Add box-sizing to textarea

core/style.css

@@ -50,6 +50,9 @@ table {
 textarea {
 	resize: vertical;
 	width: 100%;
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
+	box-sizing: border-box;
 }
 
 @media only screen and (orientation: landscape) {