/* ============================================================
   雪龙云企官方首页 · 纯 HTML/CSS/JS（方案A）
   动态渐变背景：CSS 定义基础渐变与变量，js/main.js 驱动动画
   ============================================================ */
:root {
  --c-primary: #b3272e;
  --c-primary-dark: #8e1f24;
  --c-text: #1d2129;
  --c-text-2: #4e5969;
  --c-text-3: #6b7280;
  --c-line: rgba(255, 255, 255, 0.22);
  --radius: 12px;
  --shadow: 0 12px 34px rgba(0, 0, 0, 0.18);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  /* 渐变动画参数（JS 实时更新 --gx/--gy） */
  --g1: 129, 45, 48;      /* 深红  */
  --g2: 45, 74, 108;      /* 深蓝  */
  --g3: 18, 24, 46;       /* 藏青  */
  --gx: 50%;  /* 主光点 x */
  --gy: 35%;  /* 主光点 y */
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font);
  color: #eef0f6;
  line-height: 1.7;
  /* 兜底纯色（旧浏览器无渐变时） */
  background-color: #12182e;
  /* 基础三色渐变：即使 JS 被禁用也有静态渐变 */
  background-image:
    radial-gradient(1100px 900px at var(--gx) var(--gy), rgb(var(--g1)), transparent 60%),
    radial-gradient(900px 700px at calc(100% - var(--gx)) calc(100% - var(--gy)), rgb(var(--g2)), transparent 60%),
    linear-gradient(135deg, #12182e 0%, #1b2740 45%, #2a1640 100%);
  background-attachment: fixed;
  min-height: 100vh;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }

.container { width: min(1180px, 100% - 40px); margin: 0 auto; }

/* ---------- 居中偏上 Emoji ---------- */
.emoji-center {
  position: fixed;
  top: 30%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 120px;
  line-height: 1;
  z-index: 10;
}

/* ---------- 动态渐变光斑层（js/main.js 负责平滑移动 + 渐入） ---------- */
.bg-glow {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  opacity: 0;
  transition: opacity 1.2s ease;
  will-change: transform;
}
.bg-glow.is-on { opacity: 1; }

/* ---------- 顶部导航 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 14, 30, 0.55);
  -webkit-backdrop-filter: saturate(160%) blur(14px);
  backdrop-filter: saturate(160%) blur(14px);
  border-bottom: 1px solid var(--c-line);
}
.nav { height: 68px; display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 20px; color: #fff; }
.brand .logo {
  width: 34px; height: 34px; border-radius: 8px;
  background: linear-gradient(135deg, var(--c-primary), var(--c-primary-dark));
  display: grid; place-items: center; font-weight: 800; font-size: 18px;
}
.nav-menu { display: flex; gap: 6px; list-style: none; }
.nav-menu a {
  display: block; padding: 8px 16px; border-radius: 8px;
  color: rgba(255,255,255,.82); font-size: 15px; transition: all .2s;
}
.nav-menu a:hover { color: #fff; background: rgba(255,255,255,.12); }
.nav-menu a.active { color: #fff; font-weight: 600; background: rgba(255,255,255,.16); }
.nav-toggle { display: none; flex-direction: column; gap: 5px; background: none; border: 0; cursor: pointer; padding: 6px; }
.nav-toggle span { width: 22px; height: 2px; background: #fff; border-radius: 2px; }

/* ---------- Hero 首屏 ---------- */
.hero { padding: 110px 0 130px; text-align: center; }
.hero-inner { position: relative; }
.hero h1 {
  font-size: clamp(30px, 5vw, 54px);
  line-height: 1.22; font-weight: 800; color: #fff;
  text-shadow: 0 4px 30px rgba(0,0,0,.35);
}
.hero h1 em { font-style: normal; color: #ffd4a0; }
.hero-sub { max-width: 640px; margin: 22px auto 0; color: rgba(255,255,255,.82); font-size: 17px; }
.hero-actions { margin-top: 38px; display: flex; justify-content: center; gap: 16px; flex-wrap: wrap; }

.btn {
  display: inline-block; padding: 13px 32px; border-radius: 999px;
  font-size: 16px; font-weight: 600; cursor: pointer; border: 1px solid transparent;
  transition: all .2s;
}
.btn-primary { background: linear-gradient(135deg, var(--c-primary), var(--c-primary-dark)); color: #fff; }
.btn-primary:hover { transform: translateY(-2px); filter: brightness(1.08); }
.btn-outline { border-color: rgba(255,255,255,.7); color: #fff; background: rgba(255,255,255,.06); }
.btn-outline:hover { background: rgba(255,255,255,.16); }

/* ---------- 区块 ---------- */
.section { padding: 72px 0; }
.section--alt { background: rgba(255,255,255,.04); border-top: 1px solid var(--c-line); border-bottom: 1px solid var(--c-line); }
.section-head { text-align: center; max-width: 700px; margin: 0 auto 44px; }
.section-head h2 { font-size: clamp(24px, 3.4vw, 34px); font-weight: 700; color: #fff; }
.section-head p { margin-top: 12px; color: rgba(255,255,255,.66); }

.grid { display: grid; gap: 24px; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.card {
  background: rgba(255,255,255,.07);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  padding: 28px;
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  transition: transform .25s, background .25s;
}
.card:hover { transform: translateY(-4px); background: rgba(255,255,255,.11); }
.card .icon {
  width: 48px; height: 48px; border-radius: 12px;
  background: rgba(255,212,160,.16); color: #ffd4a0;
  display: grid; place-items: center; font-size: 22px; font-weight: 700;
}
.card h3 { margin: 16px 0 10px; font-size: 18px; color: #fff; }
.card p { color: rgba(255,255,255,.74); font-size: 15px; }
.grid--narrow { max-width: 940px; margin: 0 auto; }

/* ---------- 联系 / 页脚 ---------- */
.contact-box {
  max-width: 520px; margin: 0 auto; text-align: center; padding: 28px;
  background: rgba(255,255,255,.07); border: 1px solid var(--c-line); border-radius: var(--radius);
}
.contact-box p { margin-bottom: 18px; color: rgba(255,255,255,.8); }
.site-footer {
  padding: 26px 0; text-align: center; color: rgba(255,255,255,.5);
  border-top: 1px solid var(--c-line); font-size: 14px;
}

/* ---------- 动效关闭（用户偏好） ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  body { background-attachment: scroll; }
}

/* ---------- 响应式 ---------- */
@media (max-width: 768px) {
  .nav-toggle { display: flex; }
  .nav-menu {
    position: absolute; top: 68px; left: 0; right: 0;
    flex-direction: column; background: rgba(10,14,30,.96);
    border-bottom: 1px solid var(--c-line);
    padding: 12px 20px; gap: 2px; display: none;
  }
  .nav-menu.open { display: flex; }
  .nav-menu a { padding: 12px 8px; }
  .hero { padding: 70px 0 90px; }
  .section { padding: 52px 0; }
}