feat: rewrite to use app config and rework docs (#143)

Co-authored-by: Daniel Roe <daniel@roe.dev>
Co-authored-by: Sébastien Chopin <seb@nuxt.com>

src/runtime/ui.css

@@ -0,0 +1,11 @@
+.dark {
+  color-scheme: dark;
+}
+
+a:focus-visible {
+  @apply outline-primary-500 dark:outline-primary-400;
+}
+
+select {
+  background-image: none;
+}