/* =============================================== */
/* MODERN DESIGN SYSTEM - Clean, Fast, Fluid      */
/* =============================================== */

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

:root {
    /* Colors - Clean & Professional */
    --primary: #6366f1;
    --primary-hover: #4f46e5;
    --primary-light: #e0e7ff;
    --primary-bg: #eef2ff;
    
    --success: #10b981;
    --success-light: #d1fae5;
    --warning: #f59e0b;
    --warning-light: #fef3c7;
    --danger: #ef4444;
    --danger-light: #fee2e2;
    --info: #3b82f6;
    --info-light: #dbeafe;
    
    /* Neutrals */
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;
    
    /* Semantic */
    --bg: var(--gray-50);
    --surface: #ffffff;
    --border: var(--gray-200);
    --text: var(--gray-800);
    --text-secondary: var(--gray-500);
    --text-muted: var(--gray-400);
    
    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    
    /* Radius */
    --radius-sm: 0.375rem;
    --radius: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Shadows - Subtle */
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
    --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -2px rgba(0,0,0,0.05);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -4px rgba(0,0,0,0.04);
    
    /* Transitions */
    --transition: 150ms ease;
    --transition-slow: 250ms ease;
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
    :root.auto-theme {
        --bg: var(--gray-900);
        --surface: var(--gray-800);
        --border: var(--gray-700);
        --text: var(--gray-100);
        --text-secondary: var(--gray-400);
        --text-muted: var(--gray-500);
    }
}

html {
    font-size: 15px;
    scroll-behavior: smooth;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5;
    min-height: 100vh;
    text-rendering: optimizeSpeed;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.25;
    color: var(--text);
}
h1 { font-size: 1.75rem; }
h2 { font-size: 1.375rem; }
h3 { font-size: 1.125rem; }

p { margin-bottom: var(--space-4); }
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* --- Layout --- */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-4);
}

.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.gap-1 { gap: var(--space-1); }
.gap-2 { gap: var(--space-2); }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }

.grid { display: grid; }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 768px) {
    .grid-cols-2, .grid-cols-3, .grid-cols-4 { grid-template-columns: 1fr; }
}

/* --- Card --- */
.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--space-5);
    box-shadow: var(--shadow-sm);
}
.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-4);
    padding-bottom: var(--space-3);
    border-bottom: 1px solid var(--border);
}
.card-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text);
}

/* --- Buttons --- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-2) var(--space-4);
    font-size: 0.875rem;
    font-weight: 500;
    line-height: 1.5;
    border: 1px solid transparent;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all var(--transition);
    white-space: nowrap;
}
.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}
.btn-sm {
    padding: var(--space-1) var(--space-3);
    font-size: 0.8125rem;
}
.btn-lg {
    padding: var(--space-3) var(--space-6);
    font-size: 1rem;
}

.btn-primary {
    background: var(--primary);
    color: white;
}
.btn-primary:hover:not(:disabled) {
    background: var(--primary-hover);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text);
    border-color: var(--border);
}
.btn-secondary:hover:not(:disabled) {
    background: var(--gray-100);
    border-color: var(--gray-300);
}

.btn-success {
    background: var(--success);
    color: white;
}
.btn-success:hover:not(:disabled) {
    opacity: 0.9;
}

.btn-danger {
    background: var(--danger);
    color: white;
}
.btn-danger:hover:not(:disabled) {
    opacity: 0.9;
}

.btn-ghost {
    background: transparent;
    color: var(--text-secondary);
}
.btn-ghost:hover:not(:disabled) {
    background: var(--gray-100);
    color: var(--text);
}

/* --- Inputs --- */
.input, .select, .textarea {
    width: 100%;
    padding: var(--space-2) var(--space-3);
    font-size: 0.9375rem;
    line-height: 1.5;
    color: var(--text);
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    transition: border-color var(--transition), box-shadow var(--transition);
}
.input:focus, .select:focus, .textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-light);
}
.input::placeholder { color: var(--text-muted); }
.textarea { resize: vertical; min-height: 80px; }
.select { cursor: pointer; }

.input-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-1);
}
.label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
}

/* --- Tabs --- */
.tabs {
    display: flex;
    gap: var(--space-1);
    border-bottom: 1px solid var(--border);
    margin-bottom: var(--space-4);
    overflow-x: auto;
}
.tab {
    padding: var(--space-3) var(--space-4);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition);
    white-space: nowrap;
}
.tab:hover {
    color: var(--text);
}
.tab.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
}
.tab-content {
    display: none;
}
.tab-content.active {
    display: block;
    animation: fadeIn 0.2s ease;
}

/* --- Modal --- */
.modal {
    position: fixed;
    inset: 0;
    z-index: 1000;
    display: none;
    align-items: center;
    justify-content: center;
    padding: var(--space-4);
}
.modal.show {
    display: flex;
}
.modal-backdrop {
    position: absolute;
    inset: 0;
    background: rgba(0,0,0,0.4);
    backdrop-filter: blur(2px);
}
.modal-content {
    position: relative;
    background: var(--surface);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    max-width: 500px;
    width: 100%;
    max-height: 90vh;
    overflow: auto;
}
.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-4) var(--space-5);
    border-bottom: 1px solid var(--border);
}
.modal-title {
    font-size: 1.125rem;
    font-weight: 600;
}
.modal-close {
    padding: var(--space-1);
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    border-radius: var(--radius-sm);
}
.modal-close:hover {
    background: var(--gray-100);
    color: var(--text);
}
.modal-body {
    padding: var(--space-5);
}
.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: var(--space-3);
    padding: var(--space-4) var(--space-5);
    border-top: 1px solid var(--border);
}

/* --- Table --- */
.table-container {
    overflow-x: auto;
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
}
.table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
}
.table th, .table td {
    padding: var(--space-3) var(--space-4);
    text-align: left;
    border-bottom: 1px solid var(--border);
}
.table th {
    font-weight: 600;
    color: var(--text-secondary);
    background: var(--gray-50);
}
.table tr:last-child td {
    border-bottom: none;
}
.table tr:hover td {
    background: var(--gray-50);
}

/* --- Badges --- */
.badge {
    display: inline-flex;
    align-items: center;
    padding: var(--space-1) var(--space-2);
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
}
.badge-primary { background: var(--primary-light); color: var(--primary); }
.badge-success { background: var(--success-light); color: var(--success); }
.badge-warning { background: var(--warning-light); color: var(--warning); }
.badge-danger { background: var(--danger-light); color: var(--danger); }
.badge-info { background: var(--info-light); color: var(--info); }

/* --- Alerts --- */
.alert {
    padding: var(--space-3) var(--space-4);
    border-radius: var(--radius);
    font-size: 0.875rem;
}
.alert-info { background: var(--info-light); color: var(--info); border: 1px solid var(--info); }
.alert-success { background: var(--success-light); color: var(--success); border: 1px solid var(--success); }
.alert-warning { background: var(--warning-light); color: #92400e; border: 1px solid var(--warning); }
.alert-danger { background: var(--danger-light); color: var(--danger); border: 1px solid var(--danger); }

/* --- Loading --- */
.spinner {
    width: 24px;
    height: 24px;
    border: 2px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}

.loading-overlay {
    position: fixed;
    inset: 0;
    z-index: 9999;
    display: none;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    gap: var(--space-4);
    background: rgba(255,255,255,0.9);
    backdrop-filter: blur(4px);
}
.loading-overlay.show {
    display: flex;
}
.loading-overlay .spinner {
    width: 40px;
    height: 40px;
    border-width: 3px;
}

/* --- Toast --- */
.toast {
    position: fixed;
    bottom: var(--space-6);
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    padding: var(--space-3) var(--space-5);
    background: var(--gray-800);
    color: white;
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 10000;
}
.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

/* --- Sidebar / Navigation --- */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 240px;
    height: 100vh;
    background: var(--surface);
    border-right: 1px solid var(--border);
    padding: var(--space-4);
    display: flex;
    flex-direction: column;
    z-index: 100;
}
.sidebar-header {
    padding: var(--space-2) 0 var(--space-4);
    border-bottom: 1px solid var(--border);
    margin-bottom: var(--space-4);
}
.sidebar-brand {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--primary);
}
.sidebar-nav {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--space-1);
}
.sidebar-link {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-2) var(--space-3);
    font-size: 0.875rem;
    color: var(--text-secondary);
    border-radius: var(--radius);
    transition: all var(--transition);
}
.sidebar-link:hover {
    background: var(--gray-100);
    color: var(--text);
    text-decoration: none;
}
.sidebar-link.active {
    background: var(--primary-bg);
    color: var(--primary);
    font-weight: 500;
}
.sidebar-footer {
    padding-top: var(--space-4);
    border-top: 1px solid var(--border);
}

.main-content {
    margin-left: 240px;
    padding: var(--space-6);
    min-height: 100vh;
}

@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
        transition: transform 0.3s ease;
    }
    .sidebar.open {
        transform: translateX(0);
    }
    .main-content {
        margin-left: 0;
    }
}

/* --- Utility Classes --- */
.hidden { display: none !important; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); border: 0; }

.text-center { text-align: center; }
.text-right { text-align: right; }
.text-sm { font-size: 0.875rem; }
.text-xs { font-size: 0.75rem; }
.text-muted { color: var(--text-muted); }
.text-secondary { color: var(--text-secondary); }
.text-primary { color: var(--primary); }
.text-success { color: var(--success); }
.text-danger { color: var(--danger); }

.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }

.mt-1 { margin-top: var(--space-1); }
.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mb-1 { margin-bottom: var(--space-1); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }

.p-2 { padding: var(--space-2); }
.p-3 { padding: var(--space-3); }
.p-4 { padding: var(--space-4); }
.p-5 { padding: var(--space-5); }
.px-4 { padding-left: var(--space-4); padding-right: var(--space-4); }
.py-2 { padding-top: var(--space-2); padding-bottom: var(--space-2); }

.w-full { width: 100%; }
.max-w-md { max-width: 28rem; }
.max-w-lg { max-width: 32rem; }
.max-w-xl { max-width: 36rem; }

.rounded { border-radius: var(--radius); }
.rounded-lg { border-radius: var(--radius-lg); }
.shadow { box-shadow: var(--shadow); }
.shadow-md { box-shadow: var(--shadow-md); }

.border { border: 1px solid var(--border); }
.border-t { border-top: 1px solid var(--border); }
.border-b { border-bottom: 1px solid var(--border); }

.bg-surface { background: var(--surface); }
.bg-gray-50 { background: var(--gray-50); }
.bg-gray-100 { background: var(--gray-100); }

.overflow-auto { overflow: auto; }
.overflow-hidden { overflow: hidden; }

/* --- Animations --- */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}
@keyframes slideUp {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.animate-fade { animation: fadeIn 0.2s ease; }
.animate-slide { animation: slideUp 0.2s ease; }

/* --- Form Specific --- */
.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-4);
}

.checkbox-group {
    display: flex;
    align-items: center;
    gap: var(--space-2);
}
.checkbox-group input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: var(--primary);
}

/* --- Status Indicators --- */
.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    display: inline-block;
}
.status-dot.online { background: var(--success); }
.status-dot.offline { background: var(--gray-400); }
.status-dot.busy { background: var(--warning); }

/* --- Avatar --- */
.avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--primary-light);
    color: var(--primary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.875rem;
}
.avatar-sm { width: 32px; height: 32px; font-size: 0.75rem; }
.avatar-lg { width: 48px; height: 48px; font-size: 1rem; }

/* --- Empty State --- */
.empty-state {
    text-align: center;
    padding: var(--space-8);
    color: var(--text-muted);
}
.empty-state svg {
    width: 64px;
    height: 64px;
    margin-bottom: var(--space-4);
    opacity: 0.5;
}

/* --- Performance --- */
.tab-content:not(.active) {
    content-visibility: hidden;
}