:root{--primary: #4f46e5;--primary-hover: #4338ca;--primary-light: #eef2ff;--secondary: #6b7280;--success: #10b981;--warning: #f59e0b;--danger: #ef4444;--bg: #f9fafb;--bg-card: #ffffff;--text: #111827;--text-secondary: #6b7280;--border: #e5e7eb;--sidebar-bg: #1e1b4b;--sidebar-text: #c7d2fe;--sidebar-active: #4f46e5;--radius: 8px;--shadow: 0 1px 3px rgba(0, 0, 0, .1);--shadow-lg: 0 4px 12px rgba(0, 0, 0, .1)}*{margin:0;padding:0;box-sizing:border-box}body{font-family:Inter,-apple-system,BlinkMacSystemFont,sans-serif;background:var(--bg);color:var(--text);line-height:1.5}.input{width:100%;padding:10px 14px;border:1px solid var(--border);border-radius:var(--radius);font-size:14px;font-family:inherit;transition:border-color .2s;outline:none}.input:focus{border-color:var(--primary);box-shadow:0 0 0 3px #4f46e51a}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:10px 20px;border:none;border-radius:var(--radius);font-size:14px;font-weight:500;font-family:inherit;cursor:pointer;transition:all .2s;text-decoration:none}.btn-primary{background:var(--primary);color:#fff}.btn-primary:hover{background:var(--primary-hover)}.btn-primary:disabled{background:#a5b4fc;cursor:not-allowed}.btn-secondary{background:#fff;color:var(--text);border:1px solid var(--border)}.btn-secondary:hover{background:var(--bg)}.btn-danger{background:var(--danger);color:#fff}.btn-danger:hover{background:#dc2626}.btn-sm{padding:6px 12px;font-size:13px}.card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow)}.form-group{margin-bottom:16px}.form-group label{display:block;margin-bottom:6px;font-size:14px;font-weight:500;color:var(--text)}.badge{display:inline-flex;align-items:center;padding:2px 10px;border-radius:9999px;font-size:12px;font-weight:500}.badge-admin{background:#fef3c7;color:#92400e}.badge-instructor{background:#dbeafe;color:#1e40af}.badge-student{background:#d1fae5;color:#065f46}.alert{padding:12px 16px;border-radius:var(--radius);font-size:14px;margin-bottom:16px}.alert-error{background:#fef2f2;color:#991b1b;border:1px solid #fecaca}.alert-success{background:#f0fdf4;color:#166534;border:1px solid #bbf7d0}.table-wrapper{overflow-x:auto}table{width:100%;border-collapse:collapse}th,td{text-align:left;padding:12px 16px;border-bottom:1px solid var(--border)}th{font-size:12px;font-weight:600;text-transform:uppercase;letter-spacing:.05em;color:var(--text-secondary);background:var(--bg)}tr:hover td{background:var(--primary-light)}