edit pass on T3,4,5, updated images

src/site/docs/tutorials/connect-dart-html/examples/mini/mini.css

 
 body {
   background-color: #F8F8F8;
   font-family: 'Open Sans', sans-serif;
   font-size: 14px;
   font-weight: normal;
   line-height: 1.2em;
   margin: 15px;
 }
 
 h1, p {
   color: #333;
 }
 
 #sample_container_id {
   width: 100%;
   height: 400px;
   position: relative;
   border: 1px solid #ccc;
   background-color: #fff;
 }
 
 #sample_text_id {
   font-size: 24pt;
   text-align: center;
   margin-top: 140px;
 }