Add @number-flow/react dependency and integrate SiteTopBanner component into layout

src/app/layout.tsx

@@ -3,6 +3,7 @@ import { Cal_Sans, Geist_Mono, Bricolage_Grotesque } from "next/font/google";
 import localFont from "next/font/local";
 import { Toaster } from "@/components/ui/sonner";
 import { SiteHeader } from "@/components/site-header";
+import { SiteTopBanner } from "@/components/site-top-banner";
 import { ListeCekmecesi } from "@/components/manuel-liste/liste-cekmecesi";
 import { HeaderGate } from "@/components/header-gate";
 import { ProgressiveBlur } from "@/components/ui/skiper-ui/skiper41";
@@ -73,6 +74,7 @@ export default function RootLayout({
           />
         </div>
         <HeaderGate>
+          <SiteTopBanner />
           <SiteHeader />
         </HeaderGate>
         <ScrollFlow className="flex min-h-0 flex-1 flex-col">

src/components/site-top-banner.tsx

@@ -0,0 +1,141 @@
+"use client";
+
+import { useEffect, useState } from "react";
+import NumberFlow, { NumberFlowGroup } from "@number-flow/react";
+import { CalendarDays, Clock3 } from "lucide-react";
+
+const TERCIH_BASLANGICI = new Date("2026-07-29T00:00:00+03:00").getTime();
+const TERCIH_BITISI = new Date("2026-08-10T23:59:59+03:00").getTime();
+
+type GeriSayim = {
+  asama: "baslamadi" | "devam-ediyor" | "sona-erdi";
+  gun: number;
+  saat: number;
+  dakika: number;
+  saniye: number;
+};
+
+function geriSayimiHesapla(simdi: number): GeriSayim {
+  const asama =
+    simdi < TERCIH_BASLANGICI
+      ? "baslamadi"
+      : simdi <= TERCIH_BITISI
+        ? "devam-ediyor"
+        : "sona-erdi";
+
+  const hedef =
+    asama === "baslamadi" ? TERCIH_BASLANGICI : TERCIH_BITISI;
+  const kalan = Math.max(0, hedef - simdi);
+
+  return {
+    asama,
+    gun: Math.floor(kalan / 86_400_000),
+    saat: Math.floor((kalan % 86_400_000) / 3_600_000),
+    dakika: Math.floor((kalan % 3_600_000) / 60_000),
+    saniye: Math.floor((kalan % 60_000) / 1_000),
+  };
+}
+
+const BIRIMLER = [
+  { anahtar: "gun", etiket: "gün" },
+  { anahtar: "saat", etiket: "sa" },
+  { anahtar: "dakika", etiket: "dk" },
+  { anahtar: "saniye", etiket: "sn" },
+] as const;
+
+export function SiteTopBanner() {
+  const [geriSayim, setGeriSayim] = useState<GeriSayim | null>(null);
+
+  useEffect(() => {
+    const guncelle = () => setGeriSayim(geriSayimiHesapla(Date.now()));
+
+    guncelle();
+    const zamanlayici = window.setInterval(guncelle, 1_000);
+
+    return () => window.clearInterval(zamanlayici);
+  }, []);
+
+  const asamaMetni =
+    geriSayim?.asama === "baslamadi"
+      ? "Başlamasına"
+      : geriSayim?.asama === "sona-erdi"
+        ? "Tercih dönemi sona erdi"
+        : "Sona ermesine";
+
+  return (
+    <section
+      aria-label="2026 YKS tercih dönemi"
+      className="relative z-50 border-b border-primary-foreground/15 bg-primary text-primary-foreground print:hidden"
+    >
+      <div className="mx-auto flex min-h-12 max-w-6xl flex-wrap items-center justify-center gap-x-5 gap-y-1.5 px-4 py-2 sm:justify-between">
+        <div className="flex min-w-0 items-center gap-2.5">
+          <CalendarDays className="size-4 shrink-0 opacity-80" aria-hidden />
+          <p className="truncate text-sm font-semibold tracking-[-0.01em]">
+            <span className="hidden sm:inline">2026 YKS tercih dönemi · </span>
+            <time dateTime="2026-07-29">29 Temmuz</time>
+            <span aria-hidden> – </span>
+            <time dateTime="2026-08-10">10 Ağustos 2026</time>
+          </p>
+        </div>
+
+        <div className="flex items-center gap-2.5" role="timer">
+          <div className="flex items-center gap-1.5 text-xs font-medium opacity-85">
+            <Clock3 className="size-3.5" aria-hidden />
+            <span>{asamaMetni}</span>
+          </div>
+
+          {geriSayim?.asama !== "sona-erdi" ? (
+            <dl
+              className="flex items-baseline gap-1 font-mono text-xs tabular-nums"
+              aria-label={
+                geriSayim
+                  ? `${geriSayim.gun} gün, ${geriSayim.saat} saat, ${geriSayim.dakika} dakika, ${geriSayim.saniye} saniye`
+                  : "Geri sayım yükleniyor"
+              }
+            >
+              <NumberFlowGroup>
+                {BIRIMLER.map(({ anahtar, etiket }) => (
+                  <div className="flex items-baseline gap-0.5" key={anahtar}>
+                    <dt className="sr-only">{etiket}</dt>
+                    <dd className="font-semibold">
+                      {geriSayim ? (
+                        <NumberFlow
+                          value={geriSayim[anahtar]}
+                          trend={-1}
+                          format={{
+                            minimumIntegerDigits: 2,
+                            useGrouping: false,
+                          }}
+                          transformTiming={{
+                            duration: 280,
+                            easing: "cubic-bezier(0.23, 1, 0.32, 1)",
+                          }}
+                          spinTiming={{
+                            duration: 280,
+                            easing: "cubic-bezier(0.23, 1, 0.32, 1)",
+                          }}
+                          opacityTiming={{
+                            duration: 180,
+                            easing: "ease-out",
+                          }}
+                          willChange={anahtar === "saniye"}
+                          className="inline-block min-w-[2ch] text-right"
+                          aria-hidden
+                        />
+                      ) : (
+                        "--"
+                      )}
+                      <span className="ml-0.5 text-[10px] font-medium opacity-70">
+                        {etiket}
+                      </span>
+                    </dd>
+                  </div>
+                ))}
+              </NumberFlowGroup>
+            </dl>
+          ) : null}
+        </div>
+      </div>
+    </section>
+  );
+}