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

body {
    min-height: 100vh;
    display: flex;
    justify-content: center;
    /* căn giữa ngang */
    align-items: center;
    /* căn giữa dọc */
    background: url("background.gif") no-repeat center center fixed;
    background-size: cover;
    font-family: "Segoe UI", Tahoma, sans-serif;
    overflow: hidden;
    padding-top: 0;
    /* bỏ padding-top để không đẩy card lệch */
}

.snowflake {
    position: fixed;
    top: -10px;
    color: #fff;
    font-size: 1.2rem;
    animation: fall linear infinite;
    pointer-events: none;
}

@keyframes fall {
    0% {
        transform: translateY(0);
        opacity: 1;
    }
    100% {
        transform: translateY(100vh);
        opacity: 0.8;
    }
}

.card {
    backdrop-filter: blur(20px);
    background: rgba(255, 255, 255, 0.18);
    border: 3px solid rgba(255, 255, 255, 0.6);
    border-radius: 26px;
    padding: 40px 35px;
    text-align: center;
    width: 90%;
    max-width: 420px;
    box-shadow: 0 8px 35px rgba(0, 0, 0, 0.18);
    animation: fadeIn 1s ease forwards;
    transition: transform 0.35s ease, box-shadow 0.35s ease, border-color 0.35s ease;
    position: relative;
    z-index: 1;
}

.card:hover {
    transform: translateY(20%) scale(1.05);
    border-color: rgb(0, 255, 255);
    /* đổi viền sang xanh ngọc khi hover */
    box-shadow: 0 0 25px rgba(0, 255, 255, 0.8);
    /* phát sáng viền */
}

.btn-container {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.contact-btn {
    position: relative;
    overflow: hidden;
    border: none;
    border-radius: 16px;
    padding: 16px 20px;
    font-size: 1rem;
    color: #fff;
    background: #222;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    font-weight: 600;
    opacity: 0;
    animation: fadeUp 0.8s forwards;
    transition: transform 0.25s ease, filter 0.25s ease, box-shadow 0.25s ease;
}

.contact-btn i {
    font-size: 1.2rem;
}

.contact-btn:hover {
    transform: translateY(-4px) scale(1.05);
    filter: brightness(1.1);
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.25);
}

.contact-btn::after {
    content: "";
    position: absolute;
    top: 0;
    left: -75%;
    width: 50%;
    height: 100%;
    background: rgba(255, 255, 255, 0.35);
    transform: skewX(-20deg);
    transition: 0.5s;
}

.contact-btn:hover::after {
    left: 130%;
}

.facebook:hover {
    background: #1877f2;
    color: #fff;
    box-shadow: 0 4px 10px rgba(24, 119, 242, 0.4);
}

.tiktok:hover {
    background: #010101;
    color: #fff;
    box-shadow: 0 4px 10px rgba(1, 1, 1, 0.4);
}

.zalo:hover {
    background: #0068ff;
    color: #fff;
    box-shadow: 0 4px 10px rgba(0, 104, 255, 0.4);
}

.telegram:hover {
    background: #229ed9;
    color: #fff;
    box-shadow: 0 4px 10px rgba(34, 158, 217, 0.4);
}

.github:hover {
    background: #181717;
    color: #fff;
    box-shadow: 0 4px 10px rgba(24, 23, 23, 0.4);
}

.contact-btn:nth-child(1) {
    animation-delay: 0.2s;
}

.contact-btn:nth-child(2) {
    animation-delay: 0.4s;
}

.contact-btn:nth-child(3) {
    animation-delay: 0.6s;
}

.contact-btn:nth-child(4) {
    animation-delay: 0.8s;
}

.contact-btn:nth-child(5) {
    animation-delay: 1s;
}

#musicBtn {
    position: fixed;
    bottom: 25px;
    right: 25px;
    width: 50px;
    height: 50px;
    border: none;
    border-radius: 50%;
    background: rgba(34, 34, 34, 0.85);
    color: #fff;
    font-size: 1.3rem;
    cursor: pointer;
    backdrop-filter: blur(12px);
    box-shadow: 0 6px 22px rgba(0, 0, 0, 0.3);
    transition: transform 0.3s ease, background 0.3s ease, box-shadow 0.3s ease;
    opacity: 0;
    animation: fadeIn 1s forwards;
    animation-delay: 1s;
}

#musicBtn:hover {
    background: #555;
    transform: scale(1.12) rotate(10deg);
    box-shadow: 0 8px 28px rgba(0, 0, 0, 0.35);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(0.95);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes fadeUp {
    from {
        opacity: 0;
        transform: translateY(25px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 450px) {
    .card {
        padding: 30px 20px;
    }
    .contact-btn {
        font-size: 0.95rem;
    }
}

.tilted-card-figure {
    position: relative;
    width: 100%;
    height: 100%;
    perspective: 800px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.tilted-card-mobile-alert {
    position: absolute;
    top: 1rem;
    text-align: center;
    font-size: 0.875rem;
    display: none;
}

@media (max-width: 640px) {
    .tilted-card-mobile-alert {
        display: block;
    }
    .tilted-card-caption {
        display: none;
    }
}

.tilted-card-inner {
    position: relative;
    transform-style: preserve-3d;
}

.tilted-card-img {
    position: absolute;
    top: 0;
    left: 0;
    object-fit: cover;
    border-radius: 15px;
    will-change: transform;
    transform: translateZ(0);
}

.tilted-card-overlay {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 2;
    will-change: transform;
    transform: translateZ(30px);
}

.tilted-card-caption {
    pointer-events: none;
    position: absolute;
    left: 0;
    top: 0;
    border-radius: 4px;
    background-color: #fff;
    padding: 4px 10px;
    font-size: 10px;
    color: #2d2d2d;
    opacity: 0;
    z-index: 3;
}

.gif-img {
    width: 120px;
    height: 120px;
    margin: 15px 0;
    border-radius: 50%;
    border: 4px solid rgb(255, 255, 255);
    /* viền trắng */
    object-fit: cover;
    box-shadow: 0 0 15px rgba(255, 255, 255, 0.6);
    /* ánh sáng nhẹ */
    transition: border-color 0.4s ease, box-shadow 0.4s ease;
}

.gif-img:hover {
    border-color: rgb(0, 255, 255);
    /* đổi sang xanh ngọc khi hover */
    box-shadow: 0 0 25px rgba(0, 255, 255, 0.8);
    /* phát sáng mạnh hơn */
}

.slider-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    width: 12rem;
}

.slider-wrapper {
    display: flex;
    width: 100%;
    touch-action: none;
    user-select: none;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.slider-root {
    position: relative;
    display: flex;
    width: 100%;
    max-width: 200px;
    flex-grow: 1;
    cursor: grab;
    touch-action: none;
    user-select: none;
    align-items: center;
    padding: 1rem 0;
}

.slider-root:active {
    cursor: grabbing;
}

.slider-track-wrapper {
    display: flex;
    flex-grow: 1;
}

.slider-track {
    position: relative;
    height: 100%;
    flex-grow: 1;
    overflow: hidden;
    border-radius: 9999px;
    background-color: rgba(128, 128, 128, 0.4);
}

.slider-range {
    position: absolute;
    height: 100%;
    background-color: #888;
    border-radius: 9999px;
}

.value-indicator {
    color: #808080;
    position: absolute;
    transform: translateY(-1rem);
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.05em;
}

.icon {
    width: 24px;
    height: 24px;
    color: #888;
}

.icon.dark {
    color: #ddd;
}

.slider-thumb {
    position: absolute;
    width: 1.5rem;
    height: 1.5rem;
    background-color: #fff;
    border-radius: 50%;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
}

.ribbons-container {
    width: 100%;
    height: 100%;
    position: relative;
}

.icon-img {
    width: 20px;
    /* kích thước icon */
    height: 20px;
    object-fit: contain;
}