feat(Navbar): custom 800ms ease-in-out smooth scroll via rAF

Replaces browser scroll-behavior:smooth (no duration control) with a
requestAnimationFrame loop using cubic ease-in-out over 800ms. Offset
accounts for navbar height (100px) via getBoundingClientRect + scrollY.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/components/Navbar.tsx

@@ -4,6 +4,28 @@ import { useEffect, useState } from "react";
 import Link from "next/link";
 import Image from "next/image";
 
+const NAVBAR_HEIGHT = 100; // px — matches h-[6.25rem]
+const SCROLL_DURATION = 800; // ms
+
+function smoothScrollTo(targetY: number) {
+  const startY = window.scrollY;
+  const distance = targetY - startY;
+  const startTime = performance.now();
+
+  function step(now: number) {
+    const elapsed = now - startTime;
+    const progress = Math.min(elapsed / SCROLL_DURATION, 1);
+    // ease-in-out cubic
+    const ease = progress < 0.5
+      ? 4 * progress ** 3
+      : 1 - (-2 * progress + 2) ** 3 / 2;
+    window.scrollTo(0, startY + distance * ease);
+    if (progress < 1) requestAnimationFrame(step);
+  }
+
+  requestAnimationFrame(step);
+}
+
 const navLinks = [
   { label: "Werkzeuge", href: "#werkzeuge" },
   { label: "Blog", href: "#blog" },
@@ -50,7 +72,11 @@ export function Navbar() {
                 href={link.href}
                 onClick={(e) => {
                   e.preventDefault();
-                  document.getElementById(link.href.slice(1))?.scrollIntoView({ behavior: "smooth" });
+                  const el = document.getElementById(link.href.slice(1));
+                  if (el) {
+                    const top = el.getBoundingClientRect().top + window.scrollY - NAVBAR_HEIGHT;
+                    smoothScrollTo(top);
+                  }
                   history.replaceState(null, "", link.href);
                 }}
                 className="text-[1.125rem] font-semibold text-[#222221] tracking-[0.01125rem] hover:text-[#f6a701] transition-colors cursor-pointer"

app/globals.css

@@ -13,7 +13,6 @@
 }
 
 html {
-  scroll-behavior: smooth;
   scroll-padding-top: 6.25rem; /* navbar height */
 }