/* ============================================
   L-MATH 乐学数学 - 单元页面共享样式
   用于 grades/gradeX/unitN.html 页面
   ============================================ */

/* 页面背景 */
body {
  background: linear-gradient(180deg, #FFF5EB 0%, #FFF 100%);
  min-height: 100vh;
}

/* 单元头部 */
.unit-header {
  color: white;
  padding: 48px 24px 32px;
  text-align: center;
}

.unit-header .back-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: white;
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 20px;
  opacity: 0.9;
  text-decoration: none;
}

.unit-header .back-btn:hover {
  opacity: 1;
  text-decoration: underline;
}

.unit-header h1 {
  font-family: 'ZCOOL KuaiLe', cursive;
  font-size: 1.8rem;
  margin-bottom: 8px;
}

.unit-header .unit-desc {
  opacity: 0.9;
  font-size: 0.95rem;
}

/* 单元内容区 */
.unit-content {
  max-width: 800px;
  margin: 0 auto;
  padding: 32px 24px 64px;
}

/* 课程卡片 */
.lesson-card {
  background: white;
  border-radius: 20px;
  padding: 28px;
  margin-bottom: 24px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
  border: 1px solid #f0f0f0;
}

/* 课程标题 */
.lesson-title {
  font-family: 'ZCOOL KuaiLe', cursive;
  font-size: 1.3rem;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.lesson-title .num {
  width: 32px;
  height: 32px;
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  font-weight: 700;
}

/* 学习框 */
.learn-box {
  border-radius: 12px;
  padding: 16px 20px;
  margin-bottom: 16px;
  border-left: 4px solid;
}

.learn-box h4 {
  font-size: 0.95rem;
  margin-bottom: 8px;
}

.learn-box ul {
  padding-left: 20px;
  color: #555;
  font-size: 0.9rem;
  line-height: 1.8;
}

/* 示例框 */
.example-box {
  background: #F8F9FA;
  border-radius: 12px;
  padding: 20px;
  margin: 16px 0;
}

.example-box h4 {
  font-size: 0.9rem;
  color: #888;
  margin-bottom: 12px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

/* 计算步骤 */
.calc-step {
  background: white;
  border-radius: 12px;
  padding: 16px 20px;
  margin: 12px 0;
}

.calc-step .formula {
  font-size: 1.5rem;
  font-weight: 700;
  text-align: center;
  margin: 8px 0;
  font-family: monospace;
}

.calc-step p {
  font-size: 0.9rem;
  color: #333;
  line-height: 1.8;
}

/* 步骤框 */
.step-box {
  background: white;
  border-radius: 12px;
  padding: 16px 20px;
  margin: 12px 0;
  border: 2px solid #FFF5F5;
}

.step-title {
  font-weight: 700;
  margin-bottom: 8px;
  font-size: 0.95rem;
}

/* 计算演示 */
.calc-demo {
  font-family: monospace;
  font-size: 1.3rem;
  padding: 16px;
  border-radius: 12px;
  text-align: center;
  margin: 16px 0;
}

.calc-item {
  border-radius: 12px;
  padding: 12px 20px;
  font-size: 1.3rem;
  font-weight: 700;
}

.calc-item .op {
  color: #888;
  font-size: 1.1rem;
}

.calc-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 15px;
  font-size: 2rem;
  flex-wrap: wrap;
}

.calc-operator {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  color: white;
}

/* 图片行 */
.pic-row {
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
  font-size: 3rem;
  margin: 16px 0;
}

/* 数字卡片 */
.number-row {
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
  font-size: 2.5rem;
  margin: 20px 0;
}

.number-card {
  background: white;
  border-radius: 16px;
  padding: 20px;
  text-align: center;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  min-width: 100px;
}

.number-card .digit {
  font-size: 3rem;
  font-weight: 700;
  font-family: 'ZCOOL KuaiLe', cursive;
}

.number-card .objects {
  font-size: 1.5rem;
  margin-top: 10px;
}

/* 练习框 */
.practice-box {
  border-radius: 16px;
  padding: 24px;
  border: 2px solid;
}

.practice-box h3 {
  font-family: 'ZCOOL KuaiLe', cursive;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

/* 题目 */
.question {
  background: white;
  border-radius: 12px;
  padding: 16px 20px;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.q-num {
  width: 28px;
  height: 28px;
  color: white;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
  flex-shrink: 0;
}

.q-text {
  font-size: 0.95rem;
  color: #333;
}

/* 检查按钮 */
.check-btn {
  display: block;
  width: 100%;
  max-width: 200px;
  margin: 20px auto 0;
  padding: 12px 24px;
  color: white;
  border: none;
  border-radius: 999px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.3s;
}

.check-btn:hover {
  transform: scale(1.02);
}

/* 面包屑导航 */
.breadcrumb {
  background: white;
  padding: 16px 24px;
  border-radius: 12px;
  margin-bottom: 24px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.breadcrumb-list {
  display: flex;
  align-items: center;
  gap: 8px;
  list-style: none;
  flex-wrap: wrap;
}

.breadcrumb-item a {
  text-decoration: none;
}

.breadcrumb-item a:hover {
  text-decoration: underline;
}

.breadcrumb-item span {
  color: #888;
}

.breadcrumb-separator {
  color: #ccc;
}

/* 复习网格（六年级总复习等） */
.review-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin: 16px 0;
}

.review-card {
  border-radius: 16px;
  padding: 20px;
  border: 2px solid;
}

.review-card h4 {
  font-size: 1.1rem;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.review-card ul {
  padding-left: 16px;
  color: #555;
  font-size: 0.85rem;
  line-height: 1.9;
}

/* 公式区 */
.formula-section {
  background: #F8F9FA;
  border-radius: 16px;
  padding: 24px;
  margin: 16px 0;
}

.formula-section h4 {
  font-size: 1.1rem;
  margin-bottom: 16px;
}

.formula-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
}

.formula-item {
  background: white;
  border-radius: 12px;
  padding: 16px;
  text-align: center;
  border: 1px solid #E9ECEF;
}

.formula-item .name {
  font-size: 0.85rem;
  color: #888;
  margin-bottom: 8px;
}

.formula-item .math {
  font-size: 1.1rem;
  font-weight: 700;
  font-family: monospace;
}

/* 提示框 */
.tip-box {
  border-radius: 12px;
  padding: 20px;
  border-left: 4px solid #FFD43B;
  margin: 16px 0;
}

.tip-box h4 {
  margin-bottom: 8px;
}

.tip-box p {
  color: #666;
  font-size: 0.9rem;
  line-height: 1.8;
}

/* 检查清单 */
.checklist {
  background: white;
  border-radius: 12px;
  padding: 20px;
  margin: 16px 0;
}

.checklist h4 {
  margin-bottom: 12px;
}

.checklist-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 0;
  border-bottom: 1px solid #f0f0f0;
}

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

.check-icon {
  width: 24px;
  height: 24px;
  border: 2px solid;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
}

/* 植树问题专用 */
.tree-demo {
  background: white;
  border-radius: 12px;
  padding: 24px;
  margin: 12px 0;
  border: 2px solid #E9ECEF;
  text-align: center;
}

.tree-row {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  margin: 16px 0;
  flex-wrap: wrap;
}

.tree-icon {
  font-size: 2rem;
}

.gap-icon {
  font-size: 1.5rem;
  font-weight: bold;
}

.formula-box {
  border-radius: 12px;
  padding: 20px;
  margin: 16px 0;
  text-align: center;
}

.formula-box .formula {
  font-size: 1.3rem;
  font-weight: 700;
  margin: 8px 0;
}

.formula-box .desc {
  font-size: 0.9rem;
  color: #666;
  margin-top: 8px;
}

.case-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin: 16px 0;
}

.case-card {
  background: white;
  border-radius: 12px;
  padding: 20px;
  border: 2px solid #E9ECEF;
  text-align: center;
}

.case-card h5 {
  font-size: 1rem;
  margin-bottom: 8px;
}

.case-card p {
  font-size: 0.85rem;
  color: #666;
}

/* ============================================
   年级主题色 - 通过 data-grade 属性自动适配
   在 <body> 标签上添加 data-grade="N" 即可
   ============================================ */

/* 一年级 */
[data-grade="1"] .unit-header { background: linear-gradient(135deg, #FF6B6B 0%, #FFA8A8 100%); }
[data-grade="1"] .lesson-title { color: #FF6B6B; }
[data-grade="1"] .lesson-title .num { background: #FF6B6B; }
[data-grade="1"] .learn-box { background: #FFF5F5; border-left-color: #FF6B6B; }
[data-grade="1"] .learn-box h4 { color: #FF6B6B; }
[data-grade="1"] .practice-box { background: linear-gradient(135deg, #E8F8F5 0%, #D6FFF0 100%); border-color: #69DB7C; }
[data-grade="1"] .practice-box h3 { color: #2D8A4E; }
[data-grade="1"] .q-num { background: #69DB7C; }
[data-grade="1"] .breadcrumb-item a { color: #FF6B6B; }
[data-grade="1"] .check-btn { background: #69DB7C; }
[data-grade="1"] .review-card { background: #FFF5F5; border-color: #FFA8A8; }
[data-grade="1"] .review-card h4 { color: #FF6B6B; }
[data-grade="1"] .formula-box { background: #FFF5F5; }
[data-grade="1"] .calc-operator { background: #FF6B6B; }
[data-grade="1"] .tip-box { background: #FFF9E6; }

/* 二年级 */
[data-grade="2"] .unit-header { background: linear-gradient(135deg, #FFA94D 0%, #FFD8A8 100%); }
[data-grade="2"] .lesson-title { color: #FFA94D; }
[data-grade="2"] .lesson-title .num { background: #FFA94D; }
[data-grade="2"] .learn-box { background: #FFF9E6; border-left-color: #FFA94D; }
[data-grade="2"] .learn-box h4 { color: #FFA94D; }
[data-grade="2"] .practice-box { background: linear-gradient(135deg, #E8F4FF 0%, #D6EEFF 100%); border-color: #4DABF7; }
[data-grade="2"] .practice-box h3 { color: #2b7ed9; }
[data-grade="2"] .q-num { background: #4DABF7; }
[data-grade="2"] .breadcrumb-item a { color: #FFA94D; }
[data-grade="2"] .check-btn { background: #4DABF7; }
[data-grade="2"] .review-card { background: #FFF9E6; border-color: #FFD8A8; }
[data-grade="2"] .review-card h4 { color: #FFA94D; }
[data-grade="2"] .formula-box { background: #FFF9E6; }
[data-grade="2"] .calc-operator { background: #FFA94D; }
[data-grade="2"] .tip-box { background: #FFF5F5; }

/* 三年级 */
[data-grade="3"] .unit-header { background: linear-gradient(135deg, #FFD93D 0%, #FFE8A0 100%); }
[data-grade="3"] .lesson-title { color: #E8B400; }
[data-grade="3"] .lesson-title .num { background: #FFD93D; }
[data-grade="3"] .learn-box { background: #FFF9DB; border-left-color: #FFD93D; }
[data-grade="3"] .learn-box h4 { color: #E8B400; }
[data-grade="3"] .practice-box { background: linear-gradient(135deg, #F3F0FF 0%, #E0CCFF 100%); border-color: #9775FA; }
[data-grade="3"] .practice-box h3 { color: #7C3AED; }
[data-grade="3"] .q-num { background: #9775FA; }
[data-grade="3"] .breadcrumb-item a { color: #E8B400; }
[data-grade="3"] .check-btn { background: #9775FA; }
[data-grade="3"] .review-card { background: #FFF9DB; border-color: #FFE8A0; }
[data-grade="3"] .review-card h4 { color: #E8B400; }
[data-grade="3"] .formula-box { background: #FFF9DB; }
[data-grade="3"] .calc-operator { background: #FFD93D; }
[data-grade="3"] .tip-box { background: #E8F4FF; }

/* 四年级 */
[data-grade="4"] .unit-header { background: linear-gradient(135deg, #69DB7C 0%, #8CE99A 100%); }
[data-grade="4"] .lesson-title { color: #2D8A4E; }
[data-grade="4"] .lesson-title .num { background: #69DB7C; }
[data-grade="4"] .learn-box { background: #E8F8F5; border-left-color: #69DB7C; }
[data-grade="4"] .learn-box h4 { color: #2D8A4E; }
[data-grade="4"] .practice-box { background: linear-gradient(135deg, #FFF4EE 0%, #FFE8D6 100%); border-color: #FF6B35; }
[data-grade="4"] .practice-box h3 { color: #E85A25; }
[data-grade="4"] .q-num { background: #FF6B35; }
[data-grade="4"] .breadcrumb-item a { color: #2D8A4E; }
[data-grade="4"] .check-btn { background: #FF6B35; }
[data-grade="4"] .review-card { background: #E8F8F5; border-color: #8CE99A; }
[data-grade="4"] .review-card h4 { color: #2D8A4E; }
[data-grade="4"] .formula-box { background: #E8F8F5; }
[data-grade="4"] .calc-operator { background: #69DB7C; }
[data-grade="4"] .tip-box { background: #FFF9E6; }

/* 五年级 */
[data-grade="5"] .unit-header { background: linear-gradient(135deg, #4DABF7 0%, #74C0FC 100%); }
[data-grade="5"] .lesson-title { color: #2b7ed9; }
[data-grade="5"] .lesson-title .num { background: #4DABF7; }
[data-grade="5"] .learn-box { background: #E8F4FF; border-left-color: #4DABF7; }
[data-grade="5"] .learn-box h4 { color: #2b7ed9; }
[data-grade="5"] .practice-box { background: linear-gradient(135deg, #FFF5F5 0%, #FFE0E0 100%); border-color: #FF6B6B; }
[data-grade="5"] .practice-box h3 { color: #E03131; }
[data-grade="5"] .q-num { background: #FF6B6B; }
[data-grade="5"] .breadcrumb-item a { color: #2b7ed9; }
[data-grade="5"] .check-btn { background: #FF6B6B; }
[data-grade="5"] .review-card { background: #E8F4FF; border-color: #74C0FC; }
[data-grade="5"] .review-card h4 { color: #2b7ed9; }
[data-grade="5"] .formula-box { background: #E8F4FF; }
[data-grade="5"] .calc-operator { background: #4DABF7; }
[data-grade="5"] .tip-box { background: #FFF5F5; }

/* 六年级 */
[data-grade="6"] .unit-header { background: linear-gradient(135deg, #9775FA 0%, #B197FC 100%); }
[data-grade="6"] .lesson-title { color: #7C3AED; }
[data-grade="6"] .lesson-title .num { background: #9775FA; }
[data-grade="6"] .learn-box { background: #F3F0FF; border-left-color: #9775FA; }
[data-grade="6"] .learn-box h4 { color: #7C3AED; }
[data-grade="6"] .practice-box { background: linear-gradient(135deg, #FFF4EE 0%, #FFE8D6 100%); border-color: #FF6B35; }
[data-grade="6"] .practice-box h3 { color: #E85A25; }
[data-grade="6"] .q-num { background: #FF6B35; }
[data-grade="6"] .breadcrumb-item a { color: #7C3AED; }
[data-grade="6"] .check-btn { background: #FF6B35; }
[data-grade="6"] .review-card { background: #F3F0FF; border-color: #B197FC; }
[data-grade="6"] .review-card h4 { color: #7C3AED; }
[data-grade="6"] .formula-box { background: #F3F0FF; }
[data-grade="6"] .calc-operator { background: #9775FA; }
[data-grade="6"] .tip-box { background: #E8F4FF; }

/* 通用导航栏间距 */
body[data-grade] { padding-top: 64px; }
body[data-grade] .unit-header { margin-top: -64px; padding-top: calc(48px + 64px); }