Add WHATWG-themed CSS for nginx directory listings

Relates to #91 and
whatwg/misc-server#79

Author: sideshowbarker

resources.whatwg.org/nginx-fancyindex-whatwg.css

@@ -0,0 +1,40 @@
+html {
+ font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
+  --whatwggreen: #3A7908;
+}
+body { 
+  padding:0;
+  margin:1em;
+}
+a {
+ color: #00F;
+}
+a:visited {
+ color: #0E388C;
+}
+a:hover, a:focus {
+  color:var(--whatwggreen);
+  text-decoration:none;
+}
+h1 {
+  color:var(--whatwggreen);
+}
+table {
+ border:1px solid #aaa;
+ width:100%;
+}
+tr:nth-child(even) {
+  background:#f4f4f4;
+}
+th,td {
+  padding:0.5em;
+}
+th {
+  text-align:left;
+  font-weight:bold;
+  background:#eee;
+  border-bottom:1px solid #aaa;
+}
+th > a {
+  text-decoration:none;
+}