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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    max-width: 1200px;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    padding: 40px;
    animation: fadeIn 0.8s ease-in;
}

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

.header {
    text-align: center;
    margin-bottom: 50px;
}

.header h1 {
    font-size: 3rem;
    color: #333;
    margin-bottom: 10px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
}

.brand-name {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    font-size: 3rem;
}

.brand-name i {
    color: #667eea;
    font-size: 2.8rem;
}

.brand-subtitle {
    font-size: 1.8rem;
    color: #666;
    font-weight: 300;
    letter-spacing: 2px;
}

.subtitle {
    font-size: 1.2rem;
    color: #666;
    font-weight: 300;
}

.contact-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}

.contact-card {
    background: white;
    border-radius: 15px;
    padding: 30px;
    text-align: center;
    transition: all 0.3s ease;
    border: 2px solid transparent;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    position: relative;
    overflow: hidden;
}

.contact-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #667eea, #764ba2);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

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

.contact-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.2);
    border-color: #667eea;
}

.contact-card .icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: white;
    transition: all 0.3s ease;
}

.contact-card:hover .icon {
    transform: scale(1.1) rotate(5deg);
}

.contact-card h3 {
    font-size: 1.5rem;
    color: #333;
    margin-bottom: 10px;
}

.contact-card p {
    color: #666;
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.contact-card .btn {
    display: inline-block;
    padding: 12px 25px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-decoration: none;
    border-radius: 25px;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.contact-card .btn:hover {
    transform: scale(1.05);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.6);
}

.contact-card .btn i {
    margin-right: 8px;
}

/* Specific colors for each card */
.contact-card.facebook .icon {
    background: linear-gradient(135deg, #1877f2 0%, #0d5dbf 100%);
}

.contact-card.zalo .icon {
    background: linear-gradient(135deg, #0068ff 0%, #0052cc 100%);
}

.contact-card.hotline .icon {
    background: linear-gradient(135deg, #25d366 0%, #128c7e 100%);
}

.contact-card.telegram .icon {
    background: linear-gradient(135deg, #0088cc 0%, #006699 100%);
}

.footer {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid #eee;
    color: #666;
    font-size: 0.9rem;
}

/* Responsive Design */
/* Large tablets and small desktops */
@media (max-width: 1024px) {
    .container {
        padding: 35px 30px;
    }
    
    .contact-cards {
        grid-template-columns: repeat(2, 1fr);
        gap: 25px;
    }
}

/* Tablets */
@media (max-width: 768px) {
    .container {
        padding: 30px 20px;
    }

    .header h1 {
        font-size: 2.2rem;
    }
    
    .brand-name {
        font-size: 2.2rem;
    }
    
    .brand-name i {
        font-size: 2rem;
    }
    
    .brand-subtitle {
        font-size: 1.4rem;
    }

    .subtitle {
        font-size: 1.1rem;
    }

    .contact-cards {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }

    .contact-card {
        padding: 25px 20px;
    }
    
    .contact-card .icon {
        width: 70px;
        height: 70px;
        font-size: 1.8rem;
    }
}

/* Mobile landscape */
@media (max-width: 640px) {
    .contact-cards {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}

/* Mobile portrait */
@media (max-width: 480px) {
    body {
        padding: 10px;
    }
    
    .container {
        padding: 25px 15px;
        border-radius: 15px;
    }

    .header {
        margin-bottom: 30px;
    }

    .header h1 {
        font-size: 1.8rem;
    }
    
    .brand-name {
        font-size: 1.8rem;
        gap: 10px;
    }
    
    .brand-name i {
        font-size: 1.6rem;
    }
    
    .brand-subtitle {
        font-size: 1.1rem;
        letter-spacing: 1px;
    }

    .subtitle {
        font-size: 0.95rem;
        padding: 0 10px;
    }

    .contact-cards {
        grid-template-columns: 1fr;
        gap: 18px;
        margin-bottom: 30px;
    }

    .contact-card {
        padding: 20px 15px;
    }
    
    .contact-card .icon {
        width: 65px;
        height: 65px;
        font-size: 1.6rem;
        margin-bottom: 15px;
    }

    .contact-card h3 {
        font-size: 1.3rem;
        margin-bottom: 8px;
    }
    
    .contact-card p {
        font-size: 0.9rem;
        margin-bottom: 15px;
    }
    
    .contact-card .btn {
        padding: 10px 20px;
        font-size: 0.9rem;
    }
    
    .footer {
        padding-top: 20px;
        font-size: 0.85rem;
    }
}

/* Very small mobile */
@media (max-width: 360px) {
    .header h1 {
        font-size: 1.5rem;
    }
    
    .brand-name {
        font-size: 1.5rem;
    }
    
    .brand-name i {
        font-size: 1.3rem;
    }
    
    .brand-subtitle {
        font-size: 1rem;
    }
    
    .contact-card {
        padding: 18px 12px;
    }
    
    .contact-card .icon {
        width: 55px;
        height: 55px;
        font-size: 1.4rem;
    }
    
    .contact-card h3 {
        font-size: 1.1rem;
    }
    
    .contact-card .btn {
        padding: 8px 16px;
        font-size: 0.85rem;
    }
}

/* Landscape orientation */
@media (max-height: 500px) and (orientation: landscape) {
    .container {
        padding: 20px;
    }
    
    .header {
        margin-bottom: 20px;
    }
    
    .header h1 {
        font-size: 1.8rem;
    }
    
    .subtitle {
        font-size: 0.9rem;
    }
    
    .contact-cards {
        grid-template-columns: repeat(4, 1fr);
        gap: 15px;
        margin-bottom: 20px;
    }
    
    .contact-card {
        padding: 15px 10px;
    }
    
    .contact-card .icon {
        width: 50px;
        height: 50px;
        font-size: 1.3rem;
        margin-bottom: 10px;
    }
    
    .contact-card h3 {
        font-size: 1rem;
        margin-bottom: 5px;
    }
    
    .contact-card p {
        font-size: 0.8rem;
        margin-bottom: 10px;
    }
    
    .contact-card .btn {
        padding: 8px 15px;
        font-size: 0.85rem;
    }
}