Couple of image optimisations

Author: philwareham

src/assets/img/dark-ad-300x250-placeholder.png

@@ -216,7 +216,7 @@ <h3>110% Awesome Websites</h3>
                     </div>
 
                     <div class="showcases showcase-home-r">
-                        <img class="img--showcase" width="318" height="212" alt="Hicks Design website" src="../img/showcase-teaser-318w212h/25.jpg" srcset="../img/25.jpg 2x">
+                        <img class="img--showcase" width="318" height="212" alt="Hicks Design website" src="../img/showcase-teaser-318w212h/25.png" srcset="../img/25.png 2x">
                     </div>
 
                 </section><!-- /.container -->