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

:root {
  --color-bg: #f5f7fa;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-text: #1a202c;
  --color-text-muted: #718096;
  --color-primary: #4f46e5;
  --color-primary-hover: #4338ca;
  --color-danger: #e53e3e;
  --color-danger-hover: #c53030;
  --color-high: #e53e3e;
  --color-medium: #dd6b20;
  --color-low: #38a169;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  font-size: 15px;
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 760px;
  margin: 0 auto;
  padding: 24px 16px 64px;
}

header {
  margin-bottom: 24px;
}

header h1 {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--color-primary);
}

/* Form */
.add-task {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}

.add-task h2 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 14px;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
  flex: 1;
}

.form-group label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-muted);
}

.form-row {
  display: flex;
  gap: 12px;
  margin: 12px 0;
  flex-wrap: wrap;
}

input[type="text"],
input[type="date"],
select {
  width: 100%;
  padding: 9px 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.95rem;
  color: var(--color-text);
  background: var(--color-bg);
  outline: none;
  transition: border-color 0.15s;
}

input[type="text"]:focus,
input[type="date"]:focus,
select:focus {
  border-color: var(--color-primary);
  background: #fff;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 9px 20px;
  border: none;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, opacity 0.15s;
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  width: 100%;
  margin-top: 4px;
}

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

/* Controls */
.controls {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}

.filters {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

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

.filter-group label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* Task list */
.task-list-section {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.list-header {
  padding: 12px 20px;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.85rem;
  color: var(--color-text-muted);
  font-weight: 500;
}

#task-list {
  list-style: none;
}

.task-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 14px 20px;
  border-bottom: 1px solid var(--color-border);
  transition: background 0.1s;
}

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

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

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

.task-item.done .task-meta {
  opacity: 0.5;
}

.task-checkbox {
  width: 18px;
  height: 18px;
  margin-top: 3px;
  flex-shrink: 0;
  cursor: pointer;
  accent-color: var(--color-primary);
}

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

.task-title {
  font-weight: 500;
  word-break: break-word;
  margin-bottom: 5px;
}

.task-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  font-size: 0.78rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px 8px;
  border-radius: 100px;
  font-weight: 600;
  font-size: 0.72rem;
  letter-spacing: 0.03em;
}

.priority-high   { background: #fff5f5; color: var(--color-high); }
.priority-medium { background: #fffaf0; color: var(--color-medium); }
.priority-low    { background: #f0fff4; color: var(--color-low); }

.category-badge {
  background: #eef2ff;
  color: #4338ca;
}

.due-badge {
  color: var(--color-text-muted);
}

.due-badge.overdue {
  color: var(--color-danger);
  font-weight: 700;
}

.task-actions {
  flex-shrink: 0;
}

.btn-delete {
  background: none;
  border: none;
  padding: 4px 6px;
  cursor: pointer;
  color: var(--color-text-muted);
  border-radius: 4px;
  font-size: 1rem;
  line-height: 1;
  transition: color 0.15s, background 0.15s;
}

.btn-delete:hover {
  color: var(--color-danger);
  background: #fff5f5;
}

.empty-message {
  text-align: center;
  padding: 48px 20px;
  color: var(--color-text-muted);
}

.hidden {
  display: none;
}

/* Responsive */
@media (max-width: 480px) {
  header h1 {
    font-size: 1.4rem;
  }

  .form-row {
    flex-direction: column;
  }

  .filter-group {
    min-width: calc(50% - 6px);
  }

  .task-item {
    padding: 12px 14px;
  }
}