overflow auto for <section> in mobile too

public/app.css

@@ -48,6 +48,10 @@ nav ul li a {
 	border:1px solid black;
 }
 
+main > section {
+	overflow:auto;
+}
+
 @media (min-width: 900px){
 
 	nav {
@@ -61,10 +65,6 @@ nav ul li a {
 		grid-template-rows: repeat(2, minmax(10px, 1fr));
 	}
 
-	section {
-		overflow:auto;
-	}
-
 	#timer { grid-area: 1 / 1 / 3 / 2; }
 	#summary { grid-area: 1 / 2 / 3 / 3; }
 	#category { grid-area: 1 / 3 / 2 / 4; }