feat: smooth scrolling

Signed-off-by: ZTL-UwU <[email protected]>

app/router.options.ts

@@ -0,0 +1,38 @@
+import type { RouterConfig } from '@nuxt/schema';
+
+// https://router.vuejs.org/api/interfaces/routeroptions.html
+export default <RouterConfig>{
+  scrollBehavior(to, _form, savedPosition) {
+    return new Promise((resolve) => {
+      setTimeout(() => {
+        if (history.state.smooth) {
+          resolve({
+            el: history.state.smooth,
+            behavior: 'smooth',
+          });
+        }
+
+        if (to.hash) {
+          const el = document.querySelector(to.hash) as any;
+          if (!el)
+            resolve({ el: to.hash, top: 0 });
+
+          const { marginTop } = getComputedStyle(el);
+          const marginTopValue = Number.parseInt(marginTop);
+          const offset = (document.querySelector(to.hash) as any).offsetTop - marginTopValue;
+
+          resolve({
+            top: offset,
+            behavior: 'smooth',
+          });
+        }
+
+        // Scroll to top of window
+        if (savedPosition)
+          resolve(savedPosition);
+        else
+          resolve({ top: 0 });
+      }, 1); // Hack page wise navigation
+    });
+  },
+};