*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
    --primary: #2563eb; --primary-dark: #1d4ed8; --success: #16a34a; --danger: #dc2626;
    --warning: #f59e0b; --gray-50: #f9fafb; --gray-100: #f3f4f6; --gray-200: #e5e7eb;
    --gray-300: #d1d5db; --gray-500: #6b7280; --gray-700: #374151; --gray-900: #111827;
    --sidebar-w: 240px; --radius: 8px;
}
body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif; background: var(--gray-50); color: var(--gray-900); min-height: 100vh; }
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Sidebar */
.sidebar { position: fixed; top: 0; left: 0; width: var(--sidebar-w); height: 100vh; background: var(--gray-900); color: #fff; overflow-y: auto; z-index: 100; display: flex; flex-direction: column; }
.sidebar-header { padding: 20px; border-bottom: 1px solid var(--gray-700); }
.sidebar-header h2 { font-size: 1.4rem; }
.sidebar-header small { color: var(--gray-500); }
.sidebar ul { list-style: none; flex: 1; padding: 10px 0; }
.sidebar li a { display: block; padding: 8px 20px; color: var(--gray-300); font-size: 0.9rem; transition: background 0.2s; }
.sidebar li a:hover, .sidebar li a.active { background: var(--gray-700); color: #fff; text-decoration: none; }
.nav-section { padding: 12px 20px 4px; font-size: 0.7rem; text-transform: uppercase; letter-spacing: 1px; color: var(--gray-500); }
.sidebar-footer { padding: 15px 20px; border-top: 1px solid var(--gray-700); font-size: 0.85rem; display: flex; justify-content: space-between; align-items: center; }
.sidebar-footer a { color: var(--gray-500); }

/* Content */
.content { margin-left: var(--sidebar-w); padding: 30px; min-height: 100vh; }
.content h1 { font-size: 1.6rem; margin-bottom: 20px; }
.content h2 { font-size: 1.2rem; margin-bottom: 12px; }

/* Login */
.login-page { display: flex; align-items: center; justify-content: center; min-height: 100vh; background: linear-gradient(135deg, var(--gray-900), var(--primary-dark)); }
.login-box { background: #fff; padding: 40px; border-radius: var(--radius); width: 400px; max-width: 90%; box-shadow: 0 20px 60px rgba(0,0,0,0.3); }
.login-box h1 { font-size: 2rem; text-align: center; color: var(--primary); }
.login-box p { text-align: center; color: var(--gray-500); margin-bottom: 24px; }

/* Forms */
.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-weight: 600; font-size: 0.85rem; margin-bottom: 4px; color: var(--gray-700); }
.form-group input, .form-group select, .form-group textarea {
    width: 100%; padding: 8px 12px; border: 1px solid var(--gray-300); border-radius: var(--radius);
    font-size: 0.95rem; transition: border 0.2s;
}
.form-group input:focus, .form-group select:focus, .form-group textarea:focus { border-color: var(--primary); outline: none; box-shadow: 0 0 0 3px rgba(37,99,235,0.1); }
.form-group textarea { resize: vertical; min-height: 100px; }
.form-group small { color: var(--gray-500); font-size: 0.8rem; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-actions { margin-top: 20px; display: flex; gap: 10px; }

/* Buttons */
.btn { display: inline-block; padding: 8px 18px; border: none; border-radius: var(--radius); font-size: 0.9rem; cursor: pointer; font-weight: 500; transition: background 0.2s; text-align: center; }
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); }
.btn-secondary { background: var(--gray-200); color: var(--gray-700); }
.btn-secondary:hover { background: var(--gray-300); }
.btn-danger { background: var(--danger); color: #fff; }
.btn-danger:hover { background: #b91c1c; }
.btn-sm { padding: 4px 10px; font-size: 0.8rem; }
.btn-full { width: 100%; }

/* Tables */
.table { width: 100%; border-collapse: collapse; background: #fff; border-radius: var(--radius); overflow: hidden; box-shadow: 0 1px 3px rgba(0,0,0,0.1); }
.table th { background: var(--gray-100); text-align: left; padding: 10px 14px; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.5px; color: var(--gray-500); border-bottom: 2px solid var(--gray-200); }
.table td { padding: 10px 14px; border-bottom: 1px solid var(--gray-100); font-size: 0.9rem; }
.table tr:hover td { background: var(--gray-50); }
.table .actions { white-space: nowrap; }
.table .actions a { margin-right: 8px; }

/* Alerts */
.alert { padding: 12px 16px; border-radius: var(--radius); margin-bottom: 20px; font-size: 0.9rem; }
.alert-success { background: #dcfce7; color: #166534; border: 1px solid #bbf7d0; }
.alert-error { background: #fef2f2; color: #991b1b; border: 1px solid #fecaca; }
.alert-warning { background: #fffbeb; color: #92400e; border: 1px solid #fde68a; }

/* Stats */
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 16px; margin-bottom: 30px; }
.stat-card { background: #fff; padding: 20px; border-radius: var(--radius); box-shadow: 0 1px 3px rgba(0,0,0,0.1); text-align: center; }
.stat-number { font-size: 2rem; font-weight: 700; color: var(--primary); }
.stat-label { font-size: 0.85rem; color: var(--gray-500); margin-top: 4px; }

/* Cards */
.section-card { background: #fff; padding: 20px; border-radius: var(--radius); box-shadow: 0 1px 3px rgba(0,0,0,0.1); margin-bottom: 20px; }
.section-card.warning { border-left: 4px solid var(--warning); }
.section-card h2 { margin-bottom: 12px; }

/* Quick actions */
.quick-actions { display: flex; flex-wrap: wrap; gap: 10px; }

/* Badge */
.badge { display: inline-block; padding: 2px 8px; border-radius: 12px; font-size: 0.75rem; font-weight: 600; background: var(--gray-200); color: var(--gray-700); }
.badge-active { background: #dcfce7; color: #166534; }
.badge-inactive { background: #fef2f2; color: #991b1b; }

/* Toolbar */
.toolbar { display: flex; justify-content: space-between; align-items: center; margin-bottom: 20px; flex-wrap: wrap; gap: 10px; }

/* Topology grid */
.topo-grid { overflow-x: auto; }
.topo-grid table { border-collapse: collapse; }
.topo-grid th, .topo-grid td { padding: 6px 10px; text-align: center; font-size: 0.8rem; border: 1px solid var(--gray-200); min-width: 40px; }
.topo-grid th { background: var(--gray-100); position: sticky; top: 0; }
.topo-grid .topo-link { background: var(--primary); color: #fff; border-radius: 4px; display: inline-block; width: 24px; height: 24px; line-height: 24px; font-size: 0.7rem; }
.topo-grid .topo-self { background: var(--gray-300); }
.topo-grid .topo-reciprocal { background: var(--warning); color: #fff; }

/* Responsive */
@media (max-width: 768px) {
    .sidebar { width: 100%; height: auto; position: relative; }
    .content { margin-left: 0; }
    .form-row { grid-template-columns: 1fr; }
}