Update demo appearance

public/aura-demo.css

@@ -2,13 +2,25 @@
 
 /** Styles for component demo, not related to the components itself **/
 
-a:hover {
-	text-decoration: underline;
+body {
+    margin: 0;
 }
 
 #common-area {
-    text-align: center;
     margin-bottom: 100px;
+    padding: 16px 32px;
+    background-color: rgba(0, 0, 0, 0.88);
+    color: white;
+    font-family: Helvetica, sans-serif;
+}
+
+body > *:not(#common-area) {
+    margin: 24px;
+}
+
+#common-area img#aura-logo {
+    filter: invert(1);
+    margin: 0 0 8px 0;
 }
 
 #common-area h1 {
@@ -17,14 +29,9 @@ a:hover {
 }
 
 #common-area p {
-    margin: 0 30%;
-    text-align: justify;
-}
-
-ul.aura-demo-menu {
-    list-style: none;
+    max-width: 400px;
 }
 
-#aura-logo {
-    margin: 0 0 42px 0;
+#common-area a:hover {
+	text-decoration: underline;
 }
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