:root {
    --primary: #dc2626;
    --primary-dark: #b91c1c;
    --primary-light: #ef4444;
    --secondary: #991b1b;
    --text: #1f2937;
    --text-muted: #6b7280;
    --bg: #fef2f2;
    --card-bg: #ffffff;
    --radius: 16px;
    --shadow: 0 4px 6px -1px rgba(220, 38, 38, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(220, 38, 38, 0.1);
    --transition: all 0.3s ease;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg);
    color: var(--text);
    margin: 0;
    min-height: 100vh;
    line-height: 1.6;
}

.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.app-header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    padding: 4rem 0;
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.app-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.app-subtitle {
    font-size: 1.2rem;
    opacity: 0.95;
    font-weight: 300;
}

.app-main {
    flex: 1;
    padding: 4rem 0;
}

.features-section {
    margin-bottom: 4rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    align-items: stretch;
}

@media (min-width: 768px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 992px) {
    .features-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

.feature-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 2.5rem;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 2px solid transparent;
    text-align: center;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-light);
}

.feature-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    color: white;
    font-size: 2rem;
    box-shadow: var(--shadow);
}

.feature-card h3 {
    color: var(--primary);
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.feature-card p {
    color: var(--text-muted);
    margin: 0 0 auto 0;
    font-size: 1rem;
    flex-grow: 1;
}

.feature-card .btn {
    margin-top: auto;
}

.hero-section {
    text-align: center;
    padding: 3rem 0;
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-top: 2rem;
}

.hero-content h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--primary);
}

.hero-content p {
    color: var(--text-muted);
    font-size: 1.2rem;
    margin-bottom: 2.5rem;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border: none;
    padding: 0.875rem 2.5rem;
    font-weight: 600;
    border-radius: 50px;
    transition: var(--transition);
    color: white;
    text-decoration: none;
    display: inline-block;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    background: linear-gradient(135deg, var(--primary-light), var(--primary));
    color: white;
}

.btn-outline-primary {
    border: 2px solid var(--primary);
    color: var(--primary);
    padding: 0.875rem 2.5rem;
    font-weight: 600;
    border-radius: 50px;
    transition: var(--transition);
    background: transparent;
    text-decoration: none;
    display: inline-block;
}

.btn-outline-primary:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.app-footer {
    background: var(--text);
    color: white;
    padding: 2rem 0;
    text-align: center;
    margin-top: auto;
}

.app-footer p {
    margin: 0;
    opacity: 0.9;
}

/* Feature List Styles - Dùng cho các trang mẫu */
.back-link {
    margin-bottom: 2rem;
}

.feature-demo {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 3rem;
    margin: 2rem 0;
    box-shadow: var(--shadow);
}

.feature-list {
    list-style: none;
    padding: 0;
    max-width: 800px;
    margin: 0 auto;
}

.feature-list li {
    padding: 1.5rem;
    margin: 1rem 0;
    background: var(--card-bg);
    border: 2px solid #e5e7eb;
    border-radius: var(--radius);
    transition: var(--transition);
    box-shadow: var(--shadow);
    display: flex;
    align-items: flex-start;
}

.feature-list li:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-light);
}

.feature-list li i {
    color: var(--primary);
    margin-right: 1rem;
    font-size: 1.25rem;
    margin-top: 0.25rem;
    flex-shrink: 0;
}

.feature-list li strong {
    color: var(--primary);
    display: block;
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.feature-list li span {
    color: var(--text-muted);
    display: block;
}

.back-button-bottom {
    text-align: center;
    margin-top: 3rem;
    padding-top: 2rem;
}

.btn-outline-light {
    border: 2px solid rgba(255, 255, 255, 0.8);
    color: white;
    padding: 0.875rem 2rem;
    font-weight: 600;
    border-radius: 50px;
    transition: var(--transition);
    background: transparent;
    text-decoration: none;
    display: inline-block;
}

.btn-outline-light:hover {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

@media (max-width: 768px) {
    .app-title {
        font-size: 2rem;
    }
    
    .hero-content h2 {
        font-size: 1.8rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn-primary,
    .btn-outline-primary {
        width: 100%;
        max-width: 300px;
    }
    
    .feature-list {
        max-width: 100%;
    }
    
    .feature-list li {
        padding: 1rem;
    }
}