Make better use of mixins and extending for responsiveness

- uses textElement() to group together p,h1...h4
- Turns out if you extend a class then say change the class in a media breakpoint it will apply the media queried properties to everything that extends the original class.

index.html

@@ -123,7 +123,7 @@
                 </tr>
             </table>
         </div>
-        <div><a id="skilltablebutton" style="text-decoration: underline; font-size: 1.1em; font-style: italic; font-weight: normal;" onclick="toggleSkillTable()">More about me</a>
+        <div><a id="skilltablebutton" style="" onclick="toggleSkillTable()">More about me</a>
         </div>
     </div>
     <div class="slide">