diff --git a/static/c4.css b/static/c4.css
new file mode 100644
index 0000000..a74dc49
--- /dev/null
+++ b/static/c4.css
@@ -0,0 +1,60 @@
+body {
+    color: #f0f0f0;
+    background-color: #333;
+}
+
+h1, h1 a  {
+    color: #fcbb06; /* C4 Yellow */
+}
+
+.result {
+    background-color: #202020;
+    border-color: #4d4d4d;
+}
+
+.result:focus {
+    background-color: #202020;
+    border-color: #fcbb06;
+    outline-color: #fcbb06;
+}
+
+.result a {
+    color: #fcbb06;
+}
+
+.note {
+    background-color: #333;
+    font-size: smaller;
+}
+
+.btn.green {
+    color: #020;
+    background-color: #6f3;
+}
+
+.btn.green:hover ,.btn.green:focus {
+    background-color: #3f0;
+}
+
+.btn.red {
+    color: #200;
+    background-color: #f36;
+}
+
+.btn.red:hover, .btn.red:focus {
+    background-color: #f03;
+}
+
+@keyframes blinker {
+    0% { opacity: 1; }
+    40% { opacity: 1; }
+    90% { opacity: 0; }
+    100% { opacity: 1; }
+}
+
+#mapgrid {
+    outline: 2px solid #fcbb06;
+    background: #fcbb0680;
+    animation: blinker 1s infinite;
+}
+