* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
:root {
  --primary-dark: #1f443c;
  --primary-light: #7cc8b8;
  --bg-base: #f8faf9;
  --text-main: #22332e;
  --card-bg: rgba(255,255,255,0.72);
  --border-subtle: rgba(124,200,184,0.25);
}
html {
  scroll-behavior: smooth;
}
body {
  background-color: var(--bg-base);
  color: var(--text-main);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.7;
  overflow-x: hidden;
}

/* 导航栏 */
nav {
  position: fixed;
  width: 100%;
  top:0;
  z-index: 100;
  padding: 1.3rem 4rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: background 0.4s ease, box-shadow 0.4s ease;
}
nav.scrolled {
  background-color: var(--primary-dark);
  box-shadow: 0 2px 12px rgba(31,68,60,0.12);
}
.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: 0.5px;
}
.nav-group a {
  color: rgba(255,255,255,0.85);
  text-decoration: none;
  margin-left: 2rem;
  transition: color 0.3s ease;
}
.nav-group a:hover {
  color: var(--primary-light);
}

/* Hero区块 粒子+科技背景 */
.hero-block {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 0 2rem;
  background: linear-gradient(135deg, #28574b, #1f443c);
  overflow: hidden;
}
#particleCanvas {
  position: absolute;
  inset:0;
  opacity:0.22;
}
.hero-content {
  position: relative;
  z-index:2;
  text-align:center;
  max-width:800px;
}
.hero-block h1 {
  font-size: 3.4rem;
  color:#fff;
  margin-bottom:1.4rem;
  letter-spacing: 1px;
}
.hero-block p {
  color:rgba(255,255,255,0.88);
  font-size:1.22rem;
  margin-bottom: 2.4rem;
}
.btn-primary {
  display:inline-block;
  padding:1.1rem 2.4rem;
  background: var(--primary-light);
  color: var(--primary-dark);
  font-weight:700;
  border-radius:999px;
  text-decoration:none;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 20px rgba(124,200,184,0.35);
}
/* 底部扫光线条 */
.light-sweep {
  position:absolute;
  bottom: 80px;
  width:320px;
  height:1px;
  background: linear-gradient(90deg, transparent, #7cc8b8, transparent);
  animation: sweep 4.5s infinite linear;
}
@keyframes sweep {
  0% {transform: translateX(-180px); opacity:0.3;}
  50% {opacity:0.9;}
  100% {transform: translateX(180px); opacity:0.3;}
}

/* 通用容器，滚动渐显 */
.container {
  max-width:1260px;
  margin:0 auto;
  padding:6rem 2rem;
}
.section-heading {
  font-size:2.2rem;
  color:var(--primary-dark);
  margin-bottom:1.2rem;
  position:relative;
}
.section-heading::after {
  content:"";
  display:block;
  width:70px;
  height:3px;
  background:var(--primary-light);
  margin-top:0.6rem;
}
.fade-in {
  opacity:0;
  transform: translateY(26px);
  transition: opacity 0.7s ease-out, transform 0.7s ease-out;
}
.fade-in.active {
  opacity:1;
  transform: translateY(0);
}

/* 科技卡片网格 */
.card-grid {
  display:grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap:2.2rem;
  margin-top:3rem;
}
.card-item {
  background: var(--card-bg);
  border:1px solid var(--border-subtle);
  border-radius:16px;
  padding:2.4rem;
  backdrop-filter: blur(8px);
  transition: transform 0.35s ease, box-shadow 0.35s ease, border-color 0.35s ease;
}
.card-item:hover {
  transform: translateY(-6px);
  box-shadow: 0 12px 30px rgba(31,68,60,0.1);
  border-color:rgba(124,200,184,0.55);
}
.card-item h3 {
  color:var(--primary-dark);
  font-size:1.35rem;
  margin-bottom: 0.8rem;
}

/* 页脚 */
footer {
  background-color: var(--primary-dark);
  color:rgba(255,255,255,0.8);
  text-align:center;
  padding:2.6rem;
  margin-top:3rem;
}
/* 响应式适配 */
@media(max-width:900px){
  nav {padding:1rem 1.5rem;}
  .nav-group a {margin-left:1rem;}
  .hero-block h1 {font-size: 2.2rem;}
}