Keep consistent text size on mobile orientation change

using vendor-specific CSS `*-text-size-adjust`.

ui/static/css/common.css

@@ -5,6 +5,11 @@
     box-sizing: border-box;
 }
 
+html {
+    -webkit-text-size-adjust: 100%;
+    -ms-text-size-adjust: 100%;
+}
+
 body {
     font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
     text-rendering: optimizeLegibility;