/* === Design System Variables === */
:root {
    /* Background layers */
    --bg-base: #0B1120;
    --bg-surface: #111827;
    --bg-card: #1F2937;
    --bg-card-hover: #374151;
    --bg-input: #111827;
    --bg-modal: rgba(0, 0, 0, 0.6);

    /* Text */
    --text-primary: #F9FAFB;
    --text-secondary: #D1D5DB;
    --text-muted: #9CA3AF;
    --text-dim: #6B7280;

    /* Accent colors */
    --accent-blue: #3B82F6;
    --accent-blue-hover: #2563EB;
    --accent-violet: #8B5CF6;
    --accent-violet-hover: #7C3AED;
    --accent-emerald: #10B981;
    --accent-amber: #F59E0B;
    --accent-rose: #F43F5E;
    --accent-cyan: #06B6D4;

    /* Borders */
    --border-subtle: rgba(255, 255, 255, 0.06);
    --border-default: rgba(255, 255, 255, 0.1);
    --border-strong: rgba(255, 255, 255, 0.2);

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --shadow-glow-blue: 0 0 20px rgba(59, 130, 246, 0.15);
    --shadow-glow-violet: 0 0 20px rgba(139, 92, 246, 0.15);

    /* Spacing */
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
}

/* === Reset === */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* === Base === */
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background: var(--bg-base);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

/* === Header === */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 32px;
    background: var(--bg-surface);
    border-bottom: 1px solid var(--border-subtle);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(12px);
}

.header-left {
    display: flex;
    align-items: center;
    gap: 14px;
}

.logo-icon {
    width: 36px;
    height: 36px;
    color: var(--accent-blue);
    flex-shrink: 0;
}

.header-text h1 {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.3;
}

.header-subtitle {
    font-size: 13px;
    color: var(--text-muted);
}

.header-right {
    display: flex;
    align-items: center;
    gap: 12px;
}

.status-badge {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 14px;
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.2);
    border-radius: 20px;
    font-size: 13px;
    color: var(--accent-emerald);
    font-weight: 500;
}

.status-dot {
    width: 8px;
    height: 8px;
    background: var(--accent-emerald);
    border-radius: 50%;
    animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 1; box-shadow: 0 0 0 0 rgba(16, 185, 129, 0.4); }
    50% { opacity: 0.8; box-shadow: 0 0 0 6px rgba(16, 185, 129, 0); }
}

/* === Container === */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 24px 32px;
}

/* === Tabs === */
.tabs {
    display: flex;
    gap: 4px;
    margin-bottom: 24px;
    padding: 4px;
    background: var(--bg-surface);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-subtle);
}

.tab {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
    background: transparent;
    color: var(--text-muted);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: all var(--transition-fast);
    white-space: nowrap;
    flex: 1;
    justify-content: center;
}

.tab svg {
    width: 18px;
    height: 18px;
    flex-shrink: 0;
}

.tab:hover {
    color: var(--text-secondary);
    background: var(--bg-card);
}

.tab.active {
    color: var(--text-primary);
    background: var(--bg-card);
    box-shadow: var(--shadow-sm);
}

/* === Tab Content === */
.tab-content {
    display: none;
    animation: fadeIn 0.2s ease;
}

.tab-content.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(4px); }
    to { opacity: 1; transform: translateY(0); }
}

/* === Stats Grid === */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-bottom: 24px;
}

.stat-card {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 20px;
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-subtle);
    transition: all var(--transition-fast);
}

.stat-card:hover {
    border-color: var(--border-default);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.stat-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    flex-shrink: 0;
}

.stat-icon svg {
    width: 24px;
    height: 24px;
}

.stat-uptime .stat-icon { background: rgba(59, 130, 246, 0.1); color: var(--accent-blue); }
.stat-peers .stat-icon { background: rgba(16, 185, 129, 0.1); color: var(--accent-emerald); }
.stat-sent .stat-icon { background: rgba(139, 92, 246, 0.1); color: var(--accent-violet); }
.stat-recv .stat-icon { background: rgba(6, 182, 212, 0.1); color: var(--accent-cyan); }

.stat-info {
    display: flex;
    flex-direction: column;
    min-width: 0;
}

.stat-label {
    font-size: 13px;
    color: var(--text-muted);
    font-weight: 500;
    margin-bottom: 4px;
}

.stat-value {
    font-size: 22px;
    font-weight: 700;
    color: var(--text-primary);
    font-variant-numeric: tabular-nums;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* === Cards === */
.card {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-subtle);
    padding: 24px;
    margin-bottom: 16px;
}

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 20px;
}

.card-header h2 {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
}

/* === Buttons === */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.btn-primary {
    background: var(--accent-blue);
    color: #fff;
}

.btn-primary:hover {
    background: var(--accent-blue-hover);
    box-shadow: var(--shadow-glow-blue);
}

.btn-ghost {
    background: transparent;
    color: var(--text-muted);
    border: 1px solid var(--border-default);
}

.btn-ghost:hover {
    color: var(--text-secondary);
    background: var(--bg-card-hover);
    border-color: var(--border-strong);
}

.btn-danger {
    background: rgba(244, 63, 94, 0.1);
    color: var(--accent-rose);
    border: 1px solid rgba(244, 63, 94, 0.2);
}

.btn-danger:hover {
    background: rgba(244, 63, 94, 0.2);
}

.btn-warning {
    background: rgba(245, 158, 11, 0.1);
    color: var(--accent-amber);
    border: 1px solid rgba(245, 158, 11, 0.2);
}

.btn-warning:hover {
    background: rgba(245, 158, 11, 0.2);
}

.btn-sm {
    padding: 6px 12px;
    font-size: 13px;
}

.btn-icon {
    padding: 6px;
    border-radius: var(--radius-sm);
}

.btn-icon svg {
    width: 16px;
    height: 16px;
}

/* === Data Tables === */
.data-table {
    width: 100%;
    border-collapse: collapse;
}

.data-table th {
    text-align: left;
    padding: 10px 16px;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-bottom: 1px solid var(--border-default);
    background: rgba(0, 0, 0, 0.15);
}

.data-table td {
    padding: 12px 16px;
    font-size: 14px;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border-subtle);
}

.data-table tr:last-child td {
    border-bottom: none;
}

.data-table tr:hover td {
    background: rgba(255, 255, 255, 0.02);
}

.data-table .mono {
    font-family: 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;
    font-size: 13px;
    color: var(--accent-cyan);
}

.data-table .actions {
    display: flex;
    gap: 6px;
    justify-content: flex-end;
}

/* === Item Cards (for simpler views) === */
.peer-item, .room-item, .key-item, .log-item {
    padding: 16px;
    margin-bottom: 8px;
    background: rgba(0, 0, 0, 0.15);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-subtle);
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: all var(--transition-fast);
}

.peer-item:hover, .room-item:hover, .key-item:hover, .log-item:hover {
    border-color: var(--border-default);
    background: rgba(0, 0, 0, 0.2);
}

.item-info {
    display: flex;
    flex-direction: column;
    gap: 4px;
    min-width: 0;
}

.item-name {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 14px;
}

.item-meta {
    font-size: 13px;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.item-meta .separator {
    color: var(--border-strong);
}

.item-actions {
    display: flex;
    gap: 6px;
    flex-shrink: 0;
}

/* === Tags/Badges === */
.badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
}

.badge-success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--accent-emerald);
    border: 1px solid rgba(16, 185, 129, 0.2);
}

.badge-danger {
    background: rgba(244, 63, 94, 0.1);
    color: var(--accent-rose);
    border: 1px solid rgba(244, 63, 94, 0.2);
}

.badge-info {
    background: rgba(59, 130, 246, 0.1);
    color: var(--accent-blue);
    border: 1px solid rgba(59, 130, 246, 0.2);
}

/* === Empty State === */
.empty {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 48px 20px;
    color: var(--text-dim);
}

.empty svg {
    width: 48px;
    height: 48px;
    margin-bottom: 12px;
    opacity: 0.4;
}

.empty-text {
    font-size: 14px;
}

/* === Loading Skeleton === */
.loading-skeleton {
    padding: 16px 0;
}

.skeleton-line {
    height: 16px;
    background: linear-gradient(90deg, var(--bg-card-hover) 25%, rgba(255,255,255,0.05) 50%, var(--bg-card-hover) 75%);
    background-size: 200% 100%;
    animation: shimmer 1.5s ease-in-out infinite;
    border-radius: var(--radius-sm);
    margin-bottom: 10px;
}

.skeleton-line.short {
    width: 60%;
}

@keyframes shimmer {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* === Modal === */
.modal-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: var(--bg-modal);
    backdrop-filter: blur(4px);
    z-index: 200;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.15s ease;
}

.modal-overlay.active {
    display: flex;
}

.modal {
    background: var(--bg-card);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-xl);
    width: 90%;
    max-width: 440px;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.2s ease;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px 0;
}

.modal-header h3 {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
}

.modal-close {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 4px;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.modal-close:hover {
    color: var(--text-primary);
    background: var(--bg-card-hover);
}

.modal-body {
    padding: 20px 24px 24px;
}

/* === Form === */
.form-group {
    margin-bottom: 16px;
}

.form-label {
    display: block;
    font-size: 13px;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 6px;
}

.form-input {
    width: 100%;
    padding: 10px 14px;
    background: var(--bg-input);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 14px;
    transition: all var(--transition-fast);
    outline: none;
    font-family: inherit;
}

.form-input:focus {
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.form-input::placeholder {
    color: var(--text-dim);
}

.form-hint {
    font-size: 12px;
    color: var(--text-dim);
    margin-top: 4px;
}

.form-actions {
    display: flex;
    gap: 8px;
    justify-content: flex-end;
    margin-top: 20px;
}

.btn-cancel {
    background: var(--bg-card-hover);
    color: var(--text-secondary);
    border: 1px solid var(--border-default);
}

.btn-cancel:hover {
    background: rgba(255, 255, 255, 0.1);
}

/* === Status Detail List === */
.status-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.status-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 14px;
    background: rgba(0, 0, 0, 0.15);
    border-radius: var(--radius-md);
}

.status-row-label {
    font-size: 13px;
    color: var(--text-muted);
}

.status-row-value {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
    font-family: 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;
}

/* === Peer Count Badge === */
.peer-count {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 24px;
    height: 24px;
    padding: 0 8px;
    background: rgba(59, 130, 246, 0.1);
    color: var(--accent-blue);
    border-radius: 12px;
    font-size: 13px;
    font-weight: 600;
}

/* === Scrollbar === */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--border-default);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--border-strong);
}

/* === Responsive === */
@media (max-width: 768px) {
    .header { padding: 12px 16px; }
    .container { padding: 16px; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; }
    .tabs { overflow-x: auto; }
    .tab span { display: none; }
    .tab svg { width: 20px; height: 20px; }
    .tab { padding: 10px 14px; }
    .stat-card { padding: 14px; }
    .stat-value { font-size: 18px; }
    .peer-item, .room-item, .key-item, .log-item { flex-direction: column; align-items: flex-start; gap: 10px; }
    .item-actions { align-self: flex-end; }
}

@media (max-width: 480px) {
    .stats-grid { grid-template-columns: 1fr 1fr; gap: 8px; }
    .stat-icon { width: 40px; height: 40px; }
    .stat-icon svg { width: 20px; height: 20px; }
}