moved js to its own static file

static/js/script.js

@@ -0,0 +1,21 @@
+const setTheme = (theme) => {
+  document.documentElement.className = theme;
+  localStorage.setItem('theme', theme);
+}
+
+const hasCodeRun = localStorage.getItem('hasCodeRun');
+
+if (!hasCodeRun) {
+  const defaultTheme = "{{ config.extra.default_theme }}";
+  setTheme(defaultTheme);
+  localStorage.setItem('hasCodeRun', 'true');
+}
+
+const getTheme = () => {
+  const theme = localStorage.getItem('theme');
+  if (theme) {
+    setTheme(theme);
+  }
+}
+
+getTheme();