/* ============================================================
   AI圆桌 官网落地页 — styles.css
   纯静态站点，自包含，不访问外网。
   ============================================================ */

/* ── 设计 token ── */
:root {
  --brand: #005185;
  --accent: #EF684C;
  --gold: #B0904F;
  --ink: #0A1629;
  --ink2: #1A3357;
  --body: #3A3733;
  --muted: #5A6672;
  --bg: #F5F5F5;
  --cream: #F3F1EC;
  --card: #FFFFFF;
  --hair: rgba(0, 0, 0, 0.12);
  --line: rgba(0, 0, 0, 0.06);
  --title-grad: linear-gradient(180deg, #DCE3EA 0%, #D2DAE2 100%);
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.10);

  /* 系统自带宋体，不下载字体文件，零流量 */
  --serif: 'Songti SC', 'STSong', 'Source Han Serif CN', 'Noto Serif CJK SC',
           'SimSun', 'NSimSun', 'FangSong', serif;
  --sans: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Hiragino Sans GB',
          'Noto Sans SC', 'Microsoft YaHei', sans-serif;

  --r-sm: 8px;
  --r-md: 12px;
  --r-lg: 16px;
  --pill: 99px;
  --maxw: 1180px;
}

/* ── reset ── */
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; overflow-x: hidden; }
body {
  font-family: var(--sans);
  color: var(--body);
  background: var(--bg);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
a { color: inherit; text-decoration: none; }
em { font-style: normal; color: var(--brand); font-weight: 600; }
h1, h2, h3 { font-family: var(--serif); color: var(--ink); font-weight: 600; }

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

/* ── 按钮 ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 46px;
  padding: 0 26px;
  border-radius: var(--pill);
  font-size: 15px;
  font-weight: 500;
  letter-spacing: 0.5px;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform .18s ease, box-shadow .18s ease, background .18s ease, color .18s ease;
  white-space: nowrap;
}
.btn--solid {
  background: var(--brand);
  color: #fff;
  box-shadow: 0 4px 16px rgba(0, 81, 133, 0.28);
}
.btn--solid:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 22px rgba(0, 81, 133, 0.34);
}
.btn--ghost {
  background: #fff;
  color: var(--brand);
  border-color: rgba(0, 81, 133, 0.30);
}
.btn--ghost:hover { transform: translateY(-2px); border-color: var(--brand); }
.btn--sm { height: 38px; padding: 0 18px; font-size: 14px; }
.btn--lg { height: 54px; padding: 0 36px; font-size: 16.5px; }

/* ── 顶部导航 ── */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(245, 245, 245, 0.72);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color .3s ease, background .3s ease;
}
.nav.is-scrolled {
  background: rgba(245, 245, 245, 0.88);
  border-bottom-color: var(--line);
}
.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand { display: inline-flex; align-items: center; gap: 9px; }
.brand__mark { display: inline-flex; color: var(--brand); }
.brand__name {
  font-family: var(--serif);
  font-size: 19px;
  font-weight: 600;
  color: var(--ink2);
  letter-spacing: 1px;
}
.nav__links { display: flex; align-items: center; gap: 30px; }
.nav__links > a:not(.btn) {
  font-size: 15px;
  color: var(--muted);
  transition: color .18s ease;
}
.nav__links > a:not(.btn):hover { color: var(--ink2); }
.nav__cta { color: #fff; }

/* 汉堡按钮 */
.nav__toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px; height: 40px;
  background: none; border: none; cursor: pointer;
}
.nav__toggle span {
  display: block;
  width: 22px; height: 2px;
  background: var(--ink2);
  border-radius: 2px;
  transition: transform .25s ease, opacity .2s ease;
}
.nav__toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav__toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav__toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ── 通用区块 ── */
.section { padding: 92px 0; }
.section--alt { background: var(--cream); }

/* 分区标题（宋体居中 + 两侧细线，复刻 SummaryView） */
.sec-title {
  display: flex;
  align-items: center;
  gap: 18px;
  justify-content: center;
  margin-bottom: 14px;
}
.sec-title__line { flex: 1; max-width: 120px; height: 1px; background: var(--hair); }
.sec-title h2 {
  font-size: 27px;
  letter-spacing: 4px;
  color: var(--ink);
  white-space: nowrap;
}
.sec-lede {
  text-align: center;
  font-size: 16px;
  color: var(--muted);
  max-width: 620px;
  margin: 0 auto 52px;
  line-height: 1.8;
}

/* ============================================================
   Hero
   ============================================================ */
.hero {
  padding: 132px 0 84px;
  background:
    radial-gradient(1100px 520px at 78% -8%, rgba(0, 81, 133, 0.08), transparent 60%),
    radial-gradient(760px 460px at 6% 22%, rgba(239, 104, 76, 0.06), transparent 60%),
    var(--bg);
}
.hero__inner {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  align-items: center;
  gap: 56px;
}
.hero__eyebrow {
  font-size: 14px;
  letter-spacing: 2px;
  color: var(--gold);
  font-weight: 500;
  margin-bottom: 18px;
}
.hero__title {
  font-size: 52px;
  line-height: 1.28;
  color: var(--ink);
  letter-spacing: 1px;
}
.hero__sub {
  margin: 26px 0 34px;
  font-size: 17.5px;
  line-height: 1.9;
  color: var(--body);
  max-width: 480px;
}
.hero__actions { display: flex; gap: 14px; flex-wrap: wrap; }
.hero__note {
  margin-top: 22px;
  font-size: 13px;
  color: var(--muted);
  letter-spacing: 0.3px;
}

/* 纯 CSS 圆桌主视觉 */
.hero__stage { display: flex; justify-content: center; }
.stage {
  position: relative;
  width: 420px;
  height: 420px;
  max-width: 100%;
}
.stage__center {
  position: absolute;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  width: 208px;
  padding: 22px 20px;
  background: var(--title-grad);
  border-radius: var(--r-lg);
  box-shadow: var(--shadow-lg);
  text-align: center;
  z-index: 3;
}
.stage__q-label {
  display: block;
  font-size: 12px;
  color: #5A6672;
  letter-spacing: 1px;
  margin-bottom: 10px;
}
.stage__q-topic {
  display: block;
  font-family: var(--serif);
  font-size: 18px;
  font-weight: 600;
  color: #26303B;
  line-height: 1.5;
}
.orbit { position: absolute; inset: 0; animation: spin 46s linear infinite; }
.seat {
  position: absolute;
  top: 50%; left: 50%;
  width: 0; height: 0;
}
.seat .av { animation: spin-rev 46s linear infinite; }
.seat--1 { transform: translate(-50%, -50%) translateY(-186px); }
.seat--2 { transform: translate(-50%, -50%) translate(161px, -93px); }
.seat--3 { transform: translate(-50%, -50%) translate(161px, 93px); }
.seat--4 { transform: translate(-50%, -50%) translateY(186px); }
.seat--5 { transform: translate(-50%, -50%) translate(-161px, 93px); }
.seat--6 { transform: translate(-50%, -50%) translate(-161px, -93px); }

/* 人格头像（色环 + 首字） */
.av {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px; height: 56px;
  margin: -28px 0 0 -28px;
  border-radius: 50%;
  background: var(--c, var(--brand));
  color: #fff;
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 600;
  box-shadow: 0 3px 12px rgba(0, 0, 0, 0.16);
  border: 2px solid #fff;
}
.av--host { background: var(--c, var(--accent)); }

/* 金句 chip */
.chip {
  position: absolute;
  max-width: 184px;
  padding: 9px 14px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  box-shadow: var(--shadow);
  font-family: var(--serif);
  font-size: 12.5px;
  line-height: 1.65;
  color: #2D2A26;
  z-index: 4;
}
.chip::before {
  content: '';
  position: absolute;
  left: 14px;
  top: -3px;
  width: 16px; height: 3px;
  background: var(--gold);
  border-radius: 2px;
}
.chip--a { top: 6px; left: -14px; animation: floatY 6s ease-in-out infinite; }
.chip--b { bottom: 10px; right: -10px; animation: floatY 7s ease-in-out infinite 1s; }

/* ============================================================
   它是什么 / 三步
   ============================================================ */
.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}
.step {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  padding: 32px 28px;
  box-shadow: var(--shadow);
}
.step__num {
  display: block;
  font-family: var(--serif);
  font-size: 30px;
  font-weight: 600;
  color: var(--gold);
  line-height: 1;
  margin-bottom: 16px;
}
.step__title { font-size: 20px; color: var(--ink2); margin-bottom: 10px; }
.step__desc { font-size: 14.5px; color: var(--muted); line-height: 1.8; }

/* ============================================================
   核心特性
   ============================================================ */
.features {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.feat {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  padding: 30px 24px;
  box-shadow: var(--shadow);
  transition: transform .2s ease, box-shadow .2s ease;
}
.feat:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.feat__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 50px; height: 50px;
  border-radius: 14px;
  background: rgba(0, 81, 133, 0.08);
  color: var(--brand);
  margin-bottom: 18px;
}
.feat__icon svg { width: 26px; height: 26px; }
.feat__title { font-size: 18px; color: var(--ink2); margin-bottom: 10px; }
.feat__desc { font-size: 14px; color: var(--muted); line-height: 1.8; }

/* ============================================================
   认知提升
   ============================================================ */
.cognition {
  display: grid;
  grid-template-columns: 1fr 0.86fr;
  gap: 44px;
  align-items: start;
}
.shifts { list-style: none; display: flex; flex-direction: column; gap: 14px; }
.shift {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  padding: 22px 24px;
  box-shadow: var(--shadow);
  display: grid;
  grid-template-columns: auto auto auto;
  align-items: center;
  gap: 14px;
}
.shift__from {
  font-family: var(--serif);
  font-size: 18px;
  color: var(--muted);
  text-decoration: line-through;
  text-decoration-color: rgba(0, 0, 0, 0.2);
}
.shift__arrow { color: var(--gold); font-size: 20px; }
.shift__to {
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 600;
  color: var(--brand);
}
.shift__desc {
  grid-column: 1 / -1;
  font-size: 13.5px;
  color: var(--muted);
  line-height: 1.7;
  margin-top: 4px;
}

/* 总结卡片预览（复刻 SummaryView 编辑感） */
.summary-preview {
  background: var(--cream);
  border-radius: var(--r-lg);
  padding: 22px;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--line);
}
.sp__titleblock {
  background: var(--title-grad);
  border-radius: var(--r-md);
  padding: 22px 18px 18px;
  text-align: center;
  margin-bottom: 8px;
}
.sp__topic { font-size: 20px; color: #26303B; line-height: 1.4; }
.sp__meta { font-size: 12px; color: #5A6672; margin-top: 10px; letter-spacing: 0.5px; }
.sp__sec {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 24px 0 14px;
}
.sp__line { flex: 1; height: 1px; background: var(--hair); }
.sp__sectitle {
  font-family: var(--serif);
  font-size: 16px;
  font-weight: 600;
  color: var(--ink);
  letter-spacing: 2px;
  white-space: nowrap;
}
.sp__points { display: flex; flex-direction: column; }
.sp__point {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 11px 0;
  border-bottom: 1px solid var(--hair);
}
.sp__point:last-child { border-bottom: none; }
.sp__num {
  font-family: var(--serif);
  font-size: 17px;
  font-weight: 600;
  color: var(--gold);
  flex-shrink: 0;
  min-width: 24px;
}
.sp__ptext { font-size: 14px; color: var(--body); line-height: 1.65; }
.sp__quote {
  background: #fff;
  border-radius: var(--r-md);
  border: 1px solid rgba(0, 0, 0, 0.05);
  padding: 4px 18px 16px;
}
.sp__mark {
  display: block;
  font-family: var(--serif);
  font-size: 40px;
  color: var(--gold);
  line-height: 1;
  height: 24px;
  opacity: 0.85;
}
.sp__qtext {
  font-family: var(--serif);
  font-size: 15.5px;
  color: #2D2A26;
  line-height: 1.9;
  margin-bottom: 12px;
}
.sp__by { display: flex; align-items: center; gap: 7px; }
.sp__dot { width: 6px; height: 6px; border-radius: 50%; flex-shrink: 0; }
.sp__speaker { font-size: 12.5px; color: var(--gold); letter-spacing: 0.3px; }

/* ============================================================
   精选圆桌
   ============================================================ */
.topics {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}
.topic {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  padding: 26px 24px;
  box-shadow: var(--shadow);
  transition: transform .2s ease, box-shadow .2s ease;
}
.topic:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.topic__meta {
  font-size: 12px;
  color: rgba(0, 0, 0, 0.3);
  letter-spacing: 0.3px;
  margin-bottom: 2px;
}
.topic__title { font-size: 19px; color: var(--ink2); line-height: 1.45; margin-bottom: 12px; }
.topic__opening {
  font-size: 13.5px;
  color: rgba(0, 0, 0, 0.5);
  line-height: 1.7;
  margin-bottom: 18px;
}
.topic__guests { display: flex; align-items: center; gap: 0; flex-wrap: wrap; }
.av--sm {
  width: 30px; height: 30px;
  margin: 0 -6px 0 0;
  font-size: 13px;
  border: 2px solid #fff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.12);
}
.topic__guesttext {
  margin-left: 14px;
  font-size: 13px;
  color: rgba(0, 0, 0, 0.5);
  letter-spacing: 0.5px;
}

/* ============================================================
   结尾 CTA
   ============================================================ */
.cta { padding: 24px 0 96px; }
.cta__inner {
  background:
    radial-gradient(600px 300px at 80% 0%, rgba(239, 104, 76, 0.10), transparent 60%),
    var(--cream);
  border-radius: 28px;
  padding: 72px 32px;
  text-align: center;
  box-shadow: var(--shadow);
}
.cta__title { font-size: 34px; color: var(--ink); letter-spacing: 1px; }
.cta__sub {
  font-size: 16.5px;
  color: var(--muted);
  margin: 18px 0 32px;
  line-height: 1.8;
}

/* ============================================================
   页脚
   ============================================================ */
.footer {
  background: #fff;
  border-top: 1px solid var(--line);
  padding: 52px 0 28px;
}
.footer__inner {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 40px;
  flex-wrap: wrap;
}
.brand--footer { margin-bottom: 14px; }
.brand--footer .brand__mark { color: var(--brand); }
.footer__tag { font-size: 13.5px; color: var(--muted); max-width: 280px; line-height: 1.7; }
.footer__links { display: flex; flex-wrap: wrap; gap: 14px 26px; align-items: center; }
.footer__links a {
  font-size: 14px;
  color: var(--muted);
  transition: color .18s ease;
}
.footer__links a:hover { color: var(--brand); }
.footer__bottom {
  margin-top: 36px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
  font-size: 12.5px;
  color: var(--muted);
}

/* ============================================================
   滚动入场动画
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity .7s cubic-bezier(.2, .7, .2, 1), transform .7s cubic-bezier(.2, .7, .2, 1);
  will-change: opacity, transform;
}
.reveal.is-visible { opacity: 1; transform: none; }

@keyframes spin { to { transform: rotate(360deg); } }
@keyframes spin-rev { to { transform: rotate(-360deg); } }
@keyframes floatY {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

@media (prefers-reduced-motion: reduce) {
  .orbit, .seat .av, .chip { animation: none !important; }
  .reveal { transition: none; opacity: 1; transform: none; }
  html { scroll-behavior: auto; }
}

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1024px) {
  .features { grid-template-columns: repeat(2, 1fr); }
  .hero__title { font-size: 44px; }
}

@media (max-width: 768px) {
  .container { padding: 0 20px; }
  .section { padding: 64px 0; }
  .hero { padding: 104px 0 56px; }

  /* 导航折叠 */
  .nav__toggle { display: flex; }
  .nav__links {
    position: fixed;
    top: 64px; left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: rgba(245, 245, 245, 0.97);
    backdrop-filter: saturate(180%) blur(14px);
    -webkit-backdrop-filter: saturate(180%) blur(14px);
    border-bottom: 1px solid var(--line);
    padding: 8px 20px 20px;
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: opacity .22s ease, transform .22s ease;
  }
  .nav__links.is-open { transform: none; opacity: 1; pointer-events: auto; }
  .nav__links > a:not(.btn) {
    padding: 14px 4px;
    border-bottom: 1px solid var(--line);
    font-size: 16px;
  }
  .nav__cta { margin-top: 16px; align-self: flex-start; }

  /* Hero 单列 */
  .hero__inner { grid-template-columns: 1fr; gap: 48px; text-align: center; }
  .hero__title { font-size: 38px; }
  .hero__sub { margin-left: auto; margin-right: auto; }
  .hero__actions { justify-content: center; }
  .stage { width: 340px; height: 340px; }
  .stage__center { width: 176px; padding: 18px 16px; }
  .stage__q-topic { font-size: 16px; }
  .seat--1 { transform: translate(-50%, -50%) translateY(-150px); }
  .seat--2 { transform: translate(-50%, -50%) translate(130px, -75px); }
  .seat--3 { transform: translate(-50%, -50%) translate(130px, 75px); }
  .seat--4 { transform: translate(-50%, -50%) translateY(150px); }
  .seat--5 { transform: translate(-50%, -50%) translate(-130px, 75px); }
  .seat--6 { transform: translate(-50%, -50%) translate(-130px, -75px); }
  .av { width: 48px; height: 48px; margin: -24px 0 0 -24px; font-size: 19px; }
  .chip--a { left: -6px; }
  .chip--b { right: -4px; }

  /* 其余区块单列 */
  .steps, .features, .topics { grid-template-columns: 1fr; }
  .cognition { grid-template-columns: 1fr; gap: 32px; }
  .sec-title h2 { font-size: 23px; letter-spacing: 3px; }
  .sec-title__line { max-width: 60px; }
  .sec-lede { margin-bottom: 36px; font-size: 15px; }

  .cta__inner { padding: 52px 22px; }
  .cta__title { font-size: 27px; }

  .footer__inner { flex-direction: column; gap: 24px; }
}

@media (max-width: 420px) {
  .hero__title { font-size: 32px; }
  .stage { width: 300px; height: 300px; }
  .seat--1 { transform: translate(-50%, -50%) translateY(-132px); }
  .seat--2 { transform: translate(-50%, -50%) translate(114px, -66px); }
  .seat--3 { transform: translate(-50%, -50%) translate(114px, 66px); }
  .seat--4 { transform: translate(-50%, -50%) translateY(132px); }
  .seat--5 { transform: translate(-50%, -50%) translate(-114px, 66px); }
  .seat--6 { transform: translate(-50%, -50%) translate(-114px, -66px); }
  .chip { max-width: 150px; font-size: 11.5px; }
}