diff --git a/app.js b/app.js
new file mode 100644
index 0000000..2fb1c4f
--- /dev/null
+++ b/app.js
@@ -0,0 +1,23 @@
+function loadPage(section, page) {
+    let buttons = document.getElementById(section).getElementsByTagName("button");
+    let currSel;
+    for (let i in buttons) {
+        if (buttons[i].classList?.contains("sel-btn")) {
+            if (page - 1 == i) return;
+            else {
+                currSel = buttons[i];
+                break;
+            }
+        }
+    }
+
+    fetch(section + "_page" + page + ".html")
+        .then((response) => response.text())
+        .then((data) => {
+            document.getElementById(section + "-content").innerHTML = data;
+            if (currSel) {
+                currSel.classList.remove("sel-btn");
+            }
+            document.getElementById(section).getElementsByTagName("button")[page - 1].classList.add("sel-btn");
+        });
+}
diff --git a/build.sh b/build.sh
index 8fdee57..22ffdf1 100755
--- a/build.sh
+++ b/build.sh
@@ -26,36 +26,10 @@ write_header(){
 
 <head>
   <meta charset=\"utf-8\">
-  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <meta name='viewport' content='idth=device-width, initial-scale=1.0'>
   <link rel=\"stylesheet\" type=\"text/css\" href=\"style.css\">
   <title>Gruvbox wallpapers</title>
-  <script>
-    function loadPage(section, page) {
-      let buttons = document.getElementById(section ).getElementsByTagName('button');
-      let currSel;
-      for(let i in buttons){
-        if(buttons[i].classList?.contains('sel-btn')){
-          if(page-1 == i)
-            return;
-          else{
-            currSel = buttons[i];
-            break;
-          }
-        }
-
-      }
-
-      fetch(section + '_page' + page + '.html')
-        .then(response => response.text())
-        .then(data => {
-          document.getElementById(section + '-content').innerHTML = data;
-          if (currSel){
-            currSel.classList.remove('sel-btn');
-          }
-          document.getElementById(section).getElementsByTagName('button')[page-1].classList.add('sel-btn');
-        });
-    }
-  </script>
+  <script src='app.js' defer></script>
 </head>
 
 <body>
