[css-sizing-3] Typos and wording tweaks. ixes #2315

Author: fantasai

css-sizing-3/Overview.bs

@@ -158,7 +158,7 @@ Terminology</h2>
 Auto Box Sizes</h3>
 
 	There are four types of automatically-determined sizes in CSS
-	(sizes resulting fromy ''width/auto'' sizing rules, depending on context):
+	(sizes resulting from ''width/auto'' sizing rules, depending on context):
 
 	<dl export>
 		: <dfn>stretch-fit size</dfn>
@@ -224,7 +224,7 @@ Auto Box Sizes</h3>
 		: <dfn>fit-content size</dfn>
 		: <dfn>fit-content inline size</dfn>
 		: <dfn>fit-content block size</dfn>
-		:: If the <a>available space</a> in a given axis is finite,
+		:: If the <a>available space</a> in a given axis is <a>definite</a>,
 			equal to <code>min(<a>max-content size</a>, max(<a>min-content size</a>, <a>stretch-fit size</a>))</code>.
 			Otherwise, equal to the <a>max-content size</a> in that axis.
 
@@ -521,8 +521,8 @@ Inner vs Outer Sizes: the 'box-sizing' property</h3>
 	</pre>
 
 	The 'box-sizing' property switches the box model
-	between asssigning finite sizes such as <<length>>s and <<percentage>>s
-	to either the <a>content box</a> or <a>border box</a>.
+	between assigning fixed sizes such as <<length>>s and <<percentage>>s
+	to the <a>content box</a> and the <a>border box</a>.
 	It affects the interpretation of all <a>sizing properties</a>,
 	including 'flex-basis'.