:root {
  --bg: #f3f4f6;
  --card: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --danger: #dc2626;
  --danger-hover: #b91c1c;
  --success: #16a34a;
  --border: #e5e7eb;
  --shadow: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -2px rgba(0,0,0,0.1);
}

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

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

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 16px;
}

header {
  text-align: center;
  margin-bottom: 24px;
}

header h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.025em;
}

.tagline {
  color: var(--muted);
  font-size: 0.95rem;
  margin-top: 4px;
}

.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 20px;
}

.stat {
  background: var(--card);
  border-radius: 12px;
  padding: 12px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-value {
  display: block;
  font-size: 1.25rem;
  font-weight: 700;
}

.stat-label {
  display: block;
  font-size: 0.75rem;
  color: var(--muted);
  margin-top: 2px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.add-task {
  display: flex;
  gap: 8px;
  background: var(--card);
  padding: 12px;
  border-radius: 12px;
  box-shadow: var(--shadow);
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.add-task input,
.add-task select {
  flex: 1 1 150px;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.95rem;
  background: var(--bg);
}

#task-date {
  flex: 0 1 140px;
  min-width: 140px;
}

#add-btn {
  padding: 8px 16px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.95rem;
}

#add-btn:hover {
  background: var(--accent-hover);
}

.filters {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 6px 14px;
  border: 1px solid var(--border);
  background: var(--card);
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.85rem;
  color: var(--muted);
}

.filter-btn.active {
  background: var(--text);
  color: #fff;
  border-color: var(--text);
}

.task-count {
  margin-left: auto;
  color: var(--muted);
  font-size: 0.85rem;
}

.actions {
  display: flex;
  gap: 8px;
  margin-bottom: 12px;
}

.actions button {
  padding: 6px 12px;
  border: 1px solid var(--border);
  background: var(--card);
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.85rem;
}

#clear-completed {
  color: var(--danger);
  border-color: var(--danger);
}

#clear-completed:hover {
  background: var(--danger);
  color: #fff;
}

#export-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.task-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.task-item {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--card);
  padding: 12px;
  border-radius: 10px;
  box-shadow: var(--shadow);
  border-left: 4px solid var(--accent);
}

.task-item.high {
  border-left-color: var(--danger);
}

.task-item.medium {
  border-left-color: #f59e0b;
}

.task-item.low {
  border-left-color: var(--success);
}

.task-item.completed {
  border-left-color: var(--muted);
  opacity: 0.75;
}

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

.task-check {
  width: 18px;
  height: 18px;
  cursor: pointer;
  accent-color: var(--accent);
}

.task-body {
  flex: 1;
  min-width: 0;
}

.task-title {
  font-size: 0.95rem;
  word-break: break-word;
}

.task-meta {
  font-size: 0.75rem;
  color: var(--muted);
  margin-top: 2px;
}

.task-btn {
  padding: 4px 8px;
  border: 1px solid var(--border);
  background: transparent;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.8rem;
  color: var(--muted);
}

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

.task-btn.delete:hover {
  color: var(--danger);
  border-color: var(--danger);
}

.empty-state {
  text-align: center;
  padding: 40px 16px;
  color: var(--muted);
}

footer {
  text-align: center;
  margin-top: 24px;
  color: var(--muted);
  font-size: 0.8rem;
}

@media (max-width: 480px) {
  .stats {
    grid-template-columns: repeat(2, 1fr);
  }
  .add-task {
    flex-direction: column;
  }
  #task-date {
    flex: 1 1 auto;
    min-width: unset;
  }
}