:root {
  --bg-color: #f8fafc;
  --surface-color: #ffffff;
  --surface-border: #e2e8f0;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-light: #eef2ff;
  --accent: #06b6d4;
  --success: #10b981;
  --success-hover: #059669;
  --danger: #ef4444;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.08), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --transition: all 0.2s ease-in-out;

  /* Category colors */
  --cat-work: #4f46e5;
  --cat-fitness: #ef4444;
  --cat-study: #f59e0b;
  --cat-creative: #a855f7;
  --cat-personal: #10b981;
}

[data-theme="dark"] {
  --bg-color: #0b0f19;
  --surface-color: #151d2f;
  --surface-border: #222f46;
  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --primary: #6366f1;
  --primary-hover: #4f46e5;
  --primary-light: rgba(99, 102, 241, 0.15);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 6px 16px rgba(0, 0, 0, 0.5);

  --cat-work: #818cf8;
  --cat-fitness: #f87171;
  --cat-study: #fbbf24;
  --cat-creative: #c084fc;
  --cat-personal: #34d399;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  padding: 2.5rem 1rem;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.app-container {
  width: 100%;
  max-width: 860px;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* Header */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.brand-icon {
  font-size: 1.8rem;
  background: var(--primary-light);
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
}

.brand h1 {
  font-size: 1.65rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: 2px;
}

.theme-btn {
  background: var(--surface-color);
  border: 1px solid var(--surface-border);
  color: var(--text-main);
  border-radius: var(--radius-md);
  padding: 0.6rem 0.85rem;
  cursor: pointer;
  font-size: 1.2rem;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
}

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

/* Stats */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1rem;
}

.stat-card {
  background: var(--surface-color);
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-md);
  padding: 1.1rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  transition: var(--transition);
}

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

.stat-label {
  font-size: 0.8rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.stat-value {
  font-size: 1.65rem;
  font-weight: 700;
  color: var(--primary);
}

/* Category Distribution Card */
.distribution-card {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.dist-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
}

.dist-title {
  font-weight: 600;
  color: var(--text-main);
}

.dist-total {
  color: var(--text-muted);
  font-size: 0.8rem;
}

.progress-bar-container {
  display: flex;
  height: 12px;
  width: 100%;
  background: var(--bg-color);
  border-radius: 999px;
  overflow: hidden;
  border: 1px solid var(--surface-border);
}

.progress-segment {
  height: 100%;
  transition: width 0.3s ease;
}

.category-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  font-size: 0.78rem;
  color: var(--text-muted);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.legend-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  display: inline-block;
}

/* Timer Widget */
.timer-card {
  background: linear-gradient(135deg, var(--surface-color) 0%, var(--primary-light) 100%);
  border: 1px solid var(--primary);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  animation: slideDown 0.3s ease-out;
}

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

.timer-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.timer-badge {
  display: inline-block;
  background: var(--primary);
  color: #fff;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.15rem 0.5rem;
  border-radius: 12px;
  margin-bottom: 0.35rem;
}

.timer-title {
  font-size: 1.15rem;
  font-weight: 600;
}

.icon-btn {
  background: transparent;
  border: none;
  font-size: 1.4rem;
  line-height: 1;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

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

.timer-display-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
}

.timer-time {
  font-size: 3.5rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.03em;
  color: var(--primary);
}

.timer-progress-bg {
  width: 100%;
  height: 8px;
  background: rgba(0, 0, 0, 0.06);
  border-radius: 4px;
  overflow: hidden;
}

[data-theme="dark"] .timer-progress-bg {
  background: rgba(255, 255, 255, 0.1);
}

.timer-progress-fill {
  height: 100%;
  background: var(--primary);
  width: 100%;
  transition: width 1s linear;
}

.timer-controls {
  display: flex;
  justify-content: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.timer-btn {
  padding: 0.6rem 1.2rem;
  font-size: 0.9rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

.timer-btn-primary {
  background: var(--primary);
  color: #fff;
}
.timer-btn-primary:hover {
  background: var(--primary-hover);
}

.timer-btn-secondary {
  background: var(--surface-color);
  border: 1px solid var(--surface-border);
  color: var(--text-main);
}
.timer-btn-secondary:hover {
  background: var(--bg-color);
}

.timer-btn-success {
  background: var(--success);
  color: #fff;
}
.timer-btn-success:hover {
  background: var(--success-hover);
}

/* Main Cards */
.card {
  background: var(--surface-color);
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
}

.main-content {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* Form */
.form-card h2 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 1.1rem;
}

#activityForm {
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
}

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

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-main);
}

input[type="text"],
input[type="number"],
select {
  background: var(--bg-color);
  border: 1px solid var(--surface-border);
  color: var(--text-main);
  padding: 0.75rem 0.9rem;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  outline: none;
  transition: var(--transition);
}

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

.duration-chips {
  display: flex;
  gap: 0.4rem;
  margin-top: 0.3rem;
}

.preset-chip {
  background: var(--bg-color);
  border: 1px solid var(--surface-border);
  color: var(--text-muted);
  border-radius: 12px;
  padding: 0.2rem 0.5rem;
  font-size: 0.75rem;
  cursor: pointer;
  transition: var(--transition);
}

.preset-chip:hover {
  color: var(--primary);
  border-color: var(--primary);
}

.primary-btn {
  background: var(--primary);
  color: #ffffff;
  border: none;
  padding: 0.85rem 1.4rem;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

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

/* List Card */
.list-header {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

@media (min-width: 640px) {
  .list-header {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
  }
}

.list-header h2 {
  font-size: 1.15rem;
  font-weight: 600;
}

.controls-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
}

.search-box input {
  padding: 0.5rem 0.75rem;
  font-size: 0.85rem;
  border-radius: 20px;
}

.filter-group {
  display: flex;
  gap: 0.35rem;
  background: var(--bg-color);
  padding: 3px;
  border-radius: 20px;
  border: 1px solid var(--surface-border);
}

.filter-chip {
  background: transparent;
  border: none;
  padding: 0.35rem 0.8rem;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-muted);
  border-radius: 16px;
  cursor: pointer;
  transition: var(--transition);
}

.filter-chip.active {
  background: var(--surface-color);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

/* Activities */
.activity-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.activity-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.9rem 1.1rem;
  background: var(--bg-color);
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-md);
  transition: var(--transition);
  gap: 0.75rem;
}

.activity-item:hover {
  border-color: var(--primary-light);
  transform: translateX(2px);
}

.activity-item.completed {
  opacity: 0.65;
}

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

.activity-left {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  flex: 1;
  min-width: 0;
}

.checkbox-custom {
  appearance: none;
  width: 20px;
  height: 20px;
  border: 2px solid var(--text-muted);
  border-radius: 6px;
  cursor: pointer;
  display: grid;
  place-content: center;
  transition: var(--transition);
  flex-shrink: 0;
}

.checkbox-custom:checked {
  background-color: var(--success);
  border-color: var(--success);
}

.checkbox-custom:checked::before {
  content: "✓";
  font-size: 13px;
  color: #fff;
  font-weight: bold;
}

.activity-info {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  overflow: hidden;
}

.activity-title {
  font-size: 0.95rem;
  font-weight: 500;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.activity-meta {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.badge {
  padding: 0.15rem 0.5rem;
  border-radius: 12px;
  font-size: 0.72rem;
  font-weight: 600;
}

.badge-Work { background: #e0e7ff; color: #4338ca; }
.badge-Fitness { background: #fee2e2; color: #b91c1c; }
.badge-Study { background: #fef3c7; color: #b45309; }
.badge-Creative { background: #f3e8ff; color: #7e22ce; }
.badge-Personal { background: #dcfce7; color: #15803d; }

[data-theme="dark"] .badge-Work { background: rgba(99, 102, 241, 0.2); color: #a5b4fc; }
[data-theme="dark"] .badge-Fitness { background: rgba(239, 68, 68, 0.2); color: #fca5a5; }
[data-theme="dark"] .badge-Study { background: rgba(245, 158, 11, 0.2); color: #fcd34d; }
[data-theme="dark"] .badge-Creative { background: rgba(168, 85, 247, 0.2); color: #d8b4fe; }
[data-theme="dark"] .badge-Personal { background: rgba(34, 197, 94, 0.2); color: #86efac; }

.activity-right {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.focus-btn {
  background: var(--surface-color);
  border: 1px solid var(--surface-border);
  color: var(--primary);
  cursor: pointer;
  padding: 0.35rem 0.65rem;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 0.3rem;
  transition: var(--transition);
  white-space: nowrap;
}

.focus-btn:hover {
  background: var(--primary-light);
  border-color: var(--primary);
}

.delete-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0.4rem;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.delete-btn:hover {
  color: var(--danger);
  background: rgba(239, 68, 68, 0.1);
}

/* List Action Bar */
.list-actions-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px solid var(--surface-border);
  flex-wrap: wrap;
  gap: 0.5rem;
}

.action-buttons-right,
.action-buttons-left {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.text-action-btn {
  background: transparent;
  border: 1px solid var(--surface-border);
  color: var(--text-muted);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

.text-action-btn:hover {
  background: var(--bg-color);
  color: var(--text-main);
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 3rem 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.4rem;
}

.empty-icon {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
  opacity: 0.7;
}

.empty-title {
  font-weight: 600;
  font-size: 1rem;
}

.empty-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.hidden {
  display: none !important;
}

/* Footer */
.app-footer {
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  padding-bottom: 2rem;
}

/* Responsive adjustments */
@media (max-width: 600px) {
  .form-row {
    grid-template-columns: 1fr;
  }
  .controls-bar {
    width: 100%;
  }
  .search-box {
    width: 100%;
  }
  .search-box input {
    width: 100%;
  }
  .focus-btn span {
    display: none;
  }
  .timer-time {
    font-size: 2.75rem;
  }
}