:root {
  /* 主题色 & 基础色板 */
  --color-bg: #f9fafb;
  --color-header-start: #1d4ed8;
  --color-header-end: #2563eb;
  --color-footer-bg: #111827;
  --color-footer-text: #d1d5db;
  --color-divider: #e5e7eb;
  --color-btn-default-bg: rgba(255,255,255,0.2);
  --color-btn-hover-bg: rgba(255,255,255,0.3);
  --color-btn-active-bg: #ffffff;
  --color-btn-active-text: #1d4ed8;
  --color-btn-hover-text: #ffffff;
  --color-sub-bg: #fdfdfd;
  --color-sub-hover-bg: #f3f4f6;
  --color-sub-active-border: #10b981;
  --color-card-bg: #ffffff;
  --color-card-shadow: rgba(0,0,0,0.1);
  --color-note-border: #e5e7eb;
  --font-family-base: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

/* —— 全局 —— */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
}
body {
  display: flex;
  flex-direction: column;
  font-family: var(--font-family-base);
  background-color: var(--color-bg);
  color: var(--color-btn-active-text);
  min-height: 100vh;
}

/* —— Header —— */
.header {
  padding: 1rem 2rem;
  background: linear-gradient(90deg, var(--color-header-start), var(--color-header-end));
  color: #fff;
  box-shadow: 0 2px 6px rgba(0,0,0,0.15);
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.header-brand {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.platform-title {
  font-size: clamp(1.75rem, 5vw, 2.5rem);
  font-weight: bold;
  white-space: nowrap;
  text-align: left;
  margin-right: 1rem;
}

.header-logo {
  height: 2.5rem;
  width: auto;
  object-fit: contain;
}

.title-separator {
  border: none;
  border-top: 2px solid var(--color-divider);
  width: 100%;
  margin-bottom: 0.75rem;
}

/* —— 一级菜单 —— */
.category-nav {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  overflow-x: auto;
  padding: 0.25rem 0;
  -webkit-overflow-scrolling: touch;
  margin-bottom: 0.5rem;
}

.category-nav::-webkit-scrollbar {
  display: none;
}

.category-nav .btn-category {
  position: relative;
  background-color: var(--color-btn-default-bg);
  color: var(--color-btn-hover-text);
  border: none;
  border-radius: 0.375rem;
  padding: 0.5rem 1.5rem;
  min-width: 6rem;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background-color .2s, color .2s, transform .2s;
}

.category-nav .btn-category:hover {
  background-color: var(--color-btn-hover-bg);
  color: var(--color-btn-hover-text);
  transform: translateY(-2px);
}

.category-nav .btn-category.active {
  background-color: var(--color-btn-active-bg);
  color: var(--color-btn-active-text);
  box-shadow: 0 2px 6px rgba(0,0,0,0.15);
}

.category-nav .btn-category::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 100%;
  height: 3px;
  background: var(--color-btn-active-text);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform .3s;
}

.category-nav .btn-category:hover::after,
.category-nav .btn-category.active::after {
  transform: scaleX(1);
}

/* —— Main —— */
.main {
  display: flex;
  padding: 1rem 2rem;
  flex: 1;
  overflow: hidden;
  flex-direction: row;  /* 横向布局：左侧菜单 + 右侧图表 */
  width: 100%;
}

/* —— 左侧 Submenu —— */
.submenu {
  width: 280px;
  background-color: var(--color-card-bg);
  border-radius: 0.5rem;
  box-shadow: 0 1px 3px var(--color-card-shadow);
  padding: 1rem;
  margin-right: 1rem;
  overflow-y: auto;
}

.submenu-item {
  display: flex;
  align-items: center;
  background-color: var(--color-sub-bg);
  border-radius: 0.375rem;
  border-left: 4px solid transparent;
  margin-bottom: 0.25rem;
  padding: 0.5rem;
  transition: border-color .2s, background-color .2s;
}

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

.submenu-item input[type="checkbox"] {
  margin-right: 0.5rem;
  cursor: pointer;
}

.submenu-item input[type="checkbox"]:checked + label {
  font-weight: 600;
}

.submenu-item input[type="checkbox"]:checked ~ label {
  border-left: 4px solid var(--color-sub-active-border);
}

.submenu-item label {
  flex: 1;
  cursor: pointer;
  transition: color .2s;
}

/* —— 右侧 Chart Area —— */
.chart-area {
  flex: 1;
  display: grid;
  grid-template-rows: 1fr auto;  /* 图表与备注各占一行 */
  overflow: visible;
}

.chart {
  grid-row: 1 / 2;
  background-color: var(--color-card-bg);
  border-radius: 0.75rem;
  box-shadow: 0 1px 3px var(--color-card-shadow);
  padding: 1rem;
  padding-bottom: 1rem;
  overflow: visible;
}

.note {
  grid-row: 2 / 3;
  margin: 0.5rem 1.5rem 0;
  font-size: 0.9rem;
  text-align: center;
  border-top: 1px dashed var(--color-note-border);
  padding-top: 0.5rem;
}

/* —— Footer —— */
.footer {
  background-color: #1E40AF;
  padding: 0.75rem 2rem;
  text-align: center;
}

.footer-source {
  color: #F87171;
  font-weight: 500;
  margin-bottom: 0.25rem;
  font-size: 0.95rem;
}

.footer-info {
  color: #E0E7FF;
  font-size: 0.875rem;
}

.footer-info a {
  color: #E0E7FF;
  text-decoration: none;
  transition: color 0.2s;
}

.footer-info a:hover {
  color: #FFF;
  text-decoration: underline;
}

/* ========== 移动端优化 ========== */
@media (max-width: 768px) {
  /* Header */
  .header {
    padding: 0.75rem 1rem;
  }

  .header-brand {
    flex-direction: column;
    align-items: flex-start;
  }

  .platform-title {
    font-size: 1.5rem;
    margin-bottom: 0.25rem;
  }

  .header-logo {
    height: 2rem;
    margin-top: 0.25rem;
  }

  .title-separator {
    margin-bottom: 0.5rem;
  }

  /* 一级菜单 */
  .category-nav {
    display: flex;
    justify-content: flex-start;
    flex-wrap: nowrap;
    overflow-x: auto;
    padding: 0.25rem 0;
    margin-bottom: 0.5rem;
    width: 100%;
    max-width: 100%;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }

  .category-nav::-webkit-scrollbar {
    display: none;
  }

  .category-nav .btn-category {
    flex: 0 0 auto;
    margin: 0 0.25rem;
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
  }

  /* Main 区域调整 */
  .main {
    flex-direction: column;
    padding: 0.5rem 1rem;
  }

  /* 二级菜单 */
  .submenu {
    width: 100%;
    margin-right: 0;
    margin-bottom: 1rem;
    padding: 0.75rem 0.5rem;
    max-height: 25vh;
  }

  .submenu-item {
    padding: 0.4rem 0.5rem;
    margin-bottom: 0.25rem;
    font-size: 0.85rem;
  }

  /* 图表区 */
  .chart-area {
    display: flex;
    flex-direction: column;
    overflow: visible;
  }

  .chart {
    height: 40vh;
    padding: 1rem 0.75rem 3rem;
  }

  .note {
    margin: 0.5rem 0.75rem 0;
    font-size: 0.8rem;
  }

  /* Footer */
  .footer {
    padding: 0.5rem 1rem;
    font-size: 0.8rem;
    line-height: 1.3;
  }

  .footer-source {
    margin-bottom: 0.2rem;
  }
}