/* Reset và base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-color: #004D00;
    color: #FFFFFF;
    font-family: 'Borel', cursive, sans-serif;
    text-align: center;
    min-height: 100vh;
    overflow: hidden;
    position: relative;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* Lớp tuyết */
#snow-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

.snowflake {
    position: absolute;
    top: -10px;
    background-color: white;
    border-radius: 50%;
    opacity: 0.8;
    animation: fall linear forwards;
}

@keyframes fall {
    to {
        transform: translateY(105vh) translateX(5vw);
        opacity: 0;
    }
}

/* Nội dung chính */
main {
    position: relative;
    z-index: 10;
    width: 100%;
    max-width: 1000px;
    padding: 20px;
    animation: fadeIn 1.5s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

.christmas-title {
    color: #FFD700;
    margin: 0;
    animation: blink 1.5s infinite alternate;
}

.christmas-title.star {
    font-size: 3rem;
    margin: 10px 0;
}

@keyframes blink {
    from { text-shadow: 0 0 5px #FFD700, 0 0 10px #FFD700; }
    to { text-shadow: 0 0 15px #FFD700, 0 0 25px #FFD700; }
}

.countdown-text {
    font-size: 1.2rem;
    margin: 15px 0;
    opacity: 0.9;
}

/* Đồng hồ đếm ngược */
#countdown {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 25px;
    flex-wrap: wrap;
}

.time-block {
    background: rgba(179, 0, 0, 0.8);
    padding: 15px 10px;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
    min-width: 80px;
    backdrop-filter: blur(2px);
    transition: transform 0.2s;
}

.time-block:hover {
    transform: scale(1.05);
}

.time-block span:first-child {
    font-size: 2.5rem;
    font-weight: bold;
    display: block;
}

.time-block span:last-child {
    font-size: 0.9rem;
    text-transform: uppercase;
    margin-top: 5px;
    letter-spacing: 1px;
    opacity: 0.9;
}

/* ==================================== */
/* RESPONSIVE DESIGN */
/* ==================================== */

/* Màn hình lớn (mặc định) */
@media (min-width: 769px) {
    .christmas-title {
        font-size: 2.5rem;
    }
    .christmas-title.star {
        font-size: 4rem;
    }
    .countdown-text {
        font-size: 1.5rem;
    }
    .time-block {
        padding: 20px;
        min-width: 100px;
    }
    .time-block span:first-child {
        font-size: 3rem;
    }
    .time-block span:last-child {
        font-size: 1rem;
    }
}

/* Tablet & Mobile lớn (≤768px) */
@media (max-width: 768px) {
    body {
        padding: 15px;
    }
    .christmas-title {
        font-size: 2.8rem;
        line-height: 1.2;
    }
    .christmas-title.star {
        font-size: 3rem;
    }
    .countdown-text {
        font-size: 1.3rem;
    }
    #countdown {
        gap: 12px;
    }
    .time-block {
        padding: 14px 8px;
        min-width: 70px;
    }
    .time-block span:first-child {
        font-size: 2.2rem;
    }
    .time-block span:last-child {
        font-size: 0.85rem;
    }
}

/* Mobile nhỏ (≤480px) */
@media (max-width: 480px) {
    body {
        padding: 10px;
    }
    .christmas-title {
        font-size: 2.2rem;
    }
    .christmas-title.star {
        font-size: 2.5rem;
    }
    .countdown-text {
        font-size: 1.1rem;
    }
    #countdown {
        gap: 8px;
        margin-top: 20px;
    }
    .time-block {
        padding: 12px 6px;
        min-width: 60px;
    }
    .time-block span:first-child {
        font-size: 1.8rem;
    }
    .time-block span:last-child {
        font-size: 0.75rem;
    }
}

/* Siêu nhỏ (≤350px) */
@media (max-width: 350px) {
    .christmas-title {
        font-size: 1.9rem;
    }
    .christmas-title.star {
        font-size: 2.2rem;
    }
    .time-block {
        min-width: 55px;
        padding: 10px 4px;
    }
    .time-block span:first-child {
        font-size: 1.6rem;
    }
}