add darkmode support

Author: vapier

lib/core/show-dir/styles.js

@@ -9,6 +9,17 @@ css += 'table tr { white-space: nowrap; }\n';
 css += 'td.perms {}\n';
 css += 'td.file-size { text-align: right; padding-left: 1em; }\n';
 css += 'td.display-name { padding-left: 1em; }\n';
+css += `
+@media (prefers-color-scheme: dark) {
+  body {
+    background-color: #303030;
+    color: #efefef;
+  }
+  a {
+    color: #ffff11;
+  }
+}
+`;
 
 Object.keys(icons).forEach((key) => {
   css += `i.icon-${key} {\n`;