diff --git a/src/js/custom.js b/src/js/custom.js
index 0896cc1..77a78ca 100644
--- a/src/js/custom.js
+++ b/src/js/custom.js
@@ -40,3 +40,53 @@ document.addEventListener("DOMContentLoaded", function () {
         setTimeout(showSlides, 6000);
     }
 });
+
+document.addEventListener('DOMContentLoaded', function() {
+  document.querySelectorAll('.platform-download').forEach(function(block) {
+    const mainBtn = block.querySelector('.big-download-btn, .btnappstore, .btngogoleplay');
+    block.querySelectorAll('.format-option').forEach(function(opt) {
+      opt.addEventListener('click', function() {
+        block.querySelectorAll('.format-option').forEach(o => o.classList.remove('selected'));
+        opt.classList.add('selected');
+        mainBtn.href = opt.dataset.href;
+        mainBtn.textContent = 'Download ' + opt.dataset.label;
+
+        // Special case for macOS App Store
+        if (block.dataset.platform === 'macos') {
+          if (opt.dataset.label === 'App Store') {
+            mainBtn.classList.remove('big-download-btn', 'macos');
+            mainBtn.classList.add('btnappstore');
+            mainBtn.textContent = '';
+          } else {
+            mainBtn.classList.remove('btnappstore');
+            mainBtn.classList.add('big-download-btn', 'macos');
+          }
+        }
+
+        // Special case for Android Play Store
+        if (block.dataset.platform === 'android') {
+          if (opt.dataset.label === 'Play Store') {
+            mainBtn.classList.remove('big-download-btn', 'android');
+            mainBtn.classList.add('btngogoleplay');
+            mainBtn.textContent = '';
+          } else {
+            mainBtn.classList.remove('btngogoleplay');
+            mainBtn.classList.add('big-download-btn', 'android');
+          }
+        }
+
+        // Special case for Linux Flathub
+        if (block.dataset.platform === 'linux') {
+          if (opt.dataset.label === 'FlatHub') {
+            mainBtn.classList.remove('big-download-btn', 'linux');
+            mainBtn.classList.add('btnflathub');
+            mainBtn.textContent = '';
+          } else {
+            mainBtn.classList.remove('btnflathub');
+            mainBtn.classList.add('big-download-btn', 'linux');
+          }
+        }
+      });
+    });
+  });
+});
\ No newline at end of file