Introduce sky/framework/theme/typography.dart

sky/examples/stocks-fn/stockrow.dart

 part of stocksapp;
 
 class StockRow extends Component {
 
   Stock stock;
 
   static Style _style = new Style('''
     transform: translateX(0);
     display: flex;
     align-items: center;
     border-bottom: 1px solid #F4F4F4;
     padding-top: 16px;
     padding-left: 16px;
     padding-right: 16px;
     padding-bottom: 20px;'''
   );
 
   static Style _tickerStyle = new Style('''
-    flex: 1;
-    font-family: 'Roboto Medium', 'Helvetica';'''
+    flex: 1;'''
   );
 
   static Style _lastSaleStyle = new Style('''
     text-align: right;
     padding-right: 16px;'''
   );
 
   static Style _changeStyle = new Style('''
-    color: #8A8A8A;
+    ${typography.black.caption};
     text-align: right;'''
   );
 
   StockRow({Stock stock}) : super(key: stock.symbol) {
     this.stock = stock;
   }
 
   Node build() {
     String lastSale = "\$${stock.lastSale.toStringAsFixed(2)}";
 
@@ skipping 21 matching lines @@
         children: [new Text(changeInPrice)]
       )
     ];
 
     return new Material(
       style: _style,
       children: children
     );
   }
 }