/* 通用样式 */
:root {
  --paper: #faf8f2;
  --paper-deep: #efe8dc;
  --ink: #272522;
  --muted: #64615c;
  --link: #1e6074;
  --link-hover: #8c1515;
  --accent: #8c1515;
  --accent-soft: #c9a36f;
  --rule: #d9d1c4;
  --header-start: #1d2530;
  --header-mid: #263d4e;
  --header-end: #3e5a56;
}

body {
  font-family: "Georgia", serif; /* 使用学术风格的字体 */
  line-height: 1.65;
  margin: 0;
  padding: 0;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.58), rgba(255,255,255,0) 260px),
    var(--paper);
  color: var(--ink);
}


@media (max-width: 768px) {
  .nav-links {
    display: none; /* 默认隐藏导航菜单 */
    flex-direction: column; /* 垂直布局 */
    background-color: var(--header-start);
    position: absolute;
    top: 60px;
    right: 0;
    width: 100%;
    text-align: center;
    flex-wrap: wrap;
  }

  .nav-links li {
    margin: 10px 0;
  }

  .menu-toggle {
    display: block; /* 显示菜单按钮 */
  }

  .nav-links.active {
    display: flex; /* 显示导航菜单 */
  }
}

header {
  background:
    radial-gradient(circle at 20% 0%, rgba(201, 163, 111, 0.20), transparent 32%),
    linear-gradient(135deg, var(--header-start) 0%, var(--header-mid) 52%, var(--header-end) 100%);
  color: #ffffff;
  padding: 20px 24px 18px;
  text-align: center;
  border-bottom: 3px solid var(--accent);
  box-shadow: 0 2px 14px rgba(29, 37, 48, 0.18);
}

figcaption {
  text-align: center; /* 文字居中对齐 */
  margin-top: 8px; /* 调整图片与文字的间距 */
  font-size: 0.95rem; /* 设置文字大小 */
  color: var(--muted); /* 设置文字颜色 */
}

.image-row {
  display: flex; /* 启用 Flexbox 布局 */
  justify-content: space-around; /* 图片均匀分布 */
  align-items: center; /* 图片垂直方向对齐 */
  gap: 18px; /* 图片之间的间距 */
  flex-wrap: wrap; /* 自动换行（可选） */
}


/* 图片样式 */
img {
  display: block;
  max-width: 100%;
  height: auto; /* 保持图片比例 */
  margin: 10px 0;
  border: 1px solid var(--rule); /* 图片边框 */
  border-radius: 6px; /* 圆角 */
  object-fit: contain; /* 确保图片完整显示 */
  background: #fff;
}


header h1 {
  margin: 0;
  font-size: 2.05rem;
  letter-spacing: 0.3px; /* 字母间距 */
  font-weight: 600;
}

nav {
  margin-top: 12px;
  display: flex;
  justify-content: center;
  gap: 8px 16px; /* 按钮之间的间距 */
  flex-wrap: wrap;
}

nav a {
  color: #f8f5ed;
  text-decoration: none;
  padding: 6px 12px;
  border: 1px solid rgba(255, 255, 255, 0.24);
  border-radius: 5px;
  font-size: 1rem;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}

nav a:hover {
  background-color: rgba(140, 21, 21, 0.42);
  border-color: rgba(255, 255, 255, 0.52);
  color: #ffffff;
}

/* 主体内容 */
main {
  max-width: 1000px; /* 内容居中显示 */
  margin: 24px auto;
  padding: 22px;
}

section {
  margin-bottom: 20px;
}

section h2 {
  font-size: 1.5rem;
  margin-bottom: 10px;
  border-bottom: 2px solid var(--rule); /* 标题下边框 */
  padding-bottom: 5px;
  color: var(--ink);
}

section h3 {
  margin-top: 28px;
  margin-bottom: 12px;
  color: var(--ink);
  border-bottom: 1px solid var(--rule);
  padding-bottom: 5px;
}

section p {
  margin: 10px 0;
}

.home-hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 285px;
  gap: 32px;
  align-items: start;
  margin-bottom: 18px;
}

.home-kicker {
  color: var(--accent);
  font-size: 0.96rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  margin-top: 0;
}

.home-lead {
  font-size: 1.13rem;
  line-height: 1.58;
  color: var(--ink);
}

.home-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 18px 0 14px;
}

.home-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 34px;
  padding: 4px 14px;
  border-radius: 6px;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: #fff;
  font-size: 0.95rem;
  font-weight: 700;
  text-decoration: none;
}

.home-button:hover {
  background: #6f1111;
  color: #fff;
}

.home-button-secondary {
  background: rgba(255, 255, 255, 0.42);
  color: var(--link);
  border-color: rgba(30, 96, 116, 0.28);
}

.home-button-secondary:hover {
  background: rgba(30, 96, 116, 0.10);
  color: var(--link-hover);
}

.research-pillars {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
}

.research-pillars span {
  border: 1px solid rgba(201, 163, 111, 0.45);
  border-radius: 999px;
  color: var(--muted);
  background: rgba(255, 255, 255, 0.45);
  font-size: 0.88rem;
  padding: 3px 10px;
}

.home-portrait {
  margin: 2px 0 0;
}

.home-portrait img {
  width: 100%;
  max-height: 360px;
  object-fit: cover;
  object-position: center top;
  border-color: rgba(201, 163, 111, 0.60);
  box-shadow: 0 8px 22px rgba(39, 37, 34, 0.10);
}

.home-contact {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin: 18px 0 16px;
  padding: 14px 16px;
  border: 1px solid var(--rule);
  border-left: 4px solid var(--accent-soft);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.42);
}

.home-contact p {
  margin: 0;
}

.home-contact strong {
  color: var(--accent);
}

.home-teaching {
  color: var(--muted);
  font-style: italic;
}

.section-heading-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  border-bottom: 2px solid var(--rule);
  margin: 30px 0 12px;
}

.section-heading-row h2 {
  border-bottom: 0;
  margin: 0;
}

.section-heading-row a {
  font-size: 0.95rem;
}

.home-news {
  font-size: 0.95rem;
}

.news-list {
  list-style: none;
  margin: 0;
  padding: 0 0 0 12px;
  border-left: 2px solid rgba(201, 163, 111, 0.45);
}

.news-list li {
  position: relative;
  line-height: 1.52;
  margin: 0;
  padding: 6px 0 7px 16px;
}

.news-list li::before {
  content: "";
  position: absolute;
  top: 1.08em;
  left: -5px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-soft);
  box-shadow: 0 0 0 3px var(--paper);
}

.paper-list {
  display: grid;
  gap: 13px;
  margin: 18px 0 34px;
}

.paper-item {
  display: grid;
  grid-template-columns: 3.2rem 1fr;
  gap: 13px;
  padding: 14px 16px 13px 14px;
  background: rgba(255, 255, 255, 0.48);
  border: 1px solid var(--rule);
  border-left: 4px solid rgba(201, 163, 111, 0.55);
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(39, 37, 34, 0.045);
}

.paper-featured {
  background:
    linear-gradient(90deg, rgba(140, 21, 21, 0.06), rgba(255, 255, 255, 0.56));
  border-left-color: var(--accent);
}

.paper-number {
  color: var(--accent);
  font-size: 1.05rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  line-height: 1.35;
  text-align: right;
}

.paper-title {
  font-size: 1.04rem;
  font-weight: 600;
  line-height: 1.38;
}

.paper-title a {
  color: var(--ink);
  text-decoration: none;
}

.paper-title a:hover {
  color: var(--link-hover);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.paper-meta {
  color: var(--muted);
  font-size: 0.95rem;
  margin-top: 3px;
}

.paper-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
}

.paper-tag {
  display: inline-flex;
  align-items: center;
  border: 1px solid rgba(30, 96, 116, 0.22);
  border-radius: 999px;
  color: var(--muted);
  background: rgba(250, 248, 242, 0.72);
  font-size: 0.82rem;
  line-height: 1.2;
  padding: 3px 9px;
}

.paper-link {
  color: var(--link);
  text-decoration: none;
}

.paper-link:hover {
  color: var(--link-hover);
  border-color: rgba(140, 21, 21, 0.35);
}

.paper-tag-venue {
  border-color: rgba(140, 21, 21, 0.25);
  color: var(--ink);
}

a {
  color: var(--link);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}

a:hover {
  color: var(--link-hover);
}

small {
  color: var(--muted);
}

li {
  margin-bottom: 5px;
}

@media (max-width: 620px) {
  .home-hero {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .home-portrait {
    max-width: 290px;
    margin-left: auto;
    margin-right: auto;
  }

  .home-contact {
    grid-template-columns: 1fr;
  }

  .section-heading-row {
    align-items: flex-start;
    flex-direction: column;
    gap: 4px;
  }

  .paper-item {
    grid-template-columns: 2.4rem 1fr;
    padding: 12px 13px 12px 10px;
  }

  .paper-number {
    font-size: 0.96rem;
  }
}

::selection {
  background: rgba(201, 163, 111, 0.38);
}







/* 返回顶部按钮 */
#back-to-top {
  position: fixed;
  bottom: 20px;
  right: 20px;
  display: none; /* 默认隐藏 */
  background-color: var(--header-mid); /* 深灰色背景 */
  color: #fff;
  border: none;
  border-radius: 50%;
  padding: 10px 15px;
  font-size: 16px;
  cursor: pointer;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.3); /* 阴影 */
}

#back-to-top:hover {
  background-color: var(--accent); /* 鼠标悬停时的背景 */
}

/* 页脚 */
footer {
  background:
    linear-gradient(135deg, var(--header-start) 0%, var(--header-mid) 55%, var(--header-end) 100%);
  color: #ffffff;
  text-align: center;
  padding: 12px 0;
  margin-top: 34px;
  font-size: 0.9rem;
  border-top: 3px solid var(--accent);
}


/* ===== 新增：数学主页背景样式 ===== */

/* 整个网页：浅米白底色，加很淡的方格 */
body {
  background:
    linear-gradient(
      90deg,
      rgba(40, 65, 85, 0.035) 1px,
      transparent 1px
    ),
    linear-gradient(
      rgba(40, 65, 85, 0.035) 1px,
      transparent 1px
    ),
    #f7f6f2;

  background-size: 32px 32px;
}

/* 顶部姓名与导航区域：深蓝到蓝绿色渐变 */
header {
  background: linear-gradient(
    120deg,
    #182b42 0%,
    #254b62 60%,
    #35635f 100%
  );

  color: #ffffff;
  padding: 30px 20px 24px;
  border-bottom: 3px solid #b99a65;
}

/* 正文：白色底，避免背景纹理干扰阅读 */
main {
  background: #ffffff;
  border: 1px solid #e4e1da;
  border-radius: 12px;
  box-shadow: 0 8px 28px rgba(25, 40, 55, 0.05);
}