diff --git a/script/main.js b/script/main.js
index 1be7269..69dc4b8 100644
--- a/script/main.js
+++ b/script/main.js
@@ -1,17 +1,35 @@
 const button = document.getElementById("theme");
 const classes = document.documentElement.classList;
 
-function refresh() {
-    button.innerHTML = theme();
+function button_refresh() {
+    button.innerHTML = theme_get();
 }
-
-function theme() {
+function theme_get() {
     return classes.contains("dark")?"dark":"light";
 }
+function theme_read() {
+    const theme = localStorage.getItem("theme");
+    if (theme) {
+        theme_set(theme);
+    }
+}
+function theme_set(theme) {
+    if (theme == "dark") {
+        classes.add("dark");
+    }
+    button_refresh();
+}
+function theme_toggle() {
+    classes.toggle("dark");
+    button_refresh();
+    theme_write();
+}
+function theme_write() {
+    localStorage.setItem("theme", theme_get());
+}
 
 button.addEventListener("click", () => {
-    classes.toggle("dark");
-    refresh();
+    theme_toggle();
 });
 
-refresh();
+theme_read();