/* ===== 全局与主题 ===== */
:root{
  --container: 1200px;
  --dark-text: #111;         /* 深色文本（第1页，浅色背景） */
  --light-text: #e9edf3;     /* 浅色文本（2-5页，深色背景） */
  --accent: #6ee7ff;         /* 霓虹蓝绿色点缀 */
  --muted: rgba(255,255,255,.65);
  --card-bg: rgba(255,255,255,.06);
  --card-bd: rgba(255,255,255,.12);
}

*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  font-family: "Inter", system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  line-height: 1.6;
  background: #0b0f14;
  color: var(--light-text);
}

/* ===== 布局 ===== */
.container{
  width: min(92%, var(--container));
  margin: 0 auto;
}

.section{
  padding: 96px 0;
  position: relative;
  background-size: cover;
  background-position: center;
}

.light-bg{ /* 第1页：放浅色背景图片（用户后续自行替换） */
  background: url('./bg_image.png');
  color: var(--dark-text);
}

.dark-bg{  /* 第2-5页：放深色背景图片（用户后续自行替换） */
  background:url('./image.png');
  color: var(--light-text);
}

/* ===== 头部导航 ===== */
.site-header{
  position: sticky; top:0; z-index: 1000;
  backdrop-filter: blur(10px);
  background: linear-gradient( to bottom, rgba(15,18,24,.85), rgba(15,18,24,.55) );
  border-bottom: 1px solid rgba(255,255,255,.08);
}
.header-inner{
  display:flex; align-items:center; justify-content:space-between;
  height: 68px;
}
.brand{font-weight:700; letter-spacing:.5px; color:#fff}
.nav a{
  color:#cfe6ff; text-decoration:none; margin-left: 20px; font-weight:600;
  padding: 10px 4px; border-bottom:2px solid transparent;
}
.nav a:hover{ border-color: var(--accent); color:#fff; }

/* ===== 第1屏布局 ===== */
.first-screen{min-height: 100vh; display: grid; align-items: start; padding-top: 40px; }
.intro-grid{
  display:grid; grid-template-columns: 1fr 1.2fr; gap: 32px;
}
.title{font-size: clamp(28px, 4vw, 44px); margin:0 0 8px}
.accent{color:#0066cc}
.subtitle{margin:0 0 12px; opacity:.8; font-weight:600}
.intro-text{margin-bottom: 12px; opacity:.9}
.bullets{padding-left: 18px; margin: 0}
.bullets li{margin: 6px 0}

.radar{ width: 100%; height: 360px; border-radius: 16px; }

/* ===== 通用标题 ===== */
.section-title{
  font-size: clamp(22px, 3vw, 32px);
  margin: 0 0 24px;
  letter-spacing:.5px;
}

/* ===== 卡片布局 ===== */
.cards{
  display:grid; gap: 20px;
}
.cards.two{ grid-template-columns: repeat(2, minmax(0,1fr)); }
.cards.three{ grid-template-columns: repeat(3, minmax(0,1fr)); }

.card{
  border: 1px solid var(--card-bd);
  background: var(--card-bg);
  border-radius: 14px;
  padding: 18px 18px 16px;
  box-shadow: 0 10px 30px rgba(0,0,0,.18);
}
.card h3{ margin: 6px 0 8px; font-size: 18px; }
.card p{ margin: 0 0 10px; color: var(--muted); }
.meta{padding-left:18px; margin: 0; color: var(--muted); font-size: 14px;}
.meta li{margin:4px 0}

/* ===== 时间轴（技术背景） ===== */
.timeline{position:relative; margin: 8px 0 0; padding-left: 18px;}
.timeline::before{
  content:""; position:absolute; left:6px; top:0; bottom:0; width:2px; background: rgba(255,255,255,.18);
}
.t-item{position:relative; padding-left: 18px; margin: 16px 0;}
.t-dot{position:absolute; left:-2px; top:6px; width:10px; height:10px; border-radius:50%; background: var(--accent); box-shadow:0 0 0 3px rgba(110,231,255,.2);}
.t-content h3{margin:0 0 6px}
.t-content p{margin:0; color: var(--muted)}

/* ===== 按钮 ===== */
.btn-outline{
  display:inline-block; padding:8px 12px; border:1px solid rgba(255,255,255,.35);
  border-radius:10px; color:#e8f3ff; text-decoration:none; font-size:14px;
}
.btn-outline:hover{ border-color:#fff; color:#fff; }

/* ===== 联系方式 ===== */
.contact-wrap{ display:grid; gap:14px; }
.contact-card{
  width: min(520px, 100%);
  border:1px solid var(--card-bd);
  background: var(--card-bg);
  border-radius: 14px;
  padding: 12px 14px;
}
.contact-card .row{ display:flex; gap:12px; align-items:center; padding:6px 4px; }
.contact-card .label{ width:52px; opacity:.7; font-size: 14px;}
.contact-card .value{ color:#e8f3ff; text-decoration:none; font-weight:600; font-size:14px; }

/* ===== 页脚 ===== */
.site-footer{ border-top:1px solid rgba(255,255,255,.08); padding: 28px 0; text-align:center; color: rgba(255,255,255,.6); background: #0b0f14; }

/* ===== 响应式 ===== */
@media (max-width: 960px){
  .intro-grid{ grid-template-columns: 1fr; }
  .cards.two{ grid-template-columns: 1fr; }
  .cards.three{ grid-template-columns: 1fr; }
  .radar{ height: 300px; }
}