[css-align-3][editorial] Fixed Bikeshed warnings

Author: SebastianZ

css-align-3/Overview.bs

@@ -1199,7 +1199,7 @@ Alignment Overflow and Scroll Containers</h3>
 	</div>
 
 	<figure>
-		<img src="images/scroll-align-padding.jpg">
+		<img src="images/scroll-align-padding.jpg" width="658" height="404" alt="">
 		<figcaption>
 			Issue: Replace this image with a proper SVG.
 		</figcaption>
@@ -1217,7 +1217,7 @@ Alignment Overflow and Scroll Containers</h3>
 	than the [=in-flow=] content forming the [=alignment subject=].
 
 	<figure>
-		<img src="images/scroll-align-overflow.jpg" alt="">
+		<img src="images/scroll-align-overflow.jpg" width="658" height="404" alt="">
 		<figcaption>
 			Overflow is not part of the <a>alignment subject</a>,
 			even for a <a>scroll container</a>.