remove arrow function from index and add breakpoints to css

src/files/index.html

@@ -56,7 +56,7 @@
 	<!-- load selected version of Rollup, then the app -->
 	<script>
 		function loadScript ( src ) {
-			return new Promise( ( fulfil, reject ) => {
+			return new Promise( function ( fulfil, reject ) {
 				var script = document.createElement( 'script' );
 				script.onload = fulfil;
 				script.onerror = reject;

src/styles/blurb.css

@@ -8,9 +8,15 @@
 	clear: fix;
 
 	.block {
-		flex: 1 0 25%;
+    @media (min-width: 60rem) {
+      flex: 1 0 25%;
+      width: 25%;
+    }
+    @media (min-width: 45rem) {
+      flex: 1 0 50%;
+      width: 50%;
+    }
 		padding: 0 0.5em;
-		width: 25%;
 		min-width: 15rem;
 		@media (max-width: 15rem) {
 			min-width: 100%;

src/styles/main.css

@@ -10,8 +10,11 @@ body > main {
 	}
 
 	.left, .right {
-		flex: 1 0 50%;
-		width: 50%;
+    width: 100%;
+    @media (min-width: 45rem) {
+      flex: 1 0 50%;
+      width: 50%;
+    }
 		height: 100%;
 		float: left;
 		overflow-y: auto;
@@ -23,7 +26,9 @@ body > main {
 	}
 
 	.left {
-		border-right: 1px solid #eee;
+    @media (min-width: 45rem) {
+      border-right: 1px solid #eee;
+    }
 
 		/*h2 {
 			text-align: right;