radically simplify the challenge show view and remove the animation

views/challenges/show.jade

@@ -3,16 +3,10 @@ block content
     .row
         .col-sm-12.col-md-8.col-xs-12
             .panel.panel-primary
-                .panel-heading Challenge: #{name}
+                .panel-heading #{name} (takes #{time})
                 .panel.panel-body
-                    .challenge-brief
-                        h3.text-center
-                            span.ion-android-clock
-                            span Takes about #{time}
-                        .btn.btn-primary.btn-big.btn-block.start-challenge Start the challenge
-                    .challenge-content.hidden-element
-                        .responsive-container
-                            iframe(src='//player.vimeo.com/video/#{video}', frameborder='0', webkitallowfullscreen='', mozallowfullscreen='', allowfullscreen='')
+                    .embed-responsive.embed-responsive-16by9
+                        iframe.embed-responsive-item(src='//player.vimeo.com/video/#{video}')
                     h3 Steps:
                     h4
                         ol