add example form styles and a testing class

relates #23 #25 #29

public/css/style.css

@@ -0,0 +1,30 @@
+/**
+ * The CSS shown here will not be introduced in the Quickstart guide, but shows
+ * how you can use CSS to style your Element's container.
+ */
+.StripeElement {
+  background-color: white;
+  padding: 8px 12px;
+  border-radius: 4px;
+  border: 1px solid transparent;
+  box-shadow: 0 1px 3px 0 #e6ebf1;
+  -webkit-transition: box-shadow 150ms ease;
+  transition: box-shadow 150ms ease;
+}
+
+.StripeElement--focus {
+  box-shadow: 0 1px 3px 0 #cfd7df;
+}
+
+.StripeElement--invalid {
+  border-color: #fa755a;
+}
+
+.StripeElement--webkit-autofill {
+  background-color: #fefde5 !important;
+}
+
+.test{
+  background-color: red;
+  min-height: 800px;
+}