/* ── Custom Properties ────────────────────────────────────── */
:root {
  --color-bg: #f5f6fa;
  --color-surface: #ffffff;
  --color-primary: #4a6cf7;
  --color-primary-hover: #3a5be6;
  --color-danger: #e74c3c;
  --color-danger-hover: #c0392b;
  --color-overdue: #e74c3c;
  --color-overdue-bg: #fdecea;
  --color-today: #2e86de;
  --color-today-bg: #ebf5fb;
  --color-text: #2d3436;
  --color-text-secondary: #636e72;
  --color-border: #dfe6e9;
  --color-overlay: rgba(0, 0, 0, 0.45);
  --radius: 8px;
  --radius-lg: 12px;
  --shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
  --transition: 0.2s ease;
  --max-width: 720px;
}

/* ── Reset ────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
  min-height: 100vh;
}
input, button, select, textarea { font: inherit; }
button { cursor: pointer; }

.hidden { display: none !important; }

/* ── Login ────────────────────────────────────────────────── */
#login-section {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 1.5rem;
}
.login-container {
  text-align: center;
  max-width: 380px;
  width: 100%;
}
.logo {
  font-size: 2.2rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
}
.tagline {
  color: var(--color-text-secondary);
  margin-bottom: 2rem;
  font-size: 1.05rem;
}
.login-buttons {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.btn-oauth {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.25rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  font-size: 1rem;
  font-weight: 500;
  color: var(--color-text);
  text-decoration: none;
  transition: background var(--transition), box-shadow var(--transition);
  min-height: 48px;
}
.btn-oauth:hover {
  background: var(--color-bg);
  box-shadow: var(--shadow);
}
.btn-oauth.disabled {
  opacity: 0.45;
  cursor: not-allowed;
  pointer-events: none;
}

/* ── Top Bar ──────────────────────────────────────────────── */
.top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.25rem;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 50;
}
.top-bar-title {
  font-size: 1.25rem;
  font-weight: 700;
}

/* ── Settings Menu ────────────────────────────────────────── */
.settings-wrapper {
  position: relative;
}
.btn-icon {
  background: none;
  border: none;
  font-size: 1.3rem;
  cursor: pointer;
  padding: 0.3rem 0.5rem;
  border-radius: var(--radius);
  min-width: 44px;
  min-height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  transition: background var(--transition), color var(--transition);
}
.btn-icon:hover { background: var(--color-bg); color: var(--color-text); }
.settings-panel {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  width: min(280px, calc(100vw - 2rem));
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 200;
  padding: 0.75rem;
}
.settings-section {
  padding: 0.5rem 0;
}
.settings-section + .settings-section {
  border-top: 1px solid var(--color-border);
}
.settings-section-title {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}
.settings-hint {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  margin-bottom: 0.5rem;
}
.settings-full-btn {
  width: 100%;
  margin-top: 0.4rem;
  justify-content: center;
}
.settings-divider {
  border-top: 1px solid var(--color-border);
  margin: 0.25rem 0;
}
.settings-logout {
  width: 100%;
  justify-content: flex-start;
  padding-left: 0.25rem;
  color: var(--color-danger);
}
.settings-logout:hover { color: var(--color-danger-hover); }

/* ── Main Content ─────────────────────────────────────────── */
.main-content {
  max-width: min(100%, 1100px);
  margin: 0 auto;
  padding: 1.25rem 1rem 6rem;
}
.content-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  align-items: start;
}
.list-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}
.list-header h2 { font-size: 1.35rem; }

/* ── Tasks Column ─────────────────────────────────────────── */
.tasks-column {
  padding: 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}

/* ── Task List ────────────────────────────────────────────── */
.task-list {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}
.task-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.75rem 0.5rem 0.9rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-left: 4px solid transparent;
  border-radius: var(--radius);
  transition: box-shadow var(--transition), border-color var(--transition);
  cursor: pointer;
  min-height: 44px;
}
.task-row:hover {
  box-shadow: var(--shadow);
  border-color: var(--color-primary);
}
.task-row.overdue {
  border-left-color: var(--color-overdue);
  background: var(--color-overdue-bg);
}
.task-row.due-today {
  border-left-color: var(--color-today);
  background: var(--color-today-bg);
}
.task-row-title {
  flex: 1 1 0;
  min-width: 0;
  font-weight: 600;
  font-size: 0.95rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.task-row-meta {
  flex-shrink: 0;
  font-size: 0.78rem;
  color: var(--color-text-secondary);
  white-space: nowrap;
}
.task-row-actions {
  flex-shrink: 0;
  display: flex;
  gap: 0.25rem;
}
.btn-icon-sm {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  font-size: 0.95rem;
  cursor: pointer;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--transition), border-color var(--transition);
  flex-shrink: 0;
}
.btn-icon-sm:hover {
  background: var(--color-bg);
  border-color: var(--color-primary);
}
.badge {
  flex-shrink: 0;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.1rem 0.45rem;
  border-radius: 999px;
  white-space: nowrap;
}
.badge-overdue {
  background: var(--color-overdue);
  color: #fff;
}
.badge-today {
  background: var(--color-today);
  color: #fff;
}

/* ── Buttons ──────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  border: none;
  font-weight: 500;
  font-size: 0.9rem;
  transition: background var(--transition), opacity var(--transition);
  min-height: 44px;
  min-width: 44px;
}
.btn-primary {
  background: var(--color-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--color-primary-hover); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-secondary {
  background: var(--color-bg);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}
.btn-secondary:hover { background: var(--color-border); }
.btn-danger {
  background: var(--color-danger);
  color: #fff;
}
.btn-danger:hover { background: var(--color-danger-hover); }
.btn-text {
  background: none;
  color: var(--color-text-secondary);
  border: none;
}
.btn-text:hover { color: var(--color-text); }
.btn-small {
  padding: 0.3rem 0.65rem;
  font-size: 0.8rem;
  min-height: 36px;
  min-width: 36px;
  border-radius: 6px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
}
.btn-small:hover { background: var(--color-border); }
.btn-small.btn-primary {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}
.btn-small.btn-primary:hover { background: var(--color-primary-hover); }

/* ── FAB ──────────────────────────────────────────────────── */
.fab {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  font-size: 1.75rem;
  border: none;
  box-shadow: var(--shadow-lg);
  transition: transform var(--transition), background var(--transition);
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: center;
}
.fab:hover { background: var(--color-primary-hover); transform: scale(1.05); }

/* ── Modals ───────────────────────────────────────────────── */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--color-overlay);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 1rem;
  animation: fadeIn 0.15s ease;
}
.modal {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  width: 100%;
  max-width: 480px;
  max-height: 90vh;
  overflow-y: auto;
  animation: slideUp 0.2s ease;
}
.modal-small { max-width: 380px; }
.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--color-border);
}
.modal-header h2 { font-size: 1.15rem; }
.modal-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--color-text-secondary);
  line-height: 1;
  padding: 0.25rem;
  min-width: 44px;
  min-height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.modal-close:hover { color: var(--color-text); }
.modal-body { padding: 1.25rem; }

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

/* ── Forms ────────────────────────────────────────────────── */
.form-group {
  margin-bottom: 1rem;
  border: none;
}
.form-group label, .form-group legend {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 0.3rem;
  color: var(--color-text-secondary);
}
.form-group input[type="text"],
.form-group input[type="number"],
.form-group input[type="date"] {
  width: 100%;
  padding: 0.6rem 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 1rem;
  transition: border-color var(--transition);
  min-height: 44px;
}
.form-group input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(74, 108, 247, 0.15);
}
.form-error {
  display: block;
  color: var(--color-danger);
  font-size: 0.8rem;
  min-height: 1.2em;
  margin-top: 0.2rem;
}
.period-inputs {
  display: flex;
  gap: 1rem;
}
.period-inputs > div { flex: 1; }
.period-inputs input { width: 100%; }
.form-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  margin-top: 1.25rem;
}
.form-actions-right {
  display: flex;
  gap: 0.5rem;
  margin-left: auto;
}

/* ── Completion result ────────────────────────────────────── */
.complete-result {
  margin-top: 0.75rem;
  padding: 0.75rem;
  background: var(--color-today-bg);
  border-radius: var(--radius);
  text-align: center;
}

/* ── History ──────────────────────────────────────────────── */
.history-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.history-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 0.75rem;
  background: var(--color-bg);
  border-radius: var(--radius);
  font-size: 0.95rem;
}
.history-item-date { font-weight: 500; }
.history-item-created {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}
.history-empty {
  text-align: center;
  color: var(--color-text-secondary);
  padding: 2rem 0;
}

/* ── Pagination ───────────────────────────────────────────── */
.pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  margin-top: 1rem;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

/* ── Calendar ─────────────────────────────────────────────── */
.calendar-section {
  padding: 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}
.calendar-section h3 {
  font-size: 1.05rem;
  margin-bottom: 0.4rem;
}
.tz-picker {
  position: relative;
}
.timezone-input {
  width: 100%;
  padding: 0.3rem 0.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.8rem;
  background: var(--color-bg);
  color: var(--color-text);
}
.timezone-input:focus {
  outline: none;
  border-color: var(--color-primary);
}
.tz-dropdown {
  display: none;
  position: absolute;
  top: calc(100% + 2px);
  right: 0;
  min-width: 13rem;
  max-height: 200px;
  overflow-y: auto;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  z-index: 100;
}
.tz-dropdown.open { display: block; }
.tz-option {
  padding: 0.4rem 0.75rem;
  font-size: 0.8rem;
  cursor: pointer;
  white-space: nowrap;
}
.tz-option:hover { background: var(--color-bg); }
.calendar-hint {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-bottom: 0.75rem;
}
.calendar-url-display {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 0.75rem;
  background: var(--color-bg);
  border-radius: var(--radius);
  margin-bottom: 0.75rem;
  overflow: hidden;
}
.calendar-url-display code {
  flex: 1;
  min-width: 0;
  font-size: 0.8rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  color: var(--color-text-secondary);
}

/* ── Toast ────────────────────────────────────────────────── */
.toast {
  position: fixed;
  bottom: 1.5rem;
  left: 50%;
  transform: translateX(-50%);
  background: var(--color-text);
  color: #fff;
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius);
  font-size: 0.9rem;
  z-index: 200;
  box-shadow: var(--shadow-lg);
  animation: fadeIn 0.15s ease;
  max-width: 90vw;
  text-align: center;
}
.toast.toast-error { background: var(--color-danger); }

/* ── Loading / empty ──────────────────────────────────────── */
.loading-text {
  text-align: center;
  color: var(--color-text-secondary);
  padding: 2rem 0;
}
.empty-state {
  text-align: center;
  color: var(--color-text-secondary);
  padding: 3rem 1rem;
}
.empty-state p { margin-top: 0.5rem; font-size: 0.95rem; }

/* ── Toggle Switch ───────────────────────────────────────── */
.toggle-label {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.9rem;
  cursor: pointer;
  user-select: none;
  gap: 0.75rem;
}
.toggle-switch { position: relative; display: inline-block; flex-shrink: 0; }
.toggle-switch input { opacity: 0; width: 0; height: 0; position: absolute; }
.toggle-track {
  display: block;
  width: 38px;
  height: 22px;
  background: var(--color-border);
  border-radius: 11px;
  transition: background var(--transition);
  position: relative;
}
.toggle-track::after {
  content: '';
  position: absolute;
  top: 3px;
  left: 3px;
  width: 16px;
  height: 16px;
  background: #fff;
  border-radius: 50%;
  transition: transform var(--transition);
}
.toggle-switch input:checked + .toggle-track { background: var(--color-primary); }
.toggle-switch input:checked + .toggle-track::after { transform: translateX(16px); }

/* ── Dark Mode ───────────────────────────────────────────── */
[data-theme="dark"] {
  color-scheme: dark;
  --color-bg: #1a1d2e;
  --color-surface: #252840;
  --color-primary: #6b8cfa;
  --color-primary-hover: #5a7af0;
  --color-danger: #e74c3c;
  --color-danger-hover: #c0392b;
  --color-overdue: #ff6b6b;
  --color-overdue-bg: #3d1a1a;
  --color-today: #5dade2;
  --color-today-bg: #1a2a3d;
  --color-text: #e8eaf0;
  --color-text-secondary: #9b9eb5;
  --color-border: #3a3d5c;
  --color-overlay: rgba(0, 0, 0, 0.65);
  --shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.45);
}

/* ── Desktop (≥ 768px) ────────────────────────────────────── */
@media (min-width: 768px) {
  .main-content { padding: 2rem 1.5rem 4rem; }
  .content-grid { grid-template-columns: 1fr 420px; }
  .fab { display: none; }
  #btn-add-task { display: inline-flex; }
}

/* ── Mobile (< 768px) ─────────────────────────────────────── */
@media (max-width: 767px) {
  #btn-add-task { display: none; }
  .modal { max-height: 95vh; border-radius: var(--radius-lg) var(--radius-lg) 0 0; align-self: flex-end; }
  .modal-overlay { align-items: flex-end; padding: 0; }
  .task-row-meta { display: none; }
}