Add article images and improve styling

Author: codebyra

Wireframe/images/branch.png.png

@@ -87,3 +87,18 @@ article {
     grid-column: span 3;
   }
 }
+header {
+  text-align: center;
+  margin: 2rem 0;
+}
+
+header h1 {
+  margin-bottom: 0.5rem;
+}
+
+footer {
+  width: 100%;
+  background-color: white;
+  border-top: 1px solid black;
+  padding: 10px;
+}