fix img src path, add theme toggle button

styleguide/assets/script/styleguide.js

@@ -1,3 +1,27 @@
 document.querySelector('nav > button').addEventListener('click', (e) => {
     document.querySelector('nav').classList.toggle('visible');
-})
+})
+
+function applyTheme(theme){
+    const html = document.querySelector('html')
+    document.cookie = `theme=${theme}; expires=; SameSite=Strict; Secure`
+    html.classList.remove('dark', 'light')
+    html.classList.add(theme)
+}
+
+document.querySelectorAll('.toggleTheme').forEach(
+    element => element.addEventListener('click', (e) => {
+            const newTheme = element.dataset.theme;
+            applyTheme(newTheme);
+        }
+    )
+);
+
+const themeFromCookie = document.cookie
+    .split("; ")
+    .find((row) => row.startsWith("theme="))
+    ?.split("=")[1];
+
+if (themeFromCookie) {
+    applyTheme(themeFromCookie)
+}