.countdown-page {
    position: relative;

    min-height: 100vh;
    min-height: 100dvh;

    padding: 12px;

    display: flex;
    justify-content: center;
    align-items: center;
}

.countdown-page::before {
    content: "";

    position: absolute;
    inset: 12px;

    background-color: var(--paper-color);
    border-radius: 24px;
}

.countdown-container {
    position: relative;
    z-index: 1;

    width: 100%;
    text-align: center;
    padding: 20px;
}

.countdown-title {
    font-size: clamp(28px, 8vw, 42px);
    font-weight: normal;

    margin: 0 0 35px;
}

.countdown-display {
    display: flex;
    justify-content: center;
    align-items: baseline;

    gap: 8px;

    color: var(--accent-color);

    transform-origin: center;
}

#remaining-days {
    font-size: clamp(90px, 25vw, 150px);
    font-weight: bold;
    line-height: 1.2;

    font-variant-numeric: tabular-nums;
}

.countdown-unit {
    font-size: 36px;
}

.countdown-divider {
    display: flex;
    justify-content: center;
    align-items: center;

    gap: 15px;
    margin-top: 25px;

    color: var(--accent-color);
}

.divider-line {
    width: 55px;
    height: 1px;

    background-color: var(--accent-color);
}

.divider-heart {
    font-size: 24px;
}

.birthday-date {
    font-size: 28px;
    letter-spacing: 3px;

    margin-top: 25px;
}

.countdown-footer {
    position: absolute;
    z-index: 1;

    bottom: 35px;

    font-size: 18px;
    text-align: center;
}

/* 鼓動アニメーション */

@keyframes heartbeat {
    0% {
        transform: scale(1);
    }

    10% {
        transform: scale(1.12);
    }

    20% {
        transform: scale(1);
    }

    30% {
        transform: scale(1.07);
    }

    45% {
        transform: scale(1);
    }

    100% {
        transform: scale(1);
    }
}

.countdown-display {
    animation: heartbeat 3s ease-in-out infinite;
}

@media (prefers-reduced-motion: reduce) {
    .countdown-display {
        animation: none;
    }
}