/* ============================================================
   维谷AI 首页 · 学术化视觉（参考 subject8.3dgu.com 藏青学术风）
   Light / Dark 双主题 · 藏青深蓝 + 学术金 + 衬线标题
   ============================================================ */

:root {
  /* 品牌色 —— 学术藏青深蓝 + 学术金点缀 */
  --brand-1: #123a6b;        /* 藏青 */
  --brand-2: #1e63b8;        /* 学术蓝 */
  --brand-ink: #0a2547;      /* 更深墨蓝：标题/深底 */
  --accent: #a6791c;         /* 学术金（加重：更沉稳鲜明） */
  --accent-soft: rgba(166,121,28,.16);
  --brand-grad: linear-gradient(135deg, #123a6b 0%, #1e63b8 100%);
  --brand-grad-soft: linear-gradient(135deg, rgba(18,58,107,.08), rgba(30,99,184,.08));

  /* 浅色主题 —— 象牙白纸张感 */
  --bg: #fbfaf7;
  --bg-soft: #f4f2ec;
  --bg-elev: #ffffff;
  --text: #182338;
  --text-muted: #5a647a;
  --border: #e6e2d8;
  --border-strong: #d3cdbf;
  --shadow-sm: 0 1px 2px rgba(10,37,71,.05), 0 1px 3px rgba(10,37,71,.04);
  --shadow-md: 0 10px 30px -14px rgba(10,37,71,.22);
  --shadow-lg: 0 26px 56px -22px rgba(18,58,107,.34);
  --nav-bg: rgba(251,250,247,.80);
  --card-bg: #ffffff;

  /* 字体：衬线标题（学术感）+ 无衬线正文 */
  --font-serif: "Source Serif 4", "Noto Serif SC", Georgia, "Songti SC", "SimSun", serif;
  --font-sans: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;

  --radius: 12px;
  --radius-lg: 18px;
  --maxw: 1180px;
  --ease: cubic-bezier(.22,.61,.36,1);
}

[data-theme="dark"] {
  --brand-1: #3f7fd6;
  --brand-2: #6aa4e8;
  --brand-ink: #0a1830;
  --accent: #d8b75e;
  --accent-soft: rgba(216,183,94,.18);
  --brand-grad: linear-gradient(135deg, #1e4c86 0%, #3f7fd6 100%);
  --brand-grad-soft: linear-gradient(135deg, rgba(63,127,214,.12), rgba(106,164,232,.10));

  --bg: #0a1220;
  --bg-soft: #0f1a2c;
  --bg-elev: #101c30;
  --text: #e7ecf5;
  --text-muted: #97a3b8;
  --border: #1d2b42;
  --border-strong: #2a3c58;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.4);
  --shadow-md: 0 14px 40px -16px rgba(0,0,0,.6);
  --shadow-lg: 0 30px 70px -20px rgba(63,127,214,.4);
  --nav-bg: rgba(10,18,32,.74);
  --card-bg: #0f1a2c;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 90px; }

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  transition: background .35s var(--ease), color .35s var(--ease);
  overflow-x: hidden;
}

/* 学术衬线标题 */
.hero__title,
.section-head h2,
.feature__text h3,
.cta__inner h2 { font-family: var(--font-serif); letter-spacing: 0; }

.container { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 10px 18px; border-radius: 12px; font-weight: 600; font-size: 15px;
  cursor: pointer; border: 1px solid transparent; transition: all .2s var(--ease);
  white-space: nowrap;
}
.btn--lg { padding: 14px 26px; font-size: 16px; border-radius: 14px; }
.btn--block { width: 100%; }
.btn--primary { background: var(--brand-grad); color: #fff; box-shadow: var(--shadow-md); }
.btn--primary:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); filter: brightness(1.05); }
.btn--ghost { color: var(--text); background: transparent; }
.btn--ghost:hover { background: var(--bg-soft); }
.btn--outline { background: transparent; border-color: var(--border-strong); color: var(--text); }
.btn--outline:hover { border-color: var(--brand-1); color: var(--brand-1); background: var(--brand-grad-soft); }
.btn--light { background: #fff; color: var(--brand-1); }
.btn--light:hover { transform: translateY(-2px); }
.btn--outline-light { background: transparent; border-color: rgba(255,255,255,.5); color: #fff; }
.btn--outline-light:hover { background: rgba(255,255,255,.12); }
.btn--gold { background: var(--accent-soft); color: var(--accent); border: 1.5px solid var(--accent); font-weight: 700; }
.btn--gold:hover { background: var(--accent); color: #fff; transform: translateY(-2px); box-shadow: 0 10px 26px -10px rgba(166,121,28,.6); }

/* ---------- 公告条 ---------- */
.announce {
  background: var(--brand-grad); color: #fff; font-size: 14px;
  position: relative; z-index: 60;
}
.announce__inner { display: flex; align-items: center; gap: 10px; padding: 8px 24px; max-width: var(--maxw); margin: 0 auto; }
.announce__dot { width: 8px; height: 8px; border-radius: 50%; background: #fff; box-shadow: 0 0 0 4px rgba(255,255,255,.3); }
.announce__link { font-weight: 700; text-decoration: underline; }
.announce__close { margin-left: auto; background: none; border: none; color: #fff; font-size: 18px; cursor: pointer; line-height: 1; opacity: .8; }
.announce__close:hover { opacity: 1; }
.announce.hide { display: none; }

/* ---------- 导航 ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: var(--nav-bg);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color .3s, box-shadow .3s, background .35s;
}
.nav.scrolled { border-bottom-color: var(--border); box-shadow: var(--shadow-sm); }
.nav__inner { display: flex; align-items: center; gap: 24px; height: 66px; }
.brand { display: inline-flex; align-items: center; gap: 9px; font-weight: 800; font-size: 19px; }
.brand__logo {
  width: 34px; height: 34px; border-radius: 10px; display: grid; place-items: center;
  background: var(--brand-grad); color: #fff; font-weight: 800; font-size: 17px;
  box-shadow: var(--shadow-md);
}
.brand__logo-img {
  height: 34px; width: auto; object-fit: contain; border-radius: 6px;
}
.brand__ai { background: var(--brand-grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.nav__links { display: flex; gap: 6px; margin-left: 12px; }
.nav__links a { padding: 8px 14px; border-radius: 10px; color: var(--text-muted); font-weight: 500; font-size: 15px; transition: all .2s; }
.nav__links a:hover { color: var(--text); background: var(--bg-soft); }
.nav__actions { margin-left: auto; display: flex; align-items: center; gap: 10px; }
.icon-btn {
  width: 40px; height: 40px; border-radius: 11px; border: 1px solid var(--border);
  background: var(--bg-elev); color: var(--text); display: grid; place-items: center; cursor: pointer; transition: all .2s;
}
.icon-btn:hover { border-color: var(--brand-1); color: var(--brand-1); }
.nav__burger { display: none; }
.ico-moon { display: none; }
[data-theme="dark"] .ico-sun { display: none; }
[data-theme="dark"] .ico-moon { display: block; }

/* ---------- HERO ---------- */
.hero { position: relative; padding: 70px 0 40px; overflow: hidden; }
.hero__bg { position: absolute; inset: 0; z-index: 0; pointer-events: none; }
.blob { position: absolute; border-radius: 50%; filter: blur(70px); opacity: .5; }
.blob--1 { width: 520px; height: 520px; background: radial-gradient(circle, #5b8fd6, transparent 70%); top: -180px; right: -120px; opacity: .35; }
.blob--2 { width: 460px; height: 460px; background: radial-gradient(circle, #c9a85a, transparent 70%); bottom: -220px; left: -140px; opacity: .28; }
/* 论文网格纸底纹：细藏青网格（小格 + 每 5 格加重主线），边缘渐隐 */
.grid-overlay {
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(18,58,107,.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(18,58,107,.05) 1px, transparent 1px),
    linear-gradient(rgba(18,58,107,.10) 1px, transparent 1px),
    linear-gradient(90deg, rgba(18,58,107,.10) 1px, transparent 1px);
  background-size: 26px 26px, 26px 26px, 130px 130px, 130px 130px;
  mask-image: radial-gradient(ellipse 92% 72% at 50% 32%, #000 38%, transparent 82%);
  -webkit-mask-image: radial-gradient(ellipse 92% 72% at 50% 32%, #000 38%, transparent 82%);
  opacity: 1;
}
.hero__inner { position: relative; z-index: 1; display: grid; grid-template-columns: 1.05fr 1fr; gap: 56px; align-items: center; }

.badge {
  display: inline-flex; align-items: center; gap: 8px; padding: 6px 14px; border-radius: 999px;
  background: var(--brand-grad-soft); border: 1px solid var(--border); color: var(--brand-1);
  font-size: 13px; font-weight: 600; margin-bottom: 22px;
}
.badge__dot { width: 7px; height: 7px; border-radius: 50%; background: var(--brand-1); animation: pulse 2s infinite; }
@keyframes pulse { 0%,100%{ box-shadow:0 0 0 0 rgba(30,99,184,.5);} 50%{ box-shadow:0 0 0 6px rgba(30,99,184,0);} }

.hero__title { font-size: clamp(34px, 5vw, 54px); line-height: 1.18; font-weight: 700; letter-spacing: -.2px; margin: 0 0 20px; }
.grad-text { background: var(--brand-grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero__sub { font-size: 17px; color: var(--text-muted); max-width: 520px; margin: 0 0 30px; }
.hero__sub .hl { color: var(--brand-1); font-weight: 700; }
.hero__cta { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 26px; }
.hero__meta { display: flex; align-items: center; gap: 12px; color: var(--text-muted); font-size: 14px; }
.hero__meta strong { color: var(--text); }
.hero__avatars { display: flex; }
.hero__avatars span { width: 32px; height: 32px; border-radius: 50%; display: grid; place-items: center; background: var(--bg-soft); border: 2px solid var(--bg); margin-left: -8px; font-size: 15px; }
.hero__avatars span:first-child { margin-left: 0; }

/* 浏览器窗口示意图 */
.hero__visual { position: relative; }
.window {
  background: var(--card-bg); border: 1px solid var(--border); border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg); overflow: hidden;
}
.window__bar { display: flex; align-items: center; gap: 8px; padding: 12px 16px; border-bottom: 1px solid var(--border); background: var(--bg-soft); }
.dot { width: 11px; height: 11px; border-radius: 50%; }
.dot--r { background: #ff5f57; } .dot--y { background: #febc2e; } .dot--g { background: #28c840; }
.window__url { margin-left: 10px; font-size: 12px; color: var(--text-muted); font-family: monospace; }
.window__body { padding: 18px; }
.roadmap { width: 100%; height: auto; }
.window__chips { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 14px; }
.chip { font-size: 12px; padding: 5px 11px; border-radius: 999px; background: var(--brand-grad-soft); color: var(--brand-1); border: 1px solid var(--border); font-weight: 600; }
.float-card {
  position: absolute; background: var(--card-bg); border: 1px solid var(--border);
  padding: 10px 14px; border-radius: 14px; font-size: 13px; font-weight: 600; box-shadow: var(--shadow-md);
  animation: float 4s ease-in-out infinite;
}
.float-card--1 { top: -18px; left: -24px; }
.float-card--2 { bottom: -16px; right: -16px; animation-delay: 1.5s; color: var(--brand-1); }
@keyframes float { 0%,100%{ transform: translateY(0);} 50%{ transform: translateY(-10px);} }

/* ---------- 线性图标（藏青描边，统一学术主题） ---------- */
.ic { width: 28px; height: 28px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.ic--sm { width: 16px; height: 16px; stroke-width: 2; }
.ic--xs { width: 18px; height: 18px; }
.float-card .ic { vertical-align: -3px; margin-right: 6px; }
.hero__avatars .ic { width: 16px; height: 16px; }

/* ---------- 数据条 ---------- */
.stats { padding: 36px 0; }
.stats__grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 18px; background: var(--bg-soft); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 30px 24px; }
.stat { text-align: center; }
.stat__num { font-size: clamp(30px,4vw,44px); font-weight: 800; background: var(--brand-grad); -webkit-background-clip: text; background-clip: text; color: transparent; line-height: 1; }
.stat__unit { font-size: 16px; -webkit-text-fill-color: var(--brand-1); margin-left: 2px; }
.stat__label { color: var(--text-muted); font-size: 14px; margin-top: 8px; }

/* ---------- 信任 logo ---------- */
.trust { padding: 30px 0 10px; }
.trust__title { text-align: center; color: var(--text-muted); font-size: 14px; margin-bottom: 20px; letter-spacing: .3px; }
.trust__logos { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; }
.logo-chip {
  padding: 9px 18px; border-radius: 12px; border: 1px solid var(--border); background: var(--card-bg);
  color: var(--text-muted); font-weight: 600; font-size: 14px; transition: all .2s;
}
.logo-chip:hover { border-color: var(--brand-1); color: var(--brand-1); transform: translateY(-2px); }

/* ---------- 区块标题 ---------- */
.section-head { text-align: center; max-width: 680px; margin: 0 auto 50px; }
.section-head--left { text-align: left; margin: 0; }
.eyebrow { display: inline-flex; align-items: center; gap: 10px; font-size: 12px; font-weight: 700; letter-spacing: 2px; text-transform: uppercase; color: var(--accent); margin-bottom: 14px; }
.eyebrow::before, .eyebrow::after { content: ""; width: 26px; height: 2px; background: var(--accent); opacity: .85; }
.section-head--left .eyebrow::after { display: none; }
.section-head h2 { font-size: clamp(26px,3.4vw,38px); font-weight: 700; letter-spacing: -.2px; margin: 0 0 14px; line-height: 1.25; }
.section-head p { color: var(--text-muted); font-size: 16px; margin: 0; }

/* ---------- 核心功能 ---------- */
.features { padding: 80px 0; }
.feature { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: center; padding: 40px 0; }
.feature--reverse .feature__media { order: 2; }
.feature__media {
  background: var(--bg-soft); border: 1px solid var(--border); border-radius: var(--radius-lg);
  padding: 32px; position: relative; overflow: hidden;
}
.feature__media::before { content:""; position:absolute; inset:0; background: var(--brand-grad-soft); opacity:.5; }
.feature__icon {
  position: relative; width: 60px; height: 60px; border-radius: 14px; display: grid; place-items: center;
  background: var(--brand-grad-soft); border: 1px solid var(--border-strong); color: var(--brand-1); margin-bottom: 22px;
}
.feature__icon .ic { width: 32px; height: 32px; }
.feature__points { position: relative; list-style: none; margin: 0; padding: 0; display: grid; gap: 12px; }
.feature__points li { padding-left: 30px; position: relative; color: var(--text); font-weight: 500; }
.feature__points li::before { content: "✓"; position: absolute; left: 0; top: 0; width: 20px; height: 20px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); display: grid; place-items: center; font-size: 12px; font-weight: 800; }
.feature__no { font-family: var(--font-serif); font-style: italic; font-size: 46px; font-weight: 700; color: var(--accent); opacity: .88; line-height: 1; display: block; margin-bottom: 8px; }
.feature__text h3 { font-size: 26px; font-weight: 700; margin: 0 0 14px; }
.feature__text p { color: var(--text-muted); font-size: 16px; margin: 0 0 20px; }
.link-arrow { color: var(--brand-1); font-weight: 700; transition: gap .2s; }
.link-arrow:hover { text-decoration: underline; }

/* ---------- 产品模块 ---------- */
.modules { padding: 80px 0; background: var(--bg-soft); }
.cards { display: grid; grid-template-columns: repeat(4,1fr); gap: 20px; }
.card {
  background: var(--card-bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px;
  transition: all .25s var(--ease); position: relative; display: flex; flex-direction: column;
}
.card:hover { transform: translateY(-6px); border-color: var(--brand-1); box-shadow: var(--shadow-md); }
.card__top {
  width: 50px; height: 50px; border-radius: 12px; display: grid; place-items: center; color: var(--brand-1);
  background: var(--brand-grad-soft); border: 1px solid var(--border); margin-bottom: 16px;
}
.card__top .ic { width: 26px; height: 26px; }
.card h3 { font-size: 17px; font-weight: 700; margin: 0 0 8px; }
.card p { color: var(--text-muted); font-size: 14px; margin: 0; flex: 1; }
.card__tag { align-self: flex-start; margin-top: 14px; font-size: 11px; font-weight: 700; padding: 3px 10px; border-radius: 999px; background: var(--brand-grad); color: #fff; }

/* ---------- 使用流程 ---------- */
.how { padding: 80px 0; }
.steps { display: grid; grid-template-columns: repeat(4,1fr); gap: 22px; counter-reset: step; }
.step { position: relative; padding: 28px 22px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--card-bg); }
.step::after { content:""; position:absolute; top: 46px; right: -22px; width: 22px; height: 2px; background: var(--border-strong); }
.step:last-child::after { display: none; }
.step__no {
  width: 40px; height: 40px; border-radius: 12px; background: var(--brand-grad); color: #fff; font-weight: 800;
  display: grid; place-items: center; margin-bottom: 16px; box-shadow: var(--shadow-md);
}
.step h3 { font-size: 17px; margin: 0 0 8px; }
.step p { color: var(--text-muted); font-size: 14px; margin: 0; }

/* ---------- 用户评价 ---------- */
.cases { padding: 80px 0; background: var(--bg-soft); }
.quotes { display: grid; grid-template-columns: repeat(2,1fr); gap: 22px; }
.quote { position: relative; margin: 0; background: var(--card-bg); border: 1px solid var(--border); border-left: 4px solid var(--accent); border-radius: var(--radius); padding: 30px 28px 26px; transition: all .25s; }
.quote:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.quote::before { content: "\201C"; position: absolute; top: 6px; right: 20px; font-family: var(--font-serif); font-size: 64px; line-height: 1; color: var(--accent); opacity: .32; }
.quote blockquote { position: relative; margin: 0 0 20px; font-family: var(--font-serif); font-style: italic; font-size: 16.5px; line-height: 1.75; color: var(--text); }
.quote figcaption { display: flex; align-items: center; gap: 12px; }
.quote__avatar { width: 44px; height: 44px; border-radius: 50%; background: var(--brand-grad-soft); display: grid; place-items: center; font-size: 22px; }
.quote figcaption strong { display: block; font-size: 15px; }
.quote figcaption span { color: var(--text-muted); font-size: 13px; }

/* ---------- 定价 ---------- */
.pricing { padding: 80px 0; }
.plans { display: grid; grid-template-columns: repeat(4,1fr); gap: 20px; }
.plans--4 { max-width: 1100px; margin: 0 auto; }
.plans--5 { max-width: 1200px; margin: 0 auto; grid-template-columns: repeat(5,1fr); }
.plan { position: relative; border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 34px 24px; background: var(--card-bg); }
.plan--featured { border-color: var(--brand-1); box-shadow: var(--shadow-lg); background: var(--brand-grad-soft); }
.plan--free { border-color: var(--border-strong); background: var(--bg-soft); }
.plan__badge { position: absolute; top: -13px; left: 24px; background: var(--brand-grad); color: #fff; font-size: 12px; font-weight: 700; padding: 4px 14px; border-radius: 999px; }
.plan__badge--free { background: linear-gradient(135deg, #5a647a, #7b8599); }
.plan__name { font-size: 20px; margin: 0 0 8px; }
.plan__price { font-size: 38px; font-weight: 800; margin-bottom: 22px; }
.plan__price span { font-size: 14px; font-weight: 500; color: var(--text-muted); }
.plan__list { list-style: none; margin: 0 0 26px; padding: 0; display: grid; gap: 12px; }
.plan__list li { padding-left: 28px; position: relative; color: var(--text); }
.plan__list li::before { content:"✓"; position:absolute; left:0; top:0; width:20px; height:20px; border-radius:50%; background: var(--brand-grad); color:#fff; display:grid; place-items:center; font-size:11px; font-weight:800; }
.pricing__note { text-align: center; color: var(--text-muted); font-size: 13px; margin-top: 26px; }

.plan__dur {
  font-size: 14px; font-weight: 600; color: var(--brand-1);
  margin-bottom: 4px; display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
}
.dur-tag {
  display: inline-flex; align-items: center;
  background: var(--brand-grad-soft); color: var(--brand-1);
  border: 1px solid var(--border); padding: 3px 10px;
  border-radius: 8px; font-size: 13.5px; font-weight: 700; letter-spacing: .2px;
}
.dur-tag--year { background: rgba(166,121,28,.12); color: var(--accent); border-color: rgba(166,121,28,.25); }
.dur-tag--long { background: var(--brand-grad); color: #fff; border-color: transparent; }
.plan__dur small {
  font-size: 11.5px; font-weight: 500; color: var(--text-muted);
}
.plan__orig {
  font-size: 13px; color: var(--text-muted); margin-bottom: 18px;
}
.plan__orig::before { content: ""; display: inline-block; width: 12px; height: 1px; background: var(--text-muted); vertical-align: middle; margin-right: 6px; opacity: .5; }

/* ---------- 会员服务 ---------- */
.member { padding: 80px 0; background: var(--bg-soft); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.member__grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 12px; }
.member__item {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  padding: 15px 18px; border: 1px solid var(--border); border-radius: 12px;
  background: var(--card-bg); color: var(--text); text-decoration: none;
  transition: all .2s var(--ease);
}
.member__item:hover { border-color: var(--brand-1); transform: translateY(-2px); box-shadow: var(--shadow-sm); }
.member__name { font-weight: 600; font-size: 15px; }
.member__ver { font-size: 12px; color: var(--text-muted); flex-shrink: 0; }
.member__item--more { grid-column: 1 / -1; justify-content: center; gap: 8px; background: var(--brand-grad); color: #fff; border: none; font-weight: 700; }
.member__item--more .member__ver { color: rgba(255,255,255,.85); }
.member__item--more:hover { box-shadow: var(--shadow-md); }

.member__note { display: grid; grid-template-columns: repeat(3,1fr); gap: 16px; margin-top: 28px; }
.member__tip {
  display: flex; gap: 12px; align-items: flex-start; padding: 16px 18px;
  border: 1px dashed var(--border-strong); border-radius: 12px; background: var(--card-bg);
}
.member__tip .ic { width: 22px; height: 22px; flex-shrink: 0; color: var(--accent); margin-top: 2px; }
.member__tip p { margin: 0; font-size: 14px; line-height: 1.6; }
.member__tip strong { color: var(--text); }
.member__tip a { color: var(--brand-1); font-weight: 600; text-decoration: none; }
.member__tip a:hover { text-decoration: underline; }

/* ---------- FAQ ---------- */
.faq { padding: 80px 0; }
.faq__wrap { display: grid; grid-template-columns: 0.8fr 1.2fr; gap: 50px; align-items: start; }
.faq__list { display: grid; gap: 12px; }
.faq__item { border: 1px solid var(--border); border-radius: var(--radius); background: var(--card-bg); overflow: hidden; }
.faq__item summary { list-style: none; cursor: pointer; padding: 18px 22px; font-weight: 600; font-size: 16px; display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.faq__item summary::-webkit-details-marker { display: none; }
.faq__item summary::after { content: "+"; font-size: 22px; color: var(--brand-1); transition: transform .25s; }
.faq__item[open] summary::after { transform: rotate(45deg); }
.faq__body { padding: 0 22px 20px; color: var(--text-muted); font-size: 15px; }

/* ---------- 末尾 CTA ---------- */
.cta { padding: 40px 0 90px; }
.cta__inner { position: relative; text-align: center; padding: 70px 24px; border-radius: var(--radius-lg); overflow: hidden; color: #fff; background: #0b1020; }
.cta__bg { position: absolute; inset: 0; background: var(--brand-grad); opacity: .9; }
.cta__bg::after { content:""; position:absolute; inset:0; background-image: radial-gradient(circle at 20% 20%, rgba(255,255,255,.18), transparent 40%), radial-gradient(circle at 80% 70%, rgba(255,255,255,.14), transparent 40%); }
.cta__inner h2, .cta__inner p, .cta__btns { position: relative; z-index: 1; }
.cta__inner h2 { font-size: clamp(26px,3.5vw,40px); font-weight: 800; margin: 0 0 12px; }
.cta__inner p { font-size: 17px; opacity: .9; margin: 0 0 30px; }
.cta__btns { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }

/* ---------- 页脚 ---------- */
.footer { border-top: 1px solid var(--border); background: var(--bg-soft); padding: 56px 0 28px; }
.footer__grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr; gap: 32px; }
.footer__brand p { color: var(--text-muted); font-size: 14px; max-width: 280px; margin: 14px 0 0; }
.footer__col h4 { font-size: 15px; margin: 0 0 14px; }
.footer__col a { display: block; color: var(--text-muted); font-size: 14px; padding: 5px 0; transition: color .2s; }
.footer__col a:hover { color: var(--brand-1); }
.footer__wechat { display: block; color: var(--text-muted); font-size: 14px; padding: 5px 0; transition: color .2s; }
.footer__qrcode { width: 96px; height: 96px; margin-top: 8px; border-radius: 6px; border: 1px solid var(--border); }
.footer__bottom { display: flex; justify-content: space-between; align-items: center; margin-top: 40px; padding-top: 22px; border-top: 1px solid var(--border); color: var(--text-muted); font-size: 13px; flex-wrap: wrap; gap: 10px; }
.footer__beian { letter-spacing: .2px; }

/* ---------- 滚动渐显 ---------- */
.reveal { opacity: 0; transform: translateY(26px); transition: opacity .7s var(--ease), transform .7s var(--ease); }
.reveal.in { opacity: 1; transform: none; }

/* ---------- 学术1.0 主推 ---------- */
.spotlight { padding: 64px 0 56px; position: relative;
  background: linear-gradient(180deg, var(--bg-soft), var(--bg));
  border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.spotlight--alt { background: var(--bg); border-top: none; }
.spotlight__inner { max-width: 1080px; margin: 0 auto; }
.spotlight__head { text-align: center; max-width: 760px; margin: 0 auto 44px; }
.spotlight__title { font-family: var(--font-serif); font-size: clamp(28px,3.6vw,42px); font-weight: 700; letter-spacing: -.2px; margin: 12px 0 16px; }
.spotlight__sub { color: var(--text-muted); font-size: 17px; line-height: 1.75; margin: 0 0 26px; }
.spotlight__sub strong { color: var(--brand-1); font-weight: 700; }
.spotlight__grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 20px; }
.scard { background: var(--card-bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 26px 22px; transition: all .25s var(--ease); position: relative; overflow: hidden; }
.scard::before { content:""; position: absolute; top: 0; left: 0; right: 0; height: 3px; background: linear-gradient(90deg, var(--brand-1), var(--accent)); opacity: 0; transition: opacity .25s; }
.scard:hover { transform: translateY(-6px); box-shadow: var(--shadow-md); border-color: var(--brand-1); }
.scard:hover::before { opacity: 1; }
.scard__ico { width: 50px; height: 50px; border-radius: 13px; display: grid; place-items: center; background: var(--brand-grad-soft); border: 1px solid var(--border); margin-bottom: 16px; color: var(--brand-1); }
.scard__ico .ic { width: 26px; height: 26px; }
.scard h3 { font-size: 19px; font-weight: 700; margin: 0 0 8px; }
.scard__num { color: var(--accent); font-weight: 700; font-size: 13.5px; margin: 0 0 10px; }
.scard__desc { color: var(--text-muted); font-size: 14px; line-height: 1.7; margin: 0; }

/* ---------- 维谷 AIGC 降率工作台 ---------- */
.aigc__lead { display: grid; grid-template-columns: 1.05fr 1fr; gap: 40px; align-items: center; margin-bottom: 52px; }
.aigc__lead-text h3 { font-family: var(--font-serif); font-size: clamp(22px,2.6vw,30px); font-weight: 700; margin: 0 0 16px; line-height: 1.3; }
.aigc__lead-text p { color: var(--text-muted); font-size: 16px; line-height: 1.9; margin: 0 0 16px; }
.aigc__lead-text .btn { margin-top: 6px; }
.aigc__lead-card { background: var(--card-bg); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 30px 30px 26px; box-shadow: var(--shadow-md); }
.aigc__lead-card__title { font-weight: 700; font-size: 18px; margin: 0 0 14px; color: var(--brand-1); }
.aigc__lead-card__desc { color: var(--text-muted); font-size: 15px; line-height: 1.85; margin: 0 0 12px; }
.aigc__lead-card__desc a { color: var(--brand-1); font-weight: 700; }
.aigc__features { display: grid; grid-template-columns: repeat(3,1fr); gap: 20px; margin-bottom: 46px; }
.aigc__who { text-align: center; margin-bottom: 34px; }
.aigc__who-label { display: block; font-weight: 700; font-size: 16px; margin-bottom: 16px; }
.aigc__tags { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; }
.aigc__tag { font-size: 14px; padding: 9px 18px; border-radius: 999px; background: var(--brand-grad-soft); border: 1px solid var(--border); color: var(--brand-1); font-weight: 600; }
.aigc__note { background: var(--brand-grad-soft); border: 1px solid var(--border); border-left: 4px solid var(--accent); border-radius: var(--radius); padding: 22px 26px; margin-bottom: 38px; color: var(--text-muted); font-size: 15px; line-height: 1.85; }
.aigc__note strong { color: var(--accent); }
.aigc__cta { text-align: center; background: linear-gradient(135deg, rgba(18,58,107,.05), rgba(216,183,94,.08)); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 38px 28px; }
.aigc__cta p { font-size: 17px; line-height: 1.8; margin: 0 0 20px; color: var(--text); }

/* ---------- 响应式 ---------- */
@media (max-width: 980px) {
  .hero__inner { grid-template-columns: 1fr; gap: 40px; }
  .hero__visual { max-width: 520px; }
  .cards { grid-template-columns: repeat(2,1fr); }
  .steps { grid-template-columns: repeat(2,1fr); }
  .step::after { display: none; }
  .faq__wrap { grid-template-columns: 1fr; gap: 30px; }
  .plans--4 { grid-template-columns: repeat(2,1fr); }
  .plans--5 { grid-template-columns: repeat(3,1fr); }
  .member__grid, .member__note { grid-template-columns: repeat(2,1fr); }
  .spotlight__grid { grid-template-columns: repeat(2,1fr); }
  .aigc__lead { grid-template-columns: 1fr; gap: 28px; }
  .aigc__features { grid-template-columns: repeat(2,1fr); }
  .plan__tiers { grid-template-columns: repeat(4,1fr); }
}
@media (max-width: 760px) {
  .nav__links { display: none; }
  .nav__links.open {
    display: flex; flex-direction: column; position: absolute; top: 66px; left: 0; right: 0;
    background: var(--nav-bg); backdrop-filter: blur(14px); padding: 14px 24px; gap: 4px;
    border-bottom: 1px solid var(--border); box-shadow: var(--shadow-md);
  }
  .nav__links.open a { padding: 12px 14px; }
  .nav__burger { display: grid; }
  .nav__actions .btn--ghost { display: none; }
  .stats__grid { grid-template-columns: repeat(2,1fr); }
  .feature { grid-template-columns: 1fr; gap: 28px; }
  .feature--reverse .feature__media { order: 0; }
  .quotes, .plans, .cards { grid-template-columns: 1fr; }
  .plans--5 { grid-template-columns: 1fr; }
  .member__grid, .member__note { grid-template-columns: 1fr; }
  .spotlight__grid { grid-template-columns: 1fr; }
  .aigc__features { grid-template-columns: 1fr; }
  .spotlight__head { text-align: left; }
  .plan__tiers { grid-template-columns: repeat(2,1fr); }
  .footer__grid { grid-template-columns: 1fr 1fr; }
  .footer__brand { grid-column: 1 / -1; }
  .footer__bottom { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 460px) {
  .footer__grid { grid-template-columns: 1fr; }
  .stats__grid { grid-template-columns: 1fr 1fr; }
}

/* 尊重减少动效偏好 */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .reveal { opacity: 1; transform: none; }
}