<div id="countdown" style="font-size:20px; font-weight:bold;"></div>

<script>
// 目標日時（日本時間）
const targetTime = new Date("2025-12-13T13:05:00+09:00");

function updateCountdown() {
const now = new Date();
const diff = targetTime - now;
const el = document.getElementById("countdown");

if (diff <= 0) {
el.textContent = "カウントダウン終了！";
clearInterval(timerId);
return;
}

const days = Math.floor(diff / (1000 * 60 * 60 * 24));
const hours = Math.floor((diff / (1000 * 60 * 60)) % 24);
const mins = Math.floor((diff / (1000 * 60)) % 60);
const secs = Math.floor((diff / 1000) % 60);

el.textContent =
"試合開始まで " +
days + "日 " +
hours.toString().padStart(2, "0") + "時間 " +
mins.toString().padStart(2, "0") + "分 " +
secs.toString().padStart(2, "0") + "秒";
}

const timerId = setInterval(updateCountdown, 1000);
updateCountdown();
</script>