Better handling of background image.

assets/main.css

@@ -17,19 +17,21 @@ body {
   background-image: url("img/background_main.jpg");
   background-repeat: no-repeat;
   background-position: 50% 35px;
+  background-size: 100%;
   position: relative;
-  min-height: 700px;
+  min-height: 1500px;
   padding-bottom: 200px;
 }
 
 
 body > .jumbotron {
   background-color: transparent;
-  padding: 2em;
+  padding: 3.5em 0;
 }
 
 body > section {
   background-color: #eee;
+  background-color: rgba(250,250,250,0.7);
   padding-bottom: 2em;
 }