@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;700;900&display=swap');

:root {
    --primary-color: #ffffff;
    --secondary-color: #e0e0e0;
    --accent-color: #ff9800;
    --background-start: #1a0c3b;
    --background-end: #3b1c5f;
    --shadow-color: rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: 'Roboto', sans-serif;
    color: var(--primary-color);
    background: linear-gradient(-45deg, var(--background-start), var(--background-end), #23a6d5, #23d5ab);
    background-size: 400% 400%;
    animation: gradientBG 15s ease infinite;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    text-align: center;
    overflow: hidden;
    position: relative;
}

@keyframes gradientBG {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

.overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://www.transparenttextures.com/patterns/cubes.png'); /* Họa tiết khối lập phương tinh tế */
    opacity: 0.05;
}

.container {
    position: relative;
    z-index: 1;
    padding: 2rem;
    background: rgba(0, 0, 0, 0.25);
    border-radius: 20px;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 8px 32px 0 var(--shadow-color);
    max-width: 90%;
    width: 700px;
}

.header {
    margin-bottom: 2.5rem;
}

.main-title {
    font-size: 3.5rem;
    font-weight: 900;
    text-transform: uppercase;
    letter-spacing: 2px;
    text-shadow: 0 0 10px var(--accent-color), 0 0 20px var(--accent-color);
}

.subtitle {
    font-size: 1.5rem;
    font-weight: 400;
    color: var(--secondary-color);
    margin-top: 0.5rem;
}

.countdown-container {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.countdown-item {
    display: flex;
    flex-direction: column;
}

.countdown-number {
    font-size: 4rem;
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1;
    background: var(--accent-color);
    padding: 1rem;
    border-radius: 10px;
    min-width: 100px;
    text-shadow: 2px 2px 4px var(--shadow-color);
}

.countdown-label {
    font-size: 1rem;
    color: var(--secondary-color);
    margin-top: 0.75rem;
    text-transform: uppercase;
}

.contact p {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--secondary-color);
}

.social-icons a {
    color: var(--primary-color);
    font-size: 2rem;
    margin: 0 1rem;
    transition: color 0.3s ease, transform 0.3s ease;
}

.social-icons a:hover {
    color: var(--accent-color);
    transform: scale(1.2);
}

/* Responsive Design */
@media (max-width: 768px) {
    .main-title {
        font-size: 2.5rem;
    }
    .subtitle {
        font-size: 1.2rem;
    }
    .countdown-container {
        gap: 1rem;
    }
    .countdown-number {
        font-size: 2rem;
        padding: 0.8rem;
        min-width: 70px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 1.5rem;
    }
    .main-title {
        font-size: 2rem;
    }
    .countdown-container {
        flex-wrap: wrap;
        gap: 1.5rem;
    }
    .countdown-item {
        flex-basis: 40%;
    }
    .countdown-number {
        font-size: 2.5rem;
    }
}