box sizing style (thanks @hugurp)

index.html

@@ -13,6 +13,12 @@
         font-weight: normal;
         font-style: normal;
       }
+      html {
+        box-sizing: border-box;
+      }
+      *, *:before, *:after {
+        box-sizing: inherit;
+      }
       body {
         font-family: 'charterregular', Georgia, serif;
         font-size: 18px;