/* 全局重置 (保持一致) */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  background-color: #0a0a0a;
  color: #ffffff;
  font-family: "Microsoft YaHei", "PingFang SC", -apple-system, sans-serif;
  /* 默认等线/无衬线 */
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* 导航栏样式 (完全复用) */
.navbar {
  height: 60px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 24px;
  background-color: #0a0a0a;
  position: relative;
  border-bottom: 1px solid #1a1a1a;
  z-index: 10;
}

.nav-left,
.nav-right {
  width: auto;
}

.nav-left .back-btn {
  background: none;
  border: none;
  color: #ccc;
  font-size: 14px;
  font-family: "Microsoft YaHei", sans-serif;
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
}

.nav-left .back-btn:hover {
  color: #fff;
}

.nav-center {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
}

.brand-title {
  font-size: 16px;
  font-weight: 500;
  color: #fff;
  font-family: "SimSun", serif;
}

.brand-subtitle {
  font-size: 10px;
  color: #fff;
  letter-spacing: 2px;
  margin-top: 2px;
}

.nav-right {
  display: flex;
  gap: 16px;
}

.nav-link {
  font-size: 15px;
  color: #999;
  text-decoration: none;
  padding: 6px 12px;
  border-radius: 4px;
  transition: all 0.2s;
}

.nav-link:hover,
.nav-link.active {
  background-color: #00b386;
  color: #fff;
}

/* --- 科学原理页独有样式 --- */

.main-container {
  max-width: 1200px;
  /* 控制整体宽度，使其聚焦 */
  margin: 0 auto;
  padding: 40px 24px;
  width: 100%;
}

/* 头部 */
.science-header {
  text-align: center;
  margin-bottom: 20px;
}

.page-title {
  font-family: "SimSun", "Songti SC", serif;
  /* 宋体 */
  font-size: 42px;
  font-weight: 800;

  background: linear-gradient(90deg, #00b386, #f9d500);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  margin-bottom: 12px;
}

.page-subtitle {
  font-size: 16px;
  color: #fff;
  /* 白色 */
  font-weight: normal;
  letter-spacing: 1px;
}

/* 分割线 */
.divider-line {
  width: 100%;
  height: 1px;
  background-color: #333;
  /* 灰色长线 */
  margin-bottom: 40px;
}

/* 灰色圆角卡片模块 */
.science-card {
  background-color: #141414;
  /* 深灰色背景 */
  border-radius: 16px;
  /* 四周圆弧 */
  padding: 48px;

  border: 1px solid #222;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
  opacity: 0;
  /* 初始隐藏，用于JS动画 */
  transform: translateY(20px);
  margin-top: 50px;
}

.card-main-title {
  text-align: center;
  font-family: "SimSun", serif;
  /* 宋体 */
  font-size: 26px;
  /* 标题稍大 */
  font-weight: 900;
  /* 字重中等 */
  color: #fff;
  margin-bottom: 40px;
  letter-spacing: 2px;
}

/* 左右两栏布局 */
.card-content {
  display: flex;
  gap: 60px;
  /* 左右间距 */
  align-items: flex-start;
}

.left-column {
  flex: 1.2;
}

.right-column {
  flex: 1;
}

/* 左侧文字 */
.text-block p {
  font-size: 19px;
  line-height: 1.8;
  color: #ccc;
  margin-bottom: 20px;
  text-align: justify;
  /* 两端对齐 */
}

/* 公式模块 */
.formula-box {
  margin-top: 32px;
  background-color: rgba(0, 179, 134, 0.05);
  /* 绿色有点透明的背景 */
  border: 1px solid #004d39;
  /* 深绿色边框 */
  border-radius: 8px;
  padding: 20px 24px;
}

.formula-label {
  font-size: 19px;
  color: #a2a2a2;
  /* 灰色 */
  margin-bottom: 8px;
  font-weight: 500;
}

.formula-main {
  font-family: "Consolas", "Monaco", "Courier New", monospace;
  /* 等宽/公式字体 */
  font-size: 28px;
  color: #00b386;
  /* 绿色 */
  margin-bottom: 12px;
  letter-spacing: 1px;
}

.formula-legend {
  font-size: 18px;
  color: #c6c5c5;
  /* 灰色 */
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.separator {
  color: #333;
}

/* 右侧时间轴 */
.timeline-header {
  font-size: 22px;
  color: #e3c478;
  font-weight: 500;
  margin-bottom: 24px;
}

.timeline-container {
  position: relative;
  padding-left: 20px;
  /* 为线条留出空间 */
}

.timeline-line-img {
  position: absolute;
  left: -67px;
  top: -36px;
  bottom: 0;
  width: 130px;
  height: 150%;
  object-fit: fill;
  z-index: 1;
}


.timeline-item {
  position: relative;
  margin-bottom: 40px;
  /* 增加一点间距 */
}

.timeline-item:last-child {
  margin-bottom: 0;
}



.stage-title {
  font-size: 22px;
  font-weight: 500;
  /* 字重中等 */
  color: #e3c478;
  margin-bottom: 4px;
  font-family: "SimSun", "宋体", serif;
}

.stage-desc {
  font-size: 19px;
  color: #888;
  /* 灰色 */
  line-height: 1.5;
}

/* 响应式调整 */
@media (max-width: 768px) {
  .card-content {
    flex-direction: column;
    gap: 40px;
  }

  .science-card {
    padding: 24px;
  }
}



@media screen and (max-width: 1024px) {

  body {
    height: auto;
    overflow-y: auto;
    min-height: 100vh;
  }

  .navbar {
    height: auto;
    padding: 12px 16px;
    flex-wrap: wrap;
    /* 允许换行 */
  }

  .nav-left {
    flex: 1;
    /* 返回按钮靠左 */
  }

  .nav-center {
    position: static;
    transform: none;
    flex: 1;
    text-align: center;
  }

  .nav-right {
    width: 100%;
    margin-top: 16px;
    display: flex;
    justify-content: flex-start;
    gap: 12px;
    overflow-x: auto;
    /* 超出屏幕可横向滑动 */
    padding-bottom: 8px;
    /* 给滑动条留一点空间 */
    -webkit-overflow-scrolling: touch;
    /* 丝滑滚动 */
  }

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

  .nav-link {
    white-space: nowrap;
    /* 文字不换行 */
  }

  /* 3. 页面主容器 */
  .main-container {
    padding: 16px;
    height: auto;
    overflow: visible;
  }

  .content-wrapper {
    flex-direction: column;
    /* 变为上下结构 */
    height: auto;
    overflow: visible;
    gap: 24px;
  }

}