added front page samples to testing, plus a couple of tweaks to front page and code lab

src/site/css/dart-style.css

 
 body {
         font-family: 'Roboto', sans-serif;
     -webkit-font-smoothing: antialiased;
 }
 
 /* ***** General ***** */
 p {
   font: 400 15px/19px 'Roboto', sans-serif;
   color: #484848;
@@ skipping 467 matching lines @@
 }
 
 .dart-carousel .carousel-inner > .item > img {
         margin: 0 auto;
 }
 
 /* ***** Code ***** */
 .code-hldr {
         text-align: center;
         min-height: 450px;
+        height: 450px;
 }
 
 .lang-dart, .lang-html {
   max-width: 800px;
   text-align: left;
   margin-right: auto;
   margin-left: auto;
   padding: 5px !important;
 
   -webkit-box-shadow: 0 5px 18px -7px rgba(0, 0, 0, 0.2);
@@ skipping 791 matching lines @@
 
 .good pre.prettyprint {
   background-color: #f8fff8;
 }
 
 .good pre.prettyprint:before {
   content: "good";
   color: #696;
   float: right;
 }