Draft of new codelab for review

src/site/css/dart-style.css

 body {
   font-family: 'Roboto', sans-serif;
   -webkit-font-smoothing: antialiased;
 }
 
 /* ***** General ***** */
 p,
 dt,
 dd {
   font: 400 15px/19px 'Roboto', sans-serif;
@@ skipping 1053 matching lines @@
 }
 
 /* Highlighting code annotated with [[highlight]] */
 code.highlight {
   border: 1px solid yellow;
   color: #0084c5;
   background-color: lemonchiffon;
   border-radius: 4px;
 }
 
+/* Strike through code annotated with [[strike]] */
+code.strike {
+  text-decoration: line-through;
+}
+
 /* Center link. */
 .link {
   vertical-align: middle;
 }
 
 /* Maximum scaling for image at 100% */
 .scale-img-max {
   max-width:100%;
   max-height:100%;
 }
@@ skipping 361 matching lines @@
   .synonym nav ul {
     -moz-column-count:1; /* Firefox */
     -webkit-column-count:1; /* Safari and Chrome */
     column-count:1;
   }
 }
 
 .titlepage h3 {
   font: 400 26px/32px 'Montserrat', sans-serif;
 }