*, *::before, *::after {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
    overflow-x: hidden;
    width: 100vw;
}

:root {
    --primary: #667eea;
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary: #2c3e50;
    --accent: #3498db;
    --bg-light: #f5f5f5;
    --text-dark: #333;
    --text-medium: #555;
    --text-light: #666;
    --text-muted: #999;
    --border-color: #e0e0e0;
    --danger: #e74c3c;
    --danger-bg: #f8d7da;
    --danger-border: #f5c6cb;
    --success: #27ae60;
    --success-bg: #d4edda;
    --success-border: #c3e6cb;
    --radius: 8px;
    --shadow: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-hover: 0 4px 12px rgba(0,0,0,0.15);
}

body {
    font-family: Arial, sans-serif;
    background-color: var(--bg-light);
    color: var(--text-dark);
    padding-top: 70px;
}

.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

h1 { color: var(--text-dark); }
h2 { color: var(--secondary); }
h3 { color: var(--secondary); margin-top: 0; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.back-link {
    color: var(--accent);
    text-decoration: none;
    margin-bottom: 20px;
    display: inline-block;
}
.back-link:hover { text-decoration: underline; }

/* Responsive basics */
@media (max-width: 768px) {
    .content-grid, .model-grid { grid-template-columns: 1fr; }
}