[css-values-4] Fix example.

Author: tabatkins

css-values-4/Overview.bs

@@ -2670,16 +2670,16 @@ Exponential  Functions: ''pow()'', ''sqrt()'', ''hypot()''</h3>
 		<pre class=lang-css>
 		:root {
 			--h6: calc(1rem * pow(1.5, -1);
-			--h5: 1rem;
-			--h4: calc(1rem * pow(1.5, 2);
-			--h3: calc(1rem * pow(1.5, 3);
-			--h2: calc(1rem * pow(1.5, 4);
-			--h1: calc(1rem * pow(1.5, 5);
+			--h5: calc(1rem * pow(1.5, 0);
+			--h4: calc(1rem * pow(1.5, 1);
+			--h3: calc(1rem * pow(1.5, 2);
+			--h2: calc(1rem * pow(1.5, 3);
+			--h1: calc(1rem * pow(1.5, 4);
 		}
 		</pre>
 
-		...rather than writing out the values in pre-calculated numbers like ''7.6rem''
-		(what ''calc(1rem * pow(1.5, 5))'' resolves to)
+		...rather than writing out the values in pre-calculated numbers like ''5.0625rem''
+		(what ''calc(1rem * pow(1.5, 4))'' resolves to)
 		which have less clear provenance when encountered in a stylesheet.
 	</div>