Negative <<length-percentage>> values are invalid.
 	</dl>
@@ -1315,7 +1315,7 @@ Compressible Replaced Elements</h4>
 	in <a href="https://html.spec.whatwg.org/multipage/rendering.html#replaced-elements">HTML&sect;14.4</a> [[!HTML]],
 	the following HTML elements are also considered to be [=replaced elements=]
 	for the purpose of the <a href="#replaced-percentage-min-contribution">percentage-sized replaced element rule</a> above,
-    and can have their <a>min-content contribution</a> compressed
+	and can have their <a>min-content contribution</a> compressed
 	when their 'width'/'height' or 'max-width'/'max-height'
 	is expressed with a cyclic percentage size: