/* ============================================
   Time Tracker — Design System
   Dark Mode / Inter / Financial Dashboard
   ============================================ */

/* --- Reset & Base --- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

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

:root {
  /* Color Tokens */
  --bg-base: #020617;
  --bg-surface: #0F172A;
  --bg-card: #1E293B;
  --bg-card-hover: #253349;
  --bg-input: #0F172A;
  --bg-elevated: #334155;

  --text-primary: #F8FAFC;
  --text-secondary: #CBD5E1;
  --text-muted: #64748B;
  --text-placeholder: #475569;

  --accent-blue: #2563EB;
  --accent-blue-hover: #3B82F6;
  --accent-blue-muted: rgba(37, 99, 235, 0.15);

  --success: #22C55E;
  --success-muted: rgba(34, 197, 94, 0.15);
  --warning: #F59E0B;
  --warning-muted: rgba(245, 158, 11, 0.15);
  --danger: #EF4444;
  --danger-muted: rgba(239, 68, 68, 0.15);

  --border: #1E293B;
  --border-focus: #2563EB;
  --ring: rgba(37, 99, 235, 0.4);

  /* Typography */
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 2rem;

  /* Spacing (4px base) */
  --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;
  --space-10: 2.5rem;
  --space-12: 3rem;

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

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;

  /* Layout */
  --sidebar-width: 240px;
  --header-height: 56px;
  --max-content: 1200px;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font);
  background: var(--bg-base);
  color: var(--text-primary);
  line-height: 1.5;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --- Typography --- */
h1 { font-size: var(--text-3xl); font-weight: 700; letter-spacing: -0.025em; }
h2 { font-size: var(--text-2xl); font-weight: 600; letter-spacing: -0.015em; }
h3 { font-size: var(--text-xl); font-weight: 600; }
h4 { font-size: var(--text-lg); font-weight: 500; }

.text-muted { color: var(--text-muted); }
.text-secondary { color: var(--text-secondary); }
.text-success { color: var(--success); }
.text-warning { color: var(--warning); }
.text-danger { color: var(--danger); }

/* --- Layout: Shell --- */
.app-shell {
  display: flex;
  min-height: 100vh;
}

/* --- Sidebar --- */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 40;
  transition: transform var(--transition-base);
}

.sidebar-brand {
  padding: var(--space-5) var(--space-5);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: var(--space-3);
  height: var(--header-height);
}

.sidebar-brand .logo {
  width: 28px;
  height: 28px;
  background: var(--accent-blue);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: var(--text-sm);
}

.sidebar-brand span {
  font-weight: 600;
  font-size: var(--text-base);
}

.sidebar-nav {
  flex: 1;
  padding: var(--space-3) var(--space-3);
  overflow-y: auto;
}

.nav-section {
  margin-bottom: var(--space-4);
}

.nav-section-label {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: var(--space-2) var(--space-3);
  margin-bottom: var(--space-1);
}

.nav-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: var(--text-sm);
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  min-height: 40px;
}

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

.nav-item.active {
  background: var(--accent-blue-muted);
  color: var(--accent-blue-hover);
}

.nav-item svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.sidebar-footer {
  padding: var(--space-3);
  border-top: 1px solid var(--border);
}

/* --- Main Content --- */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  min-height: 100vh;
}

.page-header {
  padding: var(--space-6) var(--space-8);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  min-height: var(--header-height);
}

.page-header h1 {
  font-size: var(--text-2xl);
}

.page-body {
  padding: var(--space-6) var(--space-8);
  max-width: var(--max-content);
}

/* --- Cards --- */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  transition: border-color var(--transition-fast);
}

.card:hover {
  border-color: var(--bg-elevated);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-4);
}

.card-title {
  font-size: var(--text-base);
  font-weight: 600;
}

/* --- Stat Cards --- */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-4);
  margin-bottom: var(--space-6);
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
}

.stat-label {
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-bottom: var(--space-1);
}

.stat-value {
  font-size: var(--text-2xl);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.stat-change {
  font-size: var(--text-xs);
  margin-top: var(--space-1);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  font-family: var(--font);
  font-size: var(--text-sm);
  font-weight: 500;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all var(--transition-fast);
  min-height: 44px;
  text-decoration: none;
  white-space: nowrap;
}

.btn svg {
  width: 16px;
  height: 16px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

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

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

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

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

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
}

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

.btn-danger {
  background: var(--danger);
  color: white;
}

.btn-danger:hover {
  background: #DC2626;
}

.btn-success {
  background: var(--success);
  color: white;
}

.btn-sm {
  min-height: 36px;
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-xs);
}

.btn-lg {
  min-height: 52px;
  padding: var(--space-3) var(--space-6);
  font-size: var(--text-base);
}

/* --- Forms --- */
.form-group {
  margin-bottom: var(--space-5);
}

.form-label {
  display: block;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: var(--space-2);
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: var(--space-3) var(--space-3);
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: var(--font);
  font-size: var(--text-base);
  min-height: 44px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  outline: none;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--ring);
}

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

.form-select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748B' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 40px;
}

.form-textarea {
  min-height: 80px;
  resize: vertical;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-4);
}

.form-helper {
  font-size: var(--text-xs);
  color: var(--text-muted);
  margin-top: var(--space-1);
}

/* --- Tables --- */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
}

thead {
  background: var(--bg-surface);
}

th {
  text-align: left;
  padding: var(--space-3) var(--space-4);
  font-weight: 600;
  color: var(--text-muted);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}

td {
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
  vertical-align: middle;
}

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

tbody tr {
  transition: background var(--transition-fast);
}

tbody tr:hover {
  background: var(--bg-card-hover);
}

td.text-right, th.text-right {
  text-align: right;
}

td.font-mono {
  font-variant-numeric: tabular-nums;
}

/* --- Badges --- */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: var(--text-xs);
  font-weight: 500;
}

.badge-success {
  background: var(--success-muted);
  color: var(--success);
}

.badge-warning {
  background: var(--warning-muted);
  color: var(--warning);
}

.badge-danger {
  background: var(--danger-muted);
  color: var(--danger);
}

.badge-blue {
  background: var(--accent-blue-muted);
  color: var(--accent-blue-hover);
}

.badge-muted {
  background: rgba(100, 116, 139, 0.2);
  color: #94A3B8;
}

/* --- Checkboxes --- */
.checkbox-wrap {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  cursor: pointer;
  min-height: 44px;
}

.checkbox-wrap input[type="checkbox"] {
  width: 20px;
  height: 20px;
  accent-color: var(--accent-blue);
  cursor: pointer;
}

/* --- Toast --- */
.toast {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  background: var(--bg-card);
  border: 1px solid var(--success);
  border-radius: var(--radius-lg);
  padding: var(--space-3) var(--space-5);
  display: flex;
  align-items: center;
  gap: var(--space-3);
  box-shadow: var(--shadow-lg);
  z-index: 100;
  animation: slideIn 0.3s ease;
}

.toast-success { border-color: var(--success); }
.toast-warning { border-color: var(--warning); }

.toast svg {
  width: 20px;
  height: 20px;
  stroke: var(--success);
  fill: none;
  stroke-width: 2;
}

@keyframes slideIn {
  from { transform: translateY(20px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

/* --- Alert Banner --- */
.alert {
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-size: var(--text-sm);
  margin-bottom: var(--space-4);
}

.alert-warning {
  background: var(--warning-muted);
  border: 1px solid rgba(245, 158, 11, 0.3);
  color: var(--warning);
}

.alert-info {
  background: var(--accent-blue-muted);
  border: 1px solid rgba(37, 99, 235, 0.3);
  color: var(--accent-blue-hover);
}

.alert svg {
  width: 18px;
  height: 18px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  flex-shrink: 0;
}

/* --- Search --- */
.search-box {
  position: relative;
}

.search-box input {
  padding-left: 40px;
}

.search-box svg {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  stroke: var(--text-muted);
  fill: none;
  stroke-width: 2;
}

/* --- Tabs --- */
.tabs {
  display: flex;
  gap: var(--space-1);
  border-bottom: 1px solid var(--border);
  margin-bottom: var(--space-6);
}

.tab {
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-muted);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.tab:hover {
  color: var(--text-primary);
}

.tab.active {
  color: var(--accent-blue-hover);
  border-bottom-color: var(--accent-blue);
}

/* --- Divider --- */
.divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: var(--space-6) 0;
}

/* --- Empty State --- */
.empty-state {
  text-align: center;
  padding: var(--space-12) var(--space-6);
  color: var(--text-muted);
}

.empty-state svg {
  width: 48px;
  height: 48px;
  stroke: var(--text-muted);
  fill: none;
  stroke-width: 1.5;
  margin-bottom: var(--space-4);
}

.empty-state p {
  margin-bottom: var(--space-4);
}

/* --- Totals Row --- */
.totals-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-4) var(--space-5);
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  margin-top: var(--space-4);
}

.totals-row .label {
  font-weight: 600;
  color: var(--text-secondary);
}

.totals-row .amount {
  font-size: var(--text-xl);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

/* --- Filter Bar --- */
.filter-bar {
  display: flex;
  gap: var(--space-3);
  margin-bottom: var(--space-5);
  flex-wrap: wrap;
  align-items: center;
}

.filter-bar .form-select,
.filter-bar .form-input {
  width: auto;
  min-width: 160px;
}

/* --- Mobile Bottom Nav (shown on small screens) --- */
.mobile-nav {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--bg-surface);
  border-top: 1px solid var(--border);
  z-index: 50;
  padding: var(--space-1) 0;
  padding-bottom: env(safe-area-inset-bottom, 8px);
}

.mobile-nav-items {
  display: flex;
  justify-content: space-around;
}

.mobile-nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: var(--space-2);
  color: var(--text-muted);
  text-decoration: none;
  font-size: 10px;
  font-weight: 500;
  min-width: 64px;
  cursor: pointer;
}

.mobile-nav-item.active {
  color: var(--accent-blue-hover);
}

.mobile-nav-item svg {
  width: 22px;
  height: 22px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
}

/* --- Modal / Overlay --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  z-index: 60;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
}

.modal {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  width: 100%;
  max-width: 520px;
  max-height: 90vh;
  overflow-y: auto;
  padding: var(--space-6);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-6);
}

.modal-header h2 {
  font-size: var(--text-xl);
}

.modal-close {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: var(--space-2);
  min-height: 44px;
  min-width: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-close svg {
  width: 20px; height: 20px;
  stroke: currentColor; fill: none; stroke-width: 2;
}

.modal-footer {
  display: flex;
  gap: var(--space-3);
  justify-content: flex-end;
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  border-top: 1px solid var(--border);
}

/* --- Mobile helpers --- */
.hide-mobile { }
.mobile-only { display: none; }

/* --- Responsive --- */
@media (max-width: 768px) {
  html, body {
    overflow-x: hidden;
  }

  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
    min-width: 0;
    max-width: 100vw;
  }

  .page-header {
    padding: var(--space-4);
    flex-direction: column;
    align-items: flex-start;
  }

  .page-header h1 {
    font-size: var(--text-xl);
  }

  .page-body {
    padding: var(--space-4);
    padding-bottom: 100px; /* space for mobile nav */
  }

  .mobile-nav {
    display: block;
  }

  .hide-mobile { display: none !important; }
  .mobile-only { display: block; }

  .form-row {
    grid-template-columns: 1fr;
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .filter-bar {
    flex-direction: column;
    align-items: stretch;
  }

  .filter-bar .form-select,
  .filter-bar .form-input {
    width: 100%;
    min-width: 0;
  }

  /* --- Responsive Table → Card --- */
  .table-responsive thead { display: none; }

  .table-responsive,
  .table-responsive tbody,
  .table-responsive tr,
  .table-responsive td {
    display: block;
  }

  .table-responsive tr {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--space-3);
    margin-bottom: var(--space-2);
  }

  .table-responsive td {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-1) 0;
    border-bottom: none;
    font-size: var(--text-sm);
  }

  .table-responsive td::before {
    content: attr(data-label);
    font-weight: 500;
    color: var(--text-muted);
    font-size: var(--text-xs);
    text-transform: uppercase;
    letter-spacing: 0.03em;
    flex-shrink: 0;
    margin-right: var(--space-3);
  }

  .table-responsive td:first-child {
    font-weight: 600;
    font-size: var(--text-base);
    color: var(--text-primary);
    padding-bottom: var(--space-2);
    border-bottom: 1px solid var(--border);
    margin-bottom: var(--space-1);
  }

  .table-responsive td.text-right {
    text-align: right;
  }

  .table-responsive .table-wrap {
    border: none;
    border-radius: 0;
  }

  /* Billing page: client group headers */
  .client-group-header {
    flex-direction: column;
    gap: var(--space-1);
    align-items: flex-start;
  }

  .grand-total {
    flex-direction: column;
    gap: var(--space-2);
    text-align: center;
    padding: var(--space-4);
  }

  .grand-total .amount {
    font-size: var(--text-xl);
  }

  .export-bar {
    flex-direction: column;
    text-align: center;
  }

  .totals-row {
    flex-direction: column;
    gap: var(--space-2);
    text-align: center;
  }

  .month-selector .current {
    min-width: 120px;
    font-size: var(--text-base);
  }

  /* Modal: full-screen on mobile */
  .modal-overlay {
    align-items: flex-end;
    padding: 0;
  }

  .modal {
    max-width: 100%;
    max-height: 95vh;
    border-radius: var(--radius-xl) var(--radius-xl) 0 0;
    padding: var(--space-5);
  }
}

@media (max-width: 480px) {
  .stats-grid {
    grid-template-columns: 1fr;
  }
}

/* --- Sortable Table Headers --- */
th.sortable {
  cursor: pointer;
  user-select: none;
}
th.sortable:hover {
  color: var(--text-primary);
}
.sort-icon {
  font-size: var(--text-xs);
  color: var(--accent-blue-hover);
}

/* --- Utility --- */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.w-full { width: 100%; }
.text-right { text-align: right; }
.font-mono { font-variant-numeric: tabular-nums; }
.truncate { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }