diff --git a/change.js b/change.js
new file mode 100644
index 0000000..f17798a
--- /dev/null
+++ b/change.js
@@ -0,0 +1,55 @@
+document.addEventListener("DOMContentLoaded", () => {
+    var head = document.querySelector("head");
+    var newcss;
+    let cssbtn1 = document.getElementById("css1");
+    let cssbtn2 = document.getElementById("css2");
+    let cssbtn3 = document.getElementById("css3");
+    
+    //function bg1(){
+    cssbtn1.addEventListener("click", (e) => {  
+	if (newcss) return;
+	newcss = document.createElement("link");
+	newcss.rel = "stylesheet";
+	newcss.href = "new1.css";
+	head.appendChild(newcss);	// link要素を追加
+    });
+    /*if(bg2 && bg3){
+            newcss.remove();
+            newcss = null;
+    }*/
+//}
+    //function bg2(){
+    cssbtn2.addEventListener("click", (e) => {  
+        if (newcss) return;
+        newcss = document.createElement("link");
+        newcss.rel = "stylesheet";
+        newcss.href = "new2.css";
+        head.appendChild(newcss);	// link要素を追加
+        });
+        /*if(bg1 && bg3){
+                newcss.remove();
+                newcss = null;
+        }*/
+    //}
+    //function bg3(){
+    cssbtn3.addEventListener("click", (e) => {  
+            if (newcss) return;
+            newcss = document.createElement("link");
+            newcss.rel = "stylesheet";
+            // ※newcss.title = "あとから版";	// title属性入れると代替CSSに
+            newcss.href = "new3.css";
+            head.appendChild(newcss);	// link要素を追加
+            });
+            /*if(bg2 && bg1){
+                    newcss.remove();
+                    newcss = null;
+            }*/
+        //}
+        let unlbtn = document.getElementById("unl");
+        unlbtn.addEventListener("click", (e) => {
+            if (newcss) {
+                newcss.remove();
+                newcss = null;
+            }
+        }); 
+});