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

body {
    font-family: "Segoe UI", Tahoma, Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
    line-height: 1.7;
}

header {
    background: rgba(255, 255, 255, 0.95);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 1rem;
    padding: 0 1rem;
}

nav a {
    text-decoration: none;
    color: #4a5568;
    font-weight: 600;
    padding: 0.5rem 1.2rem;
    border-radius: 25px;
    transition: all 0.3s ease;
}

nav a:hover {
    background: #667eea;
    color: white;
    transform: translateY(-2px);
}

nav a.active {
    background: #667eea;
    color: white;
}

main {
    max-width: 900px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.card {
    background: white;
    border-radius: 15px;
    padding: 2.5rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
    animation: fadeIn 0.6s ease-out;
}

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

h1 {
    color: #2d3748;
    margin-bottom: 0.5rem;
    font-size: 2rem;
}

h2.features-label {
    color: #2d3748;
    font-size: 1.25rem;
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

.subtitle {
    color: #718096;
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid #e2e8f0;
}

.content {
    color: #4a5568;
    margin-bottom: 1rem;
    font-size: 1.05rem;
}

.features {
    list-style: none;
    margin-top: 0.5rem;
}

.features li {
    background: #f7fafc;
    padding: 0.8rem 1.2rem;
    margin-bottom: 0.5rem;
    border-left: 4px solid #667eea;
    border-radius: 8px;
    transition: transform 0.2s ease;
}

.features li:hover {
    transform: translateX(5px);
    background: #edf2f7;
}

footer {
    text-align: center;
    color: #718096;
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid #e2e8f0;
    font-size: 0.9rem;
}

footer .version {
    font-family: ui-monospace, "SF Mono", Menlo, monospace;
    color: #a0aec0;
    font-size: 0.85rem;
}

.loading {
    text-align: center;
    color: #718096;
    padding: 2rem;
    font-size: 1.1rem;
}

.error {
    background: #fed7d7;
    color: #c53030;
    padding: 1rem;
    border-radius: 8px;
    text-align: center;
}