/* ======================================
   全局重置与基础样式
   ====================================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Segoe UI", "Roboto", "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.7;
  color: #333;
  background-color: #f8fafc; /* 极浅灰蓝背景，SaaS 标配 */
  overflow-x: hidden;
}

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

.container {
  width: 92%;
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
  z-index: 2;
}

/* ======================================
   按钮通用样式（SaaS 专业按钮）
   ====================================== */
.btn {
  display: inline-block;
  padding: 14px 32px;
  background-color: #2563eb; /* 主色调：科技蓝 */
  color: #fff;
  border-radius: 8px; /* 微圆角，专业感 */
  font-weight: 600;
  font-size: 15px;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
}

.btn:hover {
  background-color: #1d4ed8;
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(37, 99, 235, 0.15);
}

.btn-sm {
  padding: 8px 18px;
  font-size: 13px;
  background-color: #2563eb;
  color: #fff;
  border-radius: 6px;
  transition: all 0.3s;
}

.btn-sm:hover {
  background-color: #1d4ed8;
}

/* ======================================
   导航栏（极简科技风）
   ====================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 999;
  padding: 20px 0;
  transition: all 0.3s ease;
  background-color: rgba(255, 255, 255, 0.95);
  border-bottom: 1px solid #e2e8f0;
}

.header.sticky {
  padding: 12px 0;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 24px;
  font-weight: 700;
  color: #1e293b; /* 深灰文字，高级 */
}

.logo span {
  font-size: 14px;
  font-weight: 400;
  color: #64748b;
  margin-left: 8px;
}

.nav ul {
  display: flex;
  gap: 30px;
}

.nav ul li a {
  color: #475569;
  font-size: 15px;
  font-weight: 500;
  transition: color 0.3s;
}

.nav ul li a:hover {
  color: #2563eb;
}

.menu-toggle {
  display: none;
  font-size: 24px;
  color: #1e293b;
  cursor: pointer;
}

/* ======================================
   首屏 Hero（大气、简洁、专业）
   ====================================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: #1e293b;
  padding: 100px 0 60px;
  background-color: #fff;
  position: relative;
}

.hero h1 {
  font-size: 48px;
  line-height: 1.2;
  margin-bottom: 24px;
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
  font-weight: 700;
}

.hero p {
  font-size: 19px;
  max-width: 700px;
  margin: 0 auto 40px;
  color: #64748b;
}

/* ======================================
   关于我们（专业、沉稳）
   ====================================== */
.about {
  padding: 100px 0;
  background-color: #fff;
}

.about h2 {
  text-align: center;
  font-size: 36px;
  margin-bottom: 60px;
  color: #1e293b;
  font-weight: 700;
}

.about-content {
  display: flex;
  align-items: center;
  gap: 60px;
}

.about-text {
  flex: 1;
}

.about-text h3 {
  font-size: 26px;
  margin-bottom: 24px;
  color: #2563eb;
  font-weight: 600;
}

.about-text p {
  line-height: 1.9;
  margin-bottom: 24px;
  color: #475569;
  font-size: 16px;
}

.about-features li {
  margin: 12px 0;
  color: #475569;
  display: flex;
  align-items: center;
  font-size: 16px;
}

.about-features i {
  color: #10b981; /* 点缀色：成功绿 */
  margin-right: 12px;
  font-size: 18px;
}

.about-img {
  flex: 1;
  text-align: center;
  color: #2563eb;
}

/* ======================================
   服务板块（卡片式设计，SaaS 核心）
   ====================================== */
.services {
  padding: 100px 0;
  background-color: #f8fafc;
}

.services h2 {
  text-align: center;
  font-size: 36px;
  margin-bottom: 60px;
  color: #1e293b;
  font-weight: 700;
}

.services-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 35px;
}

.service-card {
  background-color: #fff;
  padding: 45px 30px;
  border-radius: 16px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.04);
  border: 1px solid #e2e8f0;
  transition: all 0.3s ease;
  text-align: center;
}

.service-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 15px 30px rgba(37, 99, 235, 0.08);
  border-color: #cbd5e1;
}

.service-card i {
  font-size: 48px;
  color: #2563eb;
  margin-bottom: 24px;
}

.service-card h3 {
  font-size: 22px;
  margin-bottom: 16px;
  color: #1e293b;
  font-weight: 600;
}

.service-card p {
  font-size: 16px;
  color: #64748b;
  line-height: 1.8;
}

/* ======================================
   案例展示（简洁卡片）
   ====================================== */
.portfolio {
  padding: 100px 0;
  background-color: #fff;
}

.portfolio h2 {
  text-align: center;
  font-size: 36px;
  margin-bottom: 60px;
  color: #1e293b;
  font-weight: 700;
}

.portfolio-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 35px;
}

.portfolio-card {
  background-color: #fff;
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid #e2e8f0;
  transition: all 0.3s;
}

.portfolio-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 15px 30px rgba(37, 99, 235, 0.08);
  border-color: #cbd5e1;
}

.portfolio-img {
  height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: #eff6ff;
  color: #2563eb;
}

.portfolio-info {
  padding: 30px;
}

.portfolio-info h3 {
  font-size: 20px;
  margin-bottom: 12px;
  color: #1e293b;
  font-weight: 600;
}

.portfolio-info p {
  font-size: 15px;
  color: #64748b;
  margin-bottom: 20px;
  line-height: 1.7;
}

/* ======================================
   页脚（极简、专业）
   ====================================== */
.footer {
  background-color: #1e293b;
  color: rgba(255, 255, 255, 0.7);
  padding: 50px 0;
  text-align: center;
  font-size: 14px;
}

.footer p {
  margin-bottom: 10px;
}

/* ======================================
   返回顶部按钮
   ====================================== */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  background-color: #2563eb;
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 99;
}

.back-to-top.show {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  background-color: #1d4ed8;
  transform: translateY(-3px);
}

/* ======================================
   响应式（移动端适配）
   ====================================== */
@media (max-width: 992px) {
  .services-grid,
  .portfolio-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .about-content {
    flex-direction: column;
    text-align: center;
    gap: 40px;
  }
}

@media (max-width: 768px) {
  .nav {
    position: fixed;
    top: 70px;
    left: 0;
    width: 100%;
    background-color: #fff;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    padding: 30px 0;
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s ease;
  }
  .nav.active {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }
  .nav ul {
    flex-direction: column;
    align-items: center;
    gap: 24px;
  }
  .menu-toggle {
    display: block;
  }
  .hero h1 {
    font-size: 38px;
  }
  .hero p {
    font-size: 18px;
  }
  .services-grid,
  .portfolio-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 32px;
  }
  .about h2,
  .services h2,
  .portfolio h2 {
    font-size: 28px;
  }
}