improve(css): increase text size on larger screens.

Author: chriskrycho

src/styles/app.scss

@@ -9,6 +9,16 @@ $green: #398277;
 $purple: #403D58;
 $yellow: #FFD45E;
 
+html {
+  font-size: 62.5%
+}
+
+@media screen and (min-width: 30em) {
+  html {
+    font-size: 75%;
+  }
+}
+
 body {
   font-family: $body-font;
   background-color: white;