refactor: replace css fade animations with gsap, optimize post page animations and mobile responsiveness

src/components/Widgets/BackButton.astro

@@ -0,0 +1,29 @@
+---
+import GoBackIcon from '@/assets/icons/go-back.svg';
+---
+
+<button
+  id="back-button"
+  class="hidden"
+  lg="block absolute c-secondary/40 left--10 top-1/2 aspect-square w-4.5 translate-y--1/2 transition-colors duration-300 ease-out c-secondary active:scale-90 hover:c-primary/80"
+  aria-label="Go back"
+>
+  <GoBackIcon
+    aria-hidden="true"
+    fill="currentColor"
+  />
+</button>
+
+<!-- Go Back Script >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> -->
+<script>
+function setupBackButton() {
+  document.getElementById('back-button')?.addEventListener('click', () => {
+    if (window.history.length > 1) {
+      window.history.back()
+    }
+  })
+}
+
+setupBackButton()
+document.addEventListener('astro:after-swap', setupBackButton)
+</script>