Update style.css

style.css

@@ -6,6 +6,14 @@ body {
 	background: #f5f5f5;
 }
 
+.banner img {
+    width: 100%;
+    max-width: 600px;  /* Adjust this value */
+    height: auto;
+    display: block;
+    margin: 0 auto;  /* Centers it */
+}
+
 .card {
 	max-width: 900px;
 	margin: 0 auto;