:root {
  --primary: #5b6cf5;
  --primary-dark: #4753d8;
  --bg: #f2f3f7;
  --card: #ffffff;
  --text: #2a2d3a;
  --muted: #9aa0b0;
  --danger: #e05d5d;
  --radius: 12px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 48px 16px;
  background: var(--bg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--text);
}

.card {
  width: 100%;
  max-width: 520px;
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: 0 8px 30px rgba(30, 35, 70, 0.08);
  padding: 28px 24px;
}

h1 {
  margin: 0 0 20px;
  font-size: 24px;
  text-align: center;
}

/* 输入区 */
.todo-form {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
}

.todo-input {
  flex: 1;
  padding: 10px 14px;
  font-size: 15px;
  border: 1.5px solid #dfe2ec;
  border-radius: 8px;
  outline: none;
  transition: border-color 0.15s;
}

.todo-input:focus {
  border-color: var(--primary);
}

.add-btn {
  padding: 10px 18px;
  font-size: 15px;
  color: #fff;
  background: var(--primary);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.15s;
}

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

/* 筛选 */
.filters {
  display: flex;
  gap: 6px;
  margin-bottom: 12px;
}

.filter {
  padding: 5px 12px;
  font-size: 13px;
  color: var(--muted);
  background: transparent;
  border: 1px solid #dfe2ec;
  border-radius: 999px;
  cursor: pointer;
  transition: all 0.15s;
}

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

/* 列表 */
.todo-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.todo-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 4px;
  border-bottom: 1px solid #f0f1f6;
}

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

.todo-item input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--primary);
  cursor: pointer;
  flex-shrink: 0;
}

.todo-item .text {
  flex: 1;
  font-size: 15px;
  word-break: break-word;
}

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

.delete-btn {
  border: none;
  background: transparent;
  color: var(--muted);
  font-size: 16px;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
  opacity: 0;
  transition: all 0.15s;
}

.todo-item:hover .delete-btn {
  opacity: 1;
}

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

/* 空状态 */
.empty-hint {
  text-align: center;
  color: var(--muted);
  font-size: 14px;
  padding: 24px 0;
  margin: 0;
}

.empty-hint.hidden {
  display: none;
}

/* 状态栏 */
.status-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px solid #f0f1f6;
  font-size: 13px;
  color: var(--muted);
}

.clear-btn {
  border: none;
  background: transparent;
  color: var(--muted);
  font-size: 13px;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
  transition: all 0.15s;
}

.clear-btn:hover {
  color: var(--danger);
  background: #fdeeee;
}

@media (max-width: 480px) {
  body {
    padding: 24px 12px;
  }

  .delete-btn {
    opacity: 1;
  }
}