:root {
  --primary: #6366f1;
  --primary-hover: #4f46e5;
  --primary-light: #eef2ff;
  --success: #10b981;
  --success-light: #d1fae5;
  --warning: #f59e0b;
  --warning-light: #fef3c7;
  --danger: #ef4444;
  --danger-light: #fee2e2;
  --info: #3b82f6;
  --info-light: #dbeafe;

  --bg: #f8fafc;
  --bg-secondary: #f1f5f9;
  --surface: #ffffff;
  --surface-hover: #f8fafc;
  --border: #e2e8f0;
  --text: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md:
    0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg:
    0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl:
    0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --sidebar-width: 260px;
  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

body.dark {
  --bg: #0f172a;
  --bg-secondary: #1e293b;
  --surface: #1e293b;
  --surface-hover: #334155;
  --border: #334155;
  --text: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --primary-light: rgba(99, 102, 241, 0.15);
  --success-light: rgba(16, 185, 129, 0.15);
  --warning-light: rgba(245, 158, 11, 0.15);
  --danger-light: rgba(239, 68, 68, 0.15);
  --info-light: rgba(59, 130, 246, 0.15);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md:
    0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
  --shadow-lg:
    0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
}

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

html {
  font-size: 16px;
}

body {
  font-family:
    "Inter",
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  transition: var(--transition);
  -webkit-font-smoothing: antialiased;
}

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

/* ===== Floating Sidebar Toggle (mobile only) ===== */
.floating-toggle {
  display: none;
  position: fixed;
  top: 16px;
  left: 16px;
  z-index: 200;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-md);
}

.floating-toggle:hover {
  background: var(--surface-hover);
  color: var(--text);
  border-color: var(--text-muted);
}

.floating-toggle svg {
  width: 18px;
  height: 18px;
}

.icon-menu {
  display: none;
}

.icon-close {
  display: block;
}

.sidebar.collapsed + .floating-toggle .icon-menu {
  display: block;
}

.sidebar.collapsed + .floating-toggle .icon-close {
  display: none;
}

/* ===== Sidebar ===== */
.sidebar {
  width: var(--sidebar-width);
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  z-index: 100;
  transition: var(--transition);
}

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

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 20px 16px;
  border-bottom: 1px solid var(--border);
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: -0.02em;
}

.logo svg {
  width: 28px;
  height: 28px;
}

.sidebar-nav {
  flex: 1;
  padding: 16px 12px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  overflow-y: auto;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
  text-align: left;
  width: 100%;
}

.nav-item svg {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
}

.nav-item:hover {
  background: var(--surface-hover);
  color: var(--text);
}

.nav-item.active {
  background: var(--primary-light);
  color: var(--primary);
  font-weight: 600;
}

.nav-count {
  margin-left: auto;
  background: var(--bg-secondary);
  color: var(--text-secondary);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 999px;
  min-width: 24px;
  text-align: center;
}

.nav-item.active .nav-count {
  background: var(--primary);
  color: #fff;
}

.sidebar-footer {
  padding: 16px;
  border-top: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.storage-info {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
}

.storage-info svg {
  width: 20px;
  height: 20px;
  color: var(--text-muted);
  flex-shrink: 0;
}

.storage-info div {
  display: flex;
  flex-direction: column;
}

.storage-label {
  font-size: 0.7rem;
  color: var(--text-muted);
  font-weight: 500;
}

.storage-value {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.theme-toggle {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 500;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
}

.theme-toggle:hover {
  background: var(--surface-hover);
  color: var(--text);
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
}

.icon-sun {
  display: none;
}

body.dark .icon-sun {
  display: block;
}

body.dark .icon-moon {
  display: none;
}

/* ===== Main Content ===== */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  padding: 24px 32px 40px;
  max-width: 1200px;
  transition: var(--transition);
}

.sidebar.collapsed ~ .main-content {
  margin-left: 0;
}

/* ===== Header ===== */
.main-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
  gap: 16px;
  flex-wrap: wrap;
}

.header-left h1 {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 4px;
}

.header-date {
  color: var(--text-muted);
  font-size: 0.9rem;
  font-weight: 400;
}

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

.search-box {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 8px 14px;
  transition: var(--transition);
  min-width: 240px;
}

.search-box:focus-within {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.search-box svg {
  width: 18px;
  height: 18px;
  color: var(--text-muted);
  flex-shrink: 0;
}

.search-box input {
  border: none;
  outline: none;
  background: transparent;
  color: var(--text);
  font-family: inherit;
  font-size: 0.9rem;
  width: 100%;
}

.search-box input::placeholder {
  color: var(--text-muted);
}

.icon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
}

.icon-btn:hover {
  background: var(--surface-hover);
  color: var(--text);
  border-color: var(--text-muted);
}

.icon-btn svg {
  width: 18px;
  height: 18px;
}

/* ===== Stats Grid ===== */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-bottom: 20px;
}

.stat-card {
  display: flex;
  align-items: center;
  gap: 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 16px;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
}

.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.stat-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  flex-shrink: 0;
}

.stat-icon svg {
  width: 22px;
  height: 22px;
}

.stat-total .stat-icon {
  background: var(--primary-light);
  color: var(--primary);
}

.stat-active .stat-icon {
  background: var(--info-light);
  color: var(--info);
}

.stat-done .stat-icon {
  background: var(--success-light);
  color: var(--success);
}

.stat-progress .stat-icon {
  background: var(--warning-light);
  color: var(--warning);
}

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

.stat-value {
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ===== Progress Bar ===== */
.progress-section {
  margin-bottom: 24px;
}

.progress-track {
  height: 8px;
  background: var(--bg-secondary);
  border-radius: 999px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--success));
  border-radius: 999px;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  min-width: 0;
}

/* ===== Add Task Form ===== */
.add-task-form {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 20px;
  margin-bottom: 24px;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.add-task-form:focus-within {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.input-group input {
  width: 100%;
  border: none;
  outline: none;
  background: transparent;
  font-family: inherit;
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--text);
  padding: 4px 0 12px;
}

.input-group input::placeholder {
  color: var(--text-muted);
  font-weight: 400;
}

.task-options {
  display: flex;
  align-items: flex-end;
  gap: 12px;
  flex-wrap: wrap;
}

.select-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
  flex: 1;
  min-width: 120px;
}

.select-group label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.select-group select,
.select-group input[type="date"] {
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--bg-secondary);
  color: var(--text);
  font-family: inherit;
  font-size: 0.85rem;
  outline: none;
  transition: var(--transition);
  cursor: pointer;
  width: 100%;
}

.select-group select:focus,
.select-group input[type="date"]:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.btn-add {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}

.btn-add:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-add:active {
  transform: translateY(0);
}

.btn-add svg {
  width: 18px;
  height: 18px;
}

/* ===== Task List ===== */
.task-list-container {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.list-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
  background: var(--bg-secondary);
}

.list-title {
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

.items-left {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.task-list {
  list-style: none;
  max-height: 500px;
  overflow-y: auto;
}

.task-list::-webkit-scrollbar {
  width: 6px;
}

.task-list::-webkit-scrollbar-track {
  background: transparent;
}

.task-list::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 999px;
}

.task-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 20px;
  border-bottom: 1px solid var(--border);
  transition: var(--transition);
  animation: slideIn 0.3s ease forwards;
  opacity: 0;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.task-item:last-child {
  border-bottom: none;
}

.task-item:hover {
  background: var(--surface-hover);
}

.task-item.completed .task-text {
  text-decoration: line-through;
  color: var(--text-muted);
}

.task-main {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  flex: 1;
  min-width: 0;
}

/* Checkbox */
.checkbox-wrapper {
  display: flex;
  align-items: center;
  cursor: pointer;
  flex-shrink: 0;
  margin-top: 2px;
}

.checkbox-wrapper input {
  display: none;
}

.checkmark {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border: 2px solid var(--border);
  border-radius: 6px;
  transition: var(--transition);
  color: transparent;
}

.checkmark svg {
  width: 14px;
  height: 14px;
}

.checkbox-wrapper input:checked + .checkmark {
  background: var(--success);
  border-color: var(--success);
  color: #fff;
}

.checkbox-wrapper:hover .checkmark {
  border-color: var(--success);
}

/* Task Content */
.task-content {
  flex: 1;
  min-width: 0;
}

.task-text-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 6px;
}

.task-text {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text);
  word-break: break-word;
  line-height: 1.4;
}

.important-badge {
  color: var(--warning);
  font-size: 1rem;
  flex-shrink: 0;
}

.task-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.category-badge,
.due-date,
.priority-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.75rem;
  font-weight: 500;
  padding: 3px 8px;
  border-radius: 999px;
}

.category-badge svg,
.due-date svg {
  width: 12px;
  height: 12px;
}

.category-work {
  background: var(--info-light);
  color: var(--info);
}

.category-personal {
  background: var(--primary-light);
  color: var(--primary);
}

.category-shopping {
  background: var(--warning-light);
  color: var(--warning);
}

.category-health {
  background: var(--success-light);
  color: var(--success);
}

.category-other {
  background: var(--bg-secondary);
  color: var(--text-secondary);
}

.due-date {
  background: var(--bg-secondary);
  color: var(--text-secondary);
}

.due-date.overdue {
  background: var(--danger-light);
  color: var(--danger);
}

.priority-badge {
  background: var(--bg-secondary);
  color: var(--text-secondary);
}

.priority-high {
  background: var(--danger-light);
  color: var(--danger);
}

.priority-medium {
  background: var(--warning-light);
  color: var(--warning);
}

.priority-low {
  background: var(--success-light);
  color: var(--success);
}

/* Task Actions */
.task-actions-group {
  display: flex;
  align-items: center;
  gap: 4px;
  opacity: 0;
  transition: var(--transition);
}

.task-item:hover .task-actions-group {
  opacity: 1;
}

.btn-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border: none;
  background: transparent;
  color: var(--text-muted);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
}

.btn-icon:hover {
  background: var(--bg-secondary);
  color: var(--text);
}

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

.btn-important.active {
  color: var(--warning);
}

.btn-important.active:hover {
  background: var(--warning-light);
}

.btn-delete:hover {
  background: var(--danger-light);
  color: var(--danger);
}

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

.empty-state svg {
  width: 48px;
  height: 48px;
  margin-bottom: 12px;
  opacity: 0.5;
}

.empty-state p {
  font-size: 0.9rem;
  font-weight: 500;
}

/* ===== Task Actions ===== */
.task-actions {
  display: flex;
  justify-content: flex-end;
  margin-top: 16px;
}

.btn-clear {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.btn-clear:hover {
  background: var(--danger-light);
  border-color: var(--danger);
  color: var(--danger);
}

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

/* ===== Developer Credit ===== */
.developer-credit {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-top: 32px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--text-muted);
}

.developer-credit a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--text-secondary);
  font-weight: 600;
  text-decoration: none;
  transition: var(--transition);
}

.developer-credit a:hover {
  color: var(--primary);
}

.developer-credit a svg {
  width: 18px;
  height: 18px;
  transition: var(--transition);
}

.developer-credit a:hover svg {
  transform: scale(1.1);
}

/* ===== Toast ===== */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--text);
  color: var(--bg);
  padding: 12px 24px;
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  z-index: 1000;
  opacity: 0;
  transition: var(--transition);
  pointer-events: none;
  max-width: 90vw;
  text-align: center;
}

.toast.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .main-content {
    margin-left: 0;
    padding: 16px;
  }

  .floating-toggle {
    display: flex;
    top: 12px;
    left: 12px;
  }

  .stats-grid {
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }

  .stat-card {
    padding: 12px;
  }

  .stat-icon {
    width: 36px;
    height: 36px;
  }

  .stat-value {
    font-size: 1.25rem;
  }

  .header-right {
    width: 100%;
  }

  .search-box {
    flex: 1;
    min-width: 0;
  }

  .task-options {
    flex-direction: column;
    align-items: stretch;
  }

  .select-group {
    min-width: 100%;
  }

  .btn-add {
    justify-content: center;
  }

  .task-actions-group {
    opacity: 1;
  }
}

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

  .main-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .header-right {
    flex-direction: column;
    align-items: stretch;
  }

  .search-box {
    width: 100%;
  }

  .icon-btn {
    align-self: flex-end;
  }
}