fix($default-theme): table tag cannot scroll horizontally (close: #518) (#519)

Author: jonkofee

lib/default-theme/styles/theme.styl

@@ -150,6 +150,8 @@ hr
 table
   border-collapse collapse
   margin 1rem 0
+  display: block
+  overflow-x: auto
 
 tr
   border-top 1px solid #dfe2e5