/* ---- CSS CHO TRANG TẾT ---- */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Arial', sans-serif;
    overflow: hidden;
    height: 100vh;
    background-image: linear-gradient(
        rgba(0, 0, 0, 0.3),
        rgba(20, 20, 20, 0.6)
    ), url('images/tet.png');
    background-size: cover, cover;
    background-position: center, center;
    background-repeat: no-repeat, no-repeat;
}

.back-btn {
    position: fixed;
    top: 20px;
    left: 20px;
    z-index: 1000;
    background: linear-gradient(135deg, #2196F3, #1976D2);
    color: white;
    border: none;
    border-radius: 50px;
    padding: 12px 20px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    box-shadow: 
        0 4px 15px rgba(33, 150, 243, 0.4),
        0 0 20px rgba(33, 150, 243, 0.3);
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.back-btn:hover {
    transform: translateY(-2px);
    box-shadow: 
        0 6px 20px rgba(33, 150, 243, 0.6),
        0 0 30px rgba(33, 150, 243, 0.5);
    background: linear-gradient(135deg, #42A5F5, #2196F3);
}

.tet-screen {
    width: 100vw;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    z-index: 1;
}

.tet-content {
    text-align: center;
    color: white;
    position: relative;
    background: rgba(0, 0, 0, 0.7);
    padding: 50px;
    border-radius: 25px;
    backdrop-filter: blur(15px);
    border: 3px solid rgba(255, 215, 0, 0.4);
    box-shadow: 
        0 0 60px rgba(255, 215, 0, 0.4),
        inset 0 0 30px rgba(255, 215, 0, 0.1);
    max-width: 90vw;
    max-height: 90vh;
    overflow-y: auto;
    animation: fadeInScale 1s ease-out;
}

@keyframes fadeInScale {
    from {
        opacity: 0;
        transform: scale(0.8);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.tet-title {
    font-size: 3rem;
    margin-bottom: 40px;
    background: linear-gradient(45deg, #ffd700, #ffed4a, #ff6b6b);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 0 30px rgba(255, 215, 0, 0.6);
    font-weight: bold;
    animation: titleGlow 2s ease-in-out infinite alternate;
}

@keyframes titleGlow {
    from {
        text-shadow: 0 0 30px rgba(255, 215, 0, 0.6);
    }
    to {
        text-shadow: 0 0 50px rgba(255, 215, 0, 0.9);
    }
}

.countdown-container {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin: 50px 0;
    flex-wrap: wrap;
}

.countdown-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    background: rgba(255, 255, 255, 0.15);
    padding: 25px 20px;
    border-radius: 20px;
    border: 2px solid rgba(255, 215, 0, 0.4);
    min-width: 100px;
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        box-shadow: 0 0 20px rgba(255, 215, 0, 0.3);
    }
    50% {
        transform: scale(1.05);
        box-shadow: 0 0 30px rgba(255, 215, 0, 0.5);
    }
}

.countdown-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(255, 215, 0, 0.6);
}

.countdown-number {
    font-size: 3.5rem;
    font-weight: bold;
    color: #ffd700;
    text-shadow: 0 0 15px rgba(255, 215, 0, 0.9);
    font-family: 'Courier New', monospace;
    line-height: 1;
    animation: numberGlow 1s ease-in-out infinite alternate;
}

@keyframes numberGlow {
    from {
        text-shadow: 0 0 15px rgba(255, 215, 0, 0.9);
    }
    to {
        text-shadow: 0 0 25px rgba(255, 215, 0, 1);
    }
}

.countdown-label {
    font-size: 1.2rem;
    color: #fff;
    margin-top: 8px;
    opacity: 0.9;
    font-weight: 600;
    text-shadow: 0 0 10px rgba(255, 255, 255, 0.5);
}

.tet-message {
    margin-top: 40px;
}

.tet-message p {
    font-size: 1.5rem;
    color: #fff;
    opacity: 0.9;
    font-style: italic;
    text-shadow: 0 0 15px rgba(255, 255, 255, 0.6);
}

/* ---- HIỆU ỨNG TRANG TRÍ TẾT ---- */
.tet-decorations {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    pointer-events: none;
    overflow: hidden;
    z-index: 0;
}

/* Pháo hoa */
.firework {
    position: absolute;
    width: 4px;
    height: 4px;
    border-radius: 50%;
    animation: fireworkBurst 3s ease-out infinite;
}

.firework-1 {
    background: #ff6b6b;
    top: 10%;
    left: 20%;
    animation-delay: 0s;
}

.firework-2 {
    background: #4ecdc4;
    top: 20%;
    right: 20%;
    animation-delay: 1s;
}

.firework-3 {
    background: #ffe66d;
    bottom: 30%;
    left: 30%;
    animation-delay: 2s;
}

@keyframes fireworkBurst {
    0% {
        transform: scale(0);
        opacity: 1;
        box-shadow: 
            0 0 0 0 currentColor,
            0 0 0 0 currentColor,
            0 0 0 0 currentColor,
            0 0 0 0 currentColor;
    }
    50% {
        transform: scale(1);
        opacity: 1;
        box-shadow: 
            30px 0 0 -2px currentColor,
            -30px 0 0 -2px currentColor,
            0 30px 0 -2px currentColor,
            0 -30px 0 -2px currentColor,
            21px 21px 0 -2px currentColor,
            -21px -21px 0 -2px currentColor,
            21px -21px 0 -2px currentColor,
            -21px 21px 0 -2px currentColor;
    }
    100% {
        transform: scale(1);
        opacity: 0;
        box-shadow: 
            50px 0 0 -4px currentColor,
            -50px 0 0 -4px currentColor,
            0 50px 0 -4px currentColor,
            0 -50px 0 -4px currentColor,
            35px 35px 0 -4px currentColor,
            -35px -35px 0 -4px currentColor,
            35px -35px 0 -4px currentColor,
            -35px 35px 0 -4px currentColor;
    }
}

/* Đèn lồng */
.lantern {
    position: absolute;
    font-size: 3rem;
    animation: swing 3s ease-in-out infinite;
}

.lantern-left {
    top: 5%;
    left: 5%;
    animation-delay: 0s;
}

.lantern-right {
    top: 5%;
    right: 5%;
    animation-delay: 1.5s;
}

@keyframes swing {
    0%, 100% {
        transform: rotate(-10deg);
    }
    50% {
        transform: rotate(10deg);
    }
}

/* Cánh hoa rơi */
.flower-petals {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.petal {
    position: absolute;
    top: -10%;
    font-size: 2rem;
    opacity: 0.7;
    animation: petalFall 8s linear infinite;
}

.petal-1 {
    left: 10%;
    animation-delay: 0s;
    animation-duration: 7s;
}

.petal-2 {
    left: 30%;
    animation-delay: 2s;
    animation-duration: 9s;
}

.petal-3 {
    left: 50%;
    animation-delay: 4s;
    animation-duration: 6s;
}

.petal-4 {
    left: 70%;
    animation-delay: 6s;
    animation-duration: 8s;
}

.petal-5 {
    left: 88%;
    animation-delay: 1s;
    animation-duration: 10s;
}

@keyframes petalFall {
    0% {
        top: -10%;
        transform: translateX(0px) rotate(0deg);
        opacity: 0.8;
    }
    25% {
        transform: translateX(40px) rotate(90deg);
    }
    50% {
        transform: translateX(-20px) rotate(180deg);
    }
    75% {
        transform: translateX(30px) rotate(270deg);
    }
    100% {
        top: 105%;
        transform: translateX(0px) rotate(360deg);
        opacity: 0.3;
    }
}

/* ---- RESPONSIVE ---- */
@media (max-width: 768px) {
    .tet-title {
        font-size: 2.2rem;
    }
    
    .countdown-number {
        font-size: 2.5rem;
    }
    
    .countdown-container {
        gap: 15px;
    }
    
    .countdown-item {
        padding: 20px 15px;
        min-width: 80px;
    }
    
    .tet-content {
        padding: 40px 30px;
    }
    
    .countdown-label {
        font-size: 1rem;
    }
    
    .tet-message p {
        font-size: 1.2rem;
    }
}

@media (max-width: 480px) {
    .back-btn {
        top: 10px;
        left: 10px;
        padding: 10px 16px;
        font-size: 14px;
    }
    
    .tet-title {
        font-size: 1.8rem;
        margin-bottom: 30px;
    }
    
    .countdown-number {
        font-size: 2rem;
    }
    
    .countdown-label {
        font-size: 0.9rem;
    }
    
    .countdown-container {
        gap: 10px;
        margin: 30px 0;
    }
    
    .countdown-item {
        padding: 15px 10px;
        min-width: 70px;
    }
    
    .tet-content {
        padding: 30px 20px;
    }
    
    .tet-message p {
        font-size: 1rem;
    }
    
    .lantern {
        font-size: 2rem;
    }
    
    .petal {
        font-size: 1.5rem;
    }
}