increase alpha value for better visibility

from 0.2 to 0.6

Author: glmvc

learn/tasks/values/color.html

@@ -43,7 +43,7 @@
           <li class="hex">hex color</li>
           <li class="rgb">RGB color</li>
           <li class="hsl">HSL color</li>
-          <li class="transparency">Alpha value 0.2</li>
+          <li class="transparency">Alpha value 0.6</li>
         </ul>
     </section>
 
@@ -70,7 +70,7 @@
   <li class="hex">hex color</li>
   <li class="rgb">RGB color</li>
   <li class="hsl">HSL color</li>
-  <li class="transparency">Alpha value 0.2</li>
+  <li class="transparency">Alpha value 0.6</li>
 </ul>
     </textarea>