* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "SimSun","Times New Roman",serif;
  color: #222;
  background:
    radial-gradient(circle at 10% 10%, #ffffff, transparent 60%),
    radial-gradient(circle at 90% 90%, #e5e5e5, transparent 60%),
    linear-gradient(135deg, #f5f5f5, #dcdcdc);
  min-height: 100vh;
}

/* ================= 导航栏 ================= */
.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(12px);
  z-index: 1000;
}

.navbar ul {
  display: flex;
  justify-content: center;
  list-style: none;
  padding: 1rem;
}

.navbar li {
  margin: 0 1.2rem;
}

.navbar a {
  text-decoration: none;
  color: #555;
  font-weight: 600;
  position: relative;
  padding-bottom: 6px;
}

.navbar a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  height: 2px;
  width: 0;
  background: #000;
  transition: width 0.3s ease;
}

.navbar a:hover::after,
.navbar a.active::after {
  width: 100%;
}

.navbar a.active {
  color: #000;
}

/* ================= 首页 ================= */
.hero {
  height: 100vh;
  background: url("../images/hero.jpg") center/cover no-repeat;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero .hero-inner {
  background: rgba(255,255,255,0.75);
  backdrop-filter: blur(10px);
  padding: 60px;
  border-radius: 24px;
  text-align: center;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.hero p {
  color: #444;
}

/* ================= 模块卡片 ================= */
.module-grid {
  max-width: 1200px;
  margin: 80px auto;
  display: grid;
  grid-template-columns: repeat(auto-fit,minmax(260px,1fr));
  gap: 30px;
  padding: 0 20px;
}

.module-card {
  height: 220px;
  border-radius: 18px;
  background-size: cover;
  background-position: center;
  position: relative;
  text-decoration: none;
  overflow: hidden;
  transition: transform 0.4s ease, box-shadow 0.4s ease;
}

.module-card:hover {
  transform: translateY(-12px);
  box-shadow: 0 25px 45px rgba(0,0,0,0.25);
}

.module-card .overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.45);
  color: #fff;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  padding: 24px;
}

/* ================= 内容页 ================= */
.page {
  max-width: 900px;
  margin: 160px auto 80px;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(10px);
  border-radius: 24px;
  padding: 50px;
}

.page h2 {
  margin-bottom: 20px;
}

.page p {
  line-height: 1.8;
  color: #444;
}

/* ================= 文档展示 ================= */
.file-list {
  margin-top: 30px;
}

.file-list a {
  display: block;
  padding: 12px 0;
  color: #0066cc;
  text-decoration: none;
  border-bottom: 1px solid #ddd;
}

.file-list a:hover {
  color: #000;
}

/* ================= 页面背景容器 ================= */

.page-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background-size: cover;
  background-position: center;
}

.page-bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(
      rgba(255,255,255,0.3),  /* 降低透明度以使背景图像更可见 */
      rgba(255,255,255,0.3)
    );
}

/* ================= 子模块卡片 ================= */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px,1fr));
  gap: 24px;
  margin-top: 30px;
}

.sub-card {
  height: 160px;
  border-radius: 16px;
  background-size: cover;
  background-position: center;
  position: relative;
  overflow: hidden;
  transition: transform .4s, box-shadow .4s;
}

.sub-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 35px rgba(0,0,0,0.25);
}

.sub-card .overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.45);
  color: #fff;
  display: flex;
  align-items: flex-end;
  padding: 16px;
}