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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    overflow-x: hidden;
    background: #0a0a0a;
}

/* Animated Background */
.background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(45deg, 
        #1a1a2e 0%, 
        #16213e 25%, 
        #0f0f23 50%, 
        #1a1a2e 75%, 
        #16213e 100%);
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
    z-index: -3;
}

.particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -2;
    opacity: 0.6;
}

.particle {
    position: absolute;
    background: rgba(255, 69, 0, 0.3);
    border-radius: 50%;
    animation: float 20s infinite linear;
}

.particle:nth-child(odd) {
    background: rgba(255, 20, 147, 0.3);
    animation-duration: 25s;
}

.particle:nth-child(3n) {
    background: rgba(0, 191, 255, 0.3);
    animation-duration: 30s;
}

/* Grid overlay */
.grid-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
    z-index: -1;
    animation: gridMove 20s linear infinite;
}

/* Header - Fixed z-index issue */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    padding: 1.2rem 2rem;
    background: rgba(10, 10, 10, 0.95);
    backdrop-filter: blur(15px);
    border-bottom: 2px solid rgba(255, 69, 0, 0.3);
    z-index: 1000;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 1.8rem;
    font-weight: 900;
    color: #ff4500;
    text-shadow: 0 0 15px rgba(255, 69, 0, 0.6);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    z-index: 1001;
}

.logo:hover {
    transform: scale(1.05);
    transition: transform 0.3s ease;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
    z-index: 1001;
}

.nav-link {
    color: #fff;
    text-decoration: none;
    padding: 0.8rem 1.5rem;
    border: 2px solid transparent;
    border-radius: 25px;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    font-weight: 600;
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
}

.nav-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 69, 0, 0.3), transparent);
    transition: left 0.5s;
}

.nav-link:hover::before {
    left: 100%;
}

.nav-link:hover {
    border-color: #ff4500;
    box-shadow: 0 0 20px rgba(255, 69, 0, 0.4);
    transform: translateY(-2px);
    background: rgba(255, 69, 0, 0.1);
}

/* Main Content - Fixed padding to account for header */
.main-content {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 6rem 2rem 2rem; /* Added top padding for fixed header */
    position: relative;
}

.content-container {
    max-width: 1200px;
    text-align: center;
    z-index: 10;
}

.hero-title {
    font-size: clamp(3rem, 8vw, 7rem);
    font-weight: 900;
    color: #fff;
    margin-bottom: 1.5rem;
    text-shadow: 
        0 0 20px rgba(255, 69, 0, 0.4),
        0 0 40px rgba(255, 69, 0, 0.2),
        0 0 60px rgba(255, 69, 0, 0.1);
    animation: titleGlow 3s ease-in-out infinite alternate;
    line-height: 1.1;
    letter-spacing: -2px;
}

.hero-subtitle {
    font-size: clamp(1.2rem, 3vw, 1.8rem);
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 2rem;
    font-weight: 400;
    letter-spacing: 3px;
    text-transform: uppercase;
}

.hero-description {
    font-size: 1.2rem;
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: 3rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.8;
    font-weight: 300;
}

.cta-buttons {
    display: flex;
    gap: 2rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 4rem;
}

.cta-button {
    padding: 1.2rem 2.5rem;
    font-size: 1.2rem;
    font-weight: 700;
    text-decoration: none;
    border-radius: 50px;
    transition: all 0.4s ease;
    position: relative;
    overflow: hidden;
    min-width: 220px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.cta-primary {
    background: linear-gradient(135deg, #ff4500 0%, #ff6347 50%, #ff1493 100%);
    color: white;
    box-shadow: 0 8px 25px rgba(255, 69, 0, 0.4);
    border: none;
}

.cta-primary::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left 0.6s;
}

.cta-primary:hover::before {
    left: 100%;
}

.cta-primary:hover {
    transform: translateY(-5px) scale(1.05);
    box-shadow: 0 15px 35px rgba(255, 69, 0, 0.6);
}

.cta-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
    border: 2px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
}

.cta-secondary:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: #ff4500;
    transform: translateY(-5px) scale(1.05);
    box-shadow: 0 15px 35px rgba(255, 69, 0, 0.3);
}

/* Features Section */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2.5rem;
    margin-top: 5rem;
}

.feature-card {
    background: rgba(255, 255, 255, 0.08);
    padding: 2.5rem;
    border-radius: 20px;
    border: 1px solid rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(15px);
    transition: all 0.4s ease;
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #ff4500, #ff6347, #ff1493);
    transform: scaleX(0);
    transition: transform 0.4s ease;
}

.feature-card::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    background: radial-gradient(circle, rgba(255, 69, 0, 0.1) 0%, transparent 70%);
    transform: translate(-50%, -50%);
    transition: all 0.6s ease;
    border-radius: 50%;
}

.feature-card:hover::before {
    transform: scaleX(1);
}

.feature-card:hover::after {
    width: 200%;
    height: 200%;
}

.feature-card:hover {
    transform: translateY(-15px) rotateX(5deg);
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.4);
    border-color: rgba(255, 69, 0, 0.4);
}

.feature-icon {
    font-size: 4rem;
    margin-bottom: 1.5rem;
    color: #ff4500;
    text-shadow: 0 0 20px rgba(255, 69, 0, 0.5);
    position: relative;
    z-index: 2;
}

.feature-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 1.5rem;
    position: relative;
    z-index: 2;
}

.feature-text {
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.7;
    font-size: 1.1rem;
    position: relative;
    z-index: 2;
}

/* Stats Section */
.stats {
    display: flex;
    justify-content: center;
    gap: 5rem;
    margin: 5rem 0;
    flex-wrap: wrap;
}

.stat-item {
    text-align: center;
    position: relative;
}

.stat-item::before {
    content: '';
    position: absolute;
    top: -20px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, #ff4500, #ff1493);
    border-radius: 2px;
}

.stat-number {
    font-size: 4rem;
    font-weight: 900;
    color: #ff4500;
    display: block;
    text-shadow: 0 0 20px rgba(255, 69, 0, 0.6);
    margin-top: 1rem;
}

.stat-label {
    color: rgba(255, 255, 255, 0.8);
    font-size: 1.2rem;
    margin-top: 1rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 2px;
}

/* Mobile Responsive */
@media (max-width: 400px) {
    .main-content {
        padding: 9rem 0.5rem 2rem !important;
    }
    .hero-title {
        font-size: 1.5rem !important;
    }
    .cta-button {
        min-width: 110px;
        max-width: 150px;
        font-size: 0.95rem;
        padding: 0.7rem 0.7rem;
    }
}

@media (max-width: 768px) {
    .header {
        padding: 1rem;
    }

    .nav {
        flex-direction: row;
        justify-content: space-between;
    }

    .logo {
        font-size: 1.4rem;
    }

    .nav-links {
        flex-wrap: wrap;
        justify-content: flex-end;
        gap: 0.3rem;
        padding-bottom: 0.2rem;
    }

    .nav-link {
        font-size: 0.8rem;
        padding: 0.4rem 0.5rem;
        min-width: 70px;
        border-radius: 18px;
        margin-bottom: 0.2rem;
    }

    .main-content {
        padding: 7rem 1rem 2rem; /* Tăng padding-top để tránh che chữ */
    }

    .hero-title {
        font-size: 2.2rem;
    }

    .cta-buttons {
        flex-direction: column;
        align-items: center;
        gap: 1.2rem;
    }

    .cta-button {
        width: auto;
        min-width: 140px;
        max-width: 200px;
        padding-left: 1.2rem;
        padding-right: 1.2rem;
        font-size: 1rem;
    }

    .stats {
        gap: 3rem;
    }

    .stat-number {
        font-size: 2.5rem;
    }

    .features {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
}

/* Animations */
@keyframes gradientShift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

@keyframes float {
    0% {
        transform: translateY(100vh) rotate(0deg);
        opacity: 0;
    }
    10% {
        opacity: 1;
    }
    90% {
        opacity: 1;
    }
    100% {
        transform: translateY(-100vh) rotate(360deg);
        opacity: 0;
    }
}

@keyframes gridMove {
    0% { transform: translate(0, 0); }
    100% { transform: translate(50px, 50px); }
}

@keyframes titleGlow {
    0% { 
        text-shadow: 
            0 0 20px rgba(255, 69, 0, 0.4),
            0 0 40px rgba(255, 69, 0, 0.2);
    }
    100% { 
        text-shadow: 
            0 0 30px rgba(255, 69, 0, 0.6), 
            0 0 50px rgba(255, 69, 0, 0.4),
            0 0 70px rgba(255, 69, 0, 0.2);
    }
}

/* Pulse effect for emergency button */
@keyframes pulse {
    0% { 
        box-shadow: 0 8px 25px rgba(255, 69, 0, 0.4);
        transform: scale(1);
    }
    50% { 
        box-shadow: 0 8px 35px rgba(255, 69, 0, 0.8);
        transform: scale(1.02);
    }
    100% { 
        box-shadow: 0 8px 25px rgba(255, 69, 0, 0.4);
        transform: scale(1);
    }
}

.cta-primary {
    animation: pulse 3s infinite;
}

/* Smooth entrance animations */
.hero-title {
    animation: titleGlow 3s ease-in-out infinite alternate, fadeInUp 1s ease-out;
}

.hero-subtitle {
    animation: fadeInUp 1s ease-out 0.3s both;
}

.hero-description {
    animation: fadeInUp 1s ease-out 0.6s both;
}

.cta-buttons {
    animation: fadeInUp 1s ease-out 0.9s both;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}