/* ==============================================
   基础重置 + SEO全局配置（W3C标准，企业级）
   ============================================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

:root {
  --primary: #165DFF; /* 企业主蓝，官方感强 */
  --primary-dark: #0E4BDB; /* 主色加深，hover用 */
  --secondary: #F5F7FA; /* 浅灰背景，区分板块 */
  --text-main: #333; /* 主文本色，SEO抓取友好 */
  --text-second: #666; /* 次要文本色 */
  --text-light: #999; /* 备注文本色 */
  --white: #FFF;
  --shadow: 0 2px 12px rgba(0,0,0,0.08); /* 轻阴影，企业质感 */
  --container-w: 1200px; /* PC端主容器宽度 */
  --font-base: 16px; /* 基础字体，rem基准 */
}

body {
  font-family: "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", sans-serif;
  font-size: var(--font-base);
  line-height: 1.5;
  color: var(--text-main);
  background: var(--white);
  overflow-x: hidden;
}

/* 语义化标签块级化，利于SEO抓取页面结构 */
header, nav, main, section, footer, article, aside {
  display: block;
}

/* 图片核心样式：响应式+懒加载占位+SEO必加alt */
img {
  max-width: 100%;
  height: auto;
  display: block;
  border: 0;
}

/* 链接样式：SEO友好，伪类完整，交互平滑 */
a {
  color: var(--primary);
  text-decoration: none;
  transition: all 0.3s ease;
}
a:hover {
  color: var(--primary-dark);
  text-decoration: underline;
}
/* 导航/按钮/卡片链接取消下划线，提升体验 */
.nav-link a, .btn a, .card a {
  text-decoration: none;
}

ul, ol {
  list-style: none;
}

button {
  cursor: pointer;
  border: none;
  background: var(--primary);
  color: var(--white);
  transition: all 0.3s ease;
  font-family: inherit;
}
button:hover {
  background: var(--primary-dark);
}

/* 标题层级：SEO核心！单页面仅1个h1，h2-h6按内容层级用，权重分明 */
h1 { font-size: 2.5rem; font-weight: 700; line-height: 1.2; margin-bottom: 1rem; }
h2 { font-size: 2rem; font-weight: 700; line-height: 1.2; margin-bottom: 0.8rem; }
h3 { font-size: 1.5rem; font-weight: 600; line-height: 1.3; margin-bottom: 0.6rem; }
h4 { font-size: 1.25rem; font-weight: 600; line-height: 1.3; margin-bottom: 0.5rem; }
h5 { font-size: 1.1rem; font-weight: 500; line-height: 1.4; margin-bottom: 0.4rem; }
h6 { font-size: 1rem; font-weight: 500; line-height: 1.4; margin-bottom: 0.3rem; }

p { margin-bottom: 1rem; }
p.text-second { color: var(--text-second); font-size: 0.9rem; }

/* 通用容器：居中+响应式，全站统一 */
.container {
  width: 100%;
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 0 20px;
}

/* 清除浮动：布局不塌陷，兼容旧浏览器 */
.clearfix::after {
  content: "";
  display: block;
  clear: both;
  height: 0;
  visibility: hidden;
}

/* SEO友好隐藏：屏幕阅读器可识别，仅视觉隐藏 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  border: 0;
}

/* 懒加载图片占位：避免布局跳动，提升体验 */
.lazy-img {
  background: var(--secondary) url(../images/lazy-loading.png) no-repeat center;
  background-size: 50px;
}

/* 通用按钮样式：企业级，统一视觉 */
.btn {
  display: inline-block;
  padding: 8px 20px;
  background: var(--primary);
  color: var(--white);
  border-radius: 4px;
  font-weight: 600;
}
.btn:hover {
  background: var(--primary-dark);
  color: var(--white);
}
.btn-big {
  padding: 15px 40px;
  font-size: 1.2rem;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(22,93,255,0.3);
}
.btn-big:hover {
  box-shadow: 0 6px 16px rgba(22,93,255,0.4);
  transform: translateY(-2px);
}

/* 回到顶部按钮：固定定位+滚动显示，z-index防遮挡 */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 48px;
  height: 48px;
  background: var(--primary) url(../images/icon-top.png) no-repeat center;
  background-size: 32px;
  border-radius: 50%;
  box-shadow: var(--shadow);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 999;
}
.back-to-top.show {
  opacity: 1;
  visibility: visible;
}

/* ==============================================
   头部导航：LOGO双尺寸+吸顶+响应式，核心不隐藏
   ============================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: var(--white);
  z-index: 9999;
  transition: all 0.3s ease;
  padding: 15px 0;
}
/* 滚动吸顶添加阴影，提升视觉 */
.header.sticky {
  box-shadow: var(--shadow);
  padding: 10px 0;
}
.header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
/* LOGO：显式img标签，比CSS背景更SEO友好，双尺寸适配 */
.logo img {
  height: 60px;
  width: auto;
}
.logo-sm {
  display: none;
  height: 45px;
  width: auto;
}
/* 桌面端导航 */
.nav {
  display: flex;
  align-items: center;
  gap: 20px;
}
.nav-list {
  display: flex;
  gap: 30px;
}
.nav-link {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-main);
  position: relative;
  padding: 8px 0;
}
.nav-link.active, .nav-link:hover {
  color: var(--primary);
}
/* 导航激活/hover下划线，企业级样式 */
.nav-link.active::after, .nav-link:hover::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--primary);
  border-radius: 1px;
}
.download-nav-btn {
  white-space: nowrap;
}

/* ==============================================
   主内容区：避开固定导航，统一上边距
   ============================================== */
.main {
  margin-top: 90px;
  padding-bottom: 60px;
}

/* ==============================================
   轮播Banner：核心下载区+3图轮播，SEO强化关键词
   ============================================== */
.banner {
  width: 100%;
  height: calc(100vh - 90px);
  min-height: 600px;
  position: relative;
  overflow: hidden;
}
/* 轮播容器 */
.banner-carousel {
  width: 100%;
  height: 100%;
  position: relative;
}
/* 轮播项：绝对定位，默认隐藏 */
.banner-item {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  transition: opacity 0.8s ease-in-out;
  z-index: 1;
}
/* 激活项显示 */
.banner-item.active {
  opacity: 1;
  z-index: 2;
}
/* 轮播图片：覆盖整个容器，保证视觉 */
.banner-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
/* 轮播遮罩：提升文字可读性，不遮挡图片 */
.banner-mask {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.3);
  z-index: 3;
}
/* 轮播文字内容：居中+白色，SEO核心关键词区 */
.banner-content {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: var(--white);
  text-align: center;
  z-index: 4;
  max-width: 800px;
  width: 100%;
  padding: 0 20px;
}
.banner-content h1 {
  font-size: 3rem;
  margin-bottom: 2rem;
}
/* 核心关键词高亮，强化SEO */
.banner-content h1 span {
  color: var(--primary);
  font-weight: 800;
}
.banner-content p {
  font-size: 1.2rem;
  margin-bottom: 2.5rem;
  color: var(--white);
  line-height: 1.6;
}
/* 轮播指示器：小圆点，手动切换 */
.banner-indicator {
  position: absolute;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 12px;
  z-index: 4;
}
.indicator-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: rgba(255,255,255,0.5);
  cursor: pointer;
  transition: all 0.3s ease;
}
.indicator-dot.active {
  background: var(--primary);
  width: 30px;
  border-radius: 6px;
}

/* ==============================================
   板块通用样式：统一标题+间距，SEO内容块清晰
   ============================================== */
.section {
  padding: 80px 0;
}
.section-title {
  text-align: center;
  margin-bottom: 60px;
}
.section-title h2 {
  position: relative;
  display: inline-block;
  padding-bottom: 15px;
}
/* 板块标题下划线，企业级装饰，统一视觉 */
.section-title h2::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: var(--primary);
  border-radius: 1.5px;
}
.section-title p {
  max-width: 800px;
  margin: 0 auto;
  color: var(--text-second);
}

/* ==============================================
   核心功能展示：4图卡片，图文结合提升SEO收录
   ============================================== */
.function {
  background: var(--secondary);
}
.function-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 30px;
}
.function-card {
  background: var(--white);
  box-shadow: var(--shadow);
  border-radius: 8px;
  padding: 30px 20px;
  text-align: center;
  transition: all 0.3s ease;
}
.function-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.12);
}
.function-img {
  width: 120px;
  height: 120px;
  margin: 0 auto 20px;
  border-radius: 50%;
  background: var(--secondary);
  display: flex;
  align-items: center;
  justify-content: center;
}
.function-img img {
  width: 80px;
  height: 80px;
  object-fit: contain;
}
.function-card h3 {
  margin-bottom: 15px;
}
.function-card p {
  color: var(--text-second);
  font-size: 0.9rem;
  line-height: 1.6;
}

/* ==============================================
   版本优势展示：3图横向，突出正版/最新/极速
   ============================================== */
.advantage-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 40px;
  align-items: center;
}
.advantage-card {
  display: flex;
  flex-direction: column;
  gap: 20px;
  text-align: center;
}
.advantage-img {
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow);
  height: 200px;
}
.advantage-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: all 0.5s ease;
}
.advantage-card:hover .advantage-img img {
  transform: scale(1.05);
}
.advantage-card h3 {
  color: var(--primary);
}
.advantage-card p {
  color: var(--text-second);
}

/* ==============================================
   新闻展示：3图卡片，主页图文引流，提升收录
   ============================================== */
.news-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 30px;
}
.news-card {
  background: var(--white);
  box-shadow: var(--shadow);
  border-radius: 8px;
  overflow: hidden;
  transition: all 0.3s ease;
}
.news-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.12);
}
.news-img {
  height: 200px;
  overflow: hidden;
}
.news-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: all 0.5s ease;
}
.news-card:hover .news-img img {
  transform: scale(1.05);
}
.news-content {
  padding: 20px;
}
.news-title {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-bottom: 10px;
}
.news-desc {
  font-size: 0.9rem;
  color: var(--text-second);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin-bottom: 15px;
}
.news-time {
  font-size: 0.8rem;
  color: var(--text-light);
}
/* 新闻查看更多按钮，居中 */
.news-more {
  text-align: center;
  margin-top: 40px;
}

/* ==============================================
   页脚：企业级+LOGO+底部导航+备案，SEO必备
   ============================================== */
.footer {
  width: 100%;
  background: url(../images/bg-footer.png) no-repeat center;
  background-size: cover;
  color: var(--white);
  padding: 60px 0 20px;
  position: relative;
}
/* 页脚遮罩，提升文字可读性 */
.footer-mask {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.7);
  z-index: 1;
}
.footer .container {
  position: relative;
  z-index: 2;
}
.footer-top {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 40px;
  margin-bottom: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255,255,255,0.2);
}
.footer-logo img {
  height: 60px;
  width: auto;
  margin-bottom: 20px;
}
.footer-desc {
  max-width: 300px;
  font-size: 0.9rem;
  line-height: 1.6;
  color: rgba(255,255,255,0.8);
}
.footer-nav h4 {
  font-size: 1.2rem;
  margin-bottom: 20px;
  border-left: 4px solid var(--primary);
  padding-left: 10px;
  color: var(--white);
}
.footer-nav-list li {
  margin-bottom: 10px;
}
.footer-nav-list a {
  color: rgba(255,255,255,0.8);
}
.footer-nav-list a:hover {
  color: var(--primary);
  text-decoration: none;
}
/* 版权+备案：SEO核心，提升网站权威性 */
.footer-bottom {
  text-align: center;
  font-size: 0.8rem;
  color: rgba(255,255,255,0.6);
  padding-top: 20px;
}
.footer-bottom a {
  color: rgba(255,255,255,0.6);
}
.footer-bottom a:hover {
  color: var(--primary);
}

/* ==============================================
   响应式适配：平板+移动端，核心内容不隐藏，SEO不丢失
   ============================================== */
/* 平板（768px - 992px） */
@media (max-width: 992px) {
  :root { --font-base: 15px; }
  h1 { font-size: 2.2rem; }
  h2 { font-size: 1.8rem; }
  .banner-content h1 { font-size: 2.5rem; }
  .nav-list { gap: 20px; }
  .function-list { grid-template-columns: repeat(2, 1fr); }
  .advantage-list { gap: 30px; }
}

/* 移动端（≤767px）：核心适配，保留所有功能 */
@media (max-width: 767px) {
  :root { --font-base: 14px; }
  h1 { font-size: 1.8rem; }
  h2 { font-size: 1.5rem; }

  /* 头部导航 */
  .header { padding: 10px 0; }
  .logo { display: none; }
  .logo-sm { display: block; }
  .nav-list { gap: 10px; }
  .nav-link { font-size: 0.9rem; }
  .download-nav-btn { padding: 6px 12px; font-size: 0.9rem; }

  /* 轮播Banner */
  .banner { height: calc(100vh - 70px); min-height: 400px; }
  .banner-content h1 { font-size: 1.8rem; margin-bottom: 1.5rem; }
  .banner-content p { font-size: 1rem; margin-bottom: 2rem; }
  .btn-big { padding: 12px 30px; font-size: 1rem; }
  .indicator-dot { width: 10px; height: 10px; }
  .indicator-dot.active { width: 25px; }

  /* 板块间距 */
  .section { padding: 40px 0; }
  .section-title { margin-bottom: 30px; }

  /* 功能/优势/新闻：单列展示 */
  .function-list { grid-template-columns: 1fr; gap: 20px; }
  .advantage-list { grid-template-columns: 1fr; gap: 20px; }
  .news-list { grid-template-columns: 1fr; gap: 20px; }

  /* 页脚：单列展示 */
  .footer-top { flex-direction: column; gap: 30px; }
  .footer-nav { width: 100%; }
  .footer-logo img { height: 45px; }

  /* 回到顶部：位置调整 */
  .back-to-top { bottom: 20px; right: 20px; width: 40px; height: 40px; background-size: 24px; }
}