/* ============ 主题变量 ============ */
:root {
  --bg: #05060a;
  --bg-alt: #0a0d16;
  --panel: rgba(255, 255, 255, 0.04);
  --panel-border: rgba(255, 255, 255, 0.09);
  --text: #e8ecf4;
  --text-dim: #9aa3b5;
  --red: #c8332b;       /* 三体星 / 危机红 */
  --red-soft: #ff5a4d;
  --cyan: #3fd0d6;      /* 智子青 */
  --gold: #d8a657;      /* 黑暗金 */
  --maxw: 1140px;
  --radius: 16px;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.45);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }

/* ============ 导航 ============ */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px clamp(18px, 5vw, 48px);
  background: rgba(5, 6, 10, 0.55);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: background 0.3s, border-color 0.3s;
}
.nav.scrolled {
  background: rgba(5, 6, 10, 0.92);
  border-bottom-color: var(--panel-border);
}
.nav__brand { display: flex; align-items: center; gap: 12px; font-weight: 700; }
.nav__logo {
  display: grid; place-items: center;
  width: 34px; height: 34px;
  border-radius: 9px;
  background: linear-gradient(135deg, var(--red), var(--gold));
  color: #fff; font-size: 18px; font-weight: 800;
  box-shadow: 0 0 18px rgba(200, 51, 43, 0.5);
}
.nav__title { font-size: 15px; letter-spacing: 1px; }
.nav__menu { display: flex; gap: 28px; list-style: none; }
.nav__menu a {
  font-size: 14px; color: var(--text-dim);
  position: relative; transition: color 0.25s;
}
.nav__menu a::after {
  content: ""; position: absolute; left: 0; bottom: -6px;
  width: 0; height: 2px; background: var(--red-soft);
  transition: width 0.25s;
}
.nav__menu a:hover { color: var(--text); }
.nav__menu a:hover::after { width: 100%; }
.nav__toggle {
  display: none; flex-direction: column; gap: 5px;
  background: none; border: none; cursor: pointer; padding: 6px;
}
.nav__toggle span {
  width: 24px; height: 2px; background: var(--text);
  border-radius: 2px; transition: transform 0.3s, opacity 0.3s;
}
.nav__toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav__toggle.open span:nth-child(2) { opacity: 0; }
.nav__toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ============ Hero ============ */
.hero {
  position: relative;
  min-height: 100vh;
  display: grid;
  place-items: center;
  text-align: center;
  overflow: hidden;
}
.hero__canvas { position: absolute; inset: 0; width: 100%; height: 100%; }
.hero__overlay {
  position: absolute; inset: 0;
  background:
    radial-gradient(120% 90% at 50% 0%, rgba(200,51,43,0.18), transparent 55%),
    radial-gradient(120% 90% at 50% 100%, rgba(63,208,214,0.10), transparent 55%),
    linear-gradient(180deg, rgba(5,6,10,0.4), rgba(5,6,10,0.85));
}
.hero__content { position: relative; z-index: 2; padding: 0 20px; max-width: 760px; }
.hero__eyebrow {
  color: var(--cyan); letter-spacing: 4px; font-size: 13px;
  text-transform: uppercase; margin-bottom: 18px;
}
.hero__title {
  font-size: clamp(56px, 14vw, 150px);
  font-weight: 900; letter-spacing: 8px; line-height: 1;
  background: linear-gradient(180deg, #fff, #c9d2e0 60%, var(--gold));
  -webkit-background-clip: text; background-clip: text; color: transparent;
  text-shadow: 0 0 60px rgba(200, 51, 43, 0.25);
}
.hero__subtitle {
  margin-top: 22px; font-size: clamp(15px, 2.4vw, 20px);
  color: var(--text-dim); letter-spacing: 1px;
}
.hero__actions { margin-top: 38px; display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }
.hero__scroll {
  position: absolute; bottom: 26px; left: 50%; transform: translateX(-50%);
  width: 26px; height: 42px; border: 2px solid var(--text-dim);
  border-radius: 14px; z-index: 2;
}
.hero__scroll span {
  position: absolute; top: 8px; left: 50%; transform: translateX(-50%);
  width: 4px; height: 8px; border-radius: 2px; background: var(--cyan);
  animation: scrollDot 1.6s infinite;
}
@keyframes scrollDot { 0% { opacity: 0; top: 8px; } 40% { opacity: 1; } 100% { opacity: 0; top: 24px; } }

/* ============ 按钮 ============ */
.btn {
  display: inline-block; padding: 13px 30px; border-radius: 999px;
  font-size: 14px; font-weight: 600; letter-spacing: 1px;
  transition: transform 0.2s, box-shadow 0.2s, background 0.2s;
  cursor: pointer;
}
.btn--primary { background: linear-gradient(135deg, var(--red), var(--red-soft)); color: #fff; box-shadow: 0 10px 30px rgba(200,51,43,0.4); }
.btn--primary:hover { transform: translateY(-3px); box-shadow: 0 14px 36px rgba(200,51,43,0.55); }
.btn--ghost { border: 1px solid var(--panel-border); color: var(--text); background: var(--panel); }
.btn--ghost:hover { border-color: var(--cyan); color: var(--cyan); transform: translateY(-3px); }

/* ============ 通用 section ============ */
.section { padding: clamp(70px, 11vw, 130px) clamp(18px, 5vw, 48px); max-width: var(--maxw); margin: 0 auto; }
.section--alt { max-width: none; background: var(--bg-alt); }
.section--alt > * { max-width: var(--maxw); margin-left: auto; margin-right: auto; }
.section__head { text-align: center; margin-bottom: 56px; }
.section__tag {
  display: inline-block; padding: 5px 14px; border-radius: 999px;
  font-size: 12px; letter-spacing: 3px; color: var(--cyan);
  border: 1px solid rgba(63,208,214,0.35); background: rgba(63,208,214,0.06);
}
.section__title { font-size: clamp(28px, 5vw, 44px); margin: 18px 0 14px; font-weight: 800; letter-spacing: 2px; }
.section__lead { color: var(--text-dim); max-width: 620px; margin: 0 auto; font-size: 15px; }

/* ============ 公理 ============ */
.axioms { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }
.axiom {
  background: var(--panel); border: 1px solid var(--panel-border);
  border-radius: var(--radius); padding: 30px; position: relative; overflow: hidden;
}
.axiom::before {
  content: ""; position: absolute; top: 0; left: 0; width: 100%; height: 3px;
  background: linear-gradient(90deg, var(--red), var(--gold));
}
.axiom__num { font-size: 40px; font-weight: 900; color: rgba(200,51,43,0.25); line-height: 1; }
.axiom h3 { margin: 10px 0 10px; font-size: 19px; }
.axiom p { color: var(--text-dim); font-size: 14px; }

.concepts-row { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; margin-top: 22px; }
.concept-pill {
  background: var(--panel); border: 1px solid var(--panel-border);
  border-radius: 12px; padding: 20px 22px; font-size: 14px; color: var(--text-dim);
}
.concept-pill strong { color: var(--cyan); display: block; margin-bottom: 6px; font-size: 15px; }

.big-quote {
  margin-top: 48px; text-align: center; font-size: clamp(26px, 6vw, 56px);
  font-weight: 800; letter-spacing: 4px; color: #fff;
  text-shadow: 0 0 40px rgba(200,51,43,0.35);
}

/* ============ 语录轮播 ============ */
.quotes { display: flex; align-items: center; justify-content: center; gap: 18px; }
.quotes__nav {
  flex: 0 0 auto; width: 48px; height: 48px; border-radius: 50%;
  border: 1px solid var(--panel-border); background: var(--panel);
  color: var(--text); font-size: 26px; cursor: pointer; transition: 0.2s;
}
.quotes__nav:hover { border-color: var(--cyan); color: var(--cyan); }
.quote-card {
  flex: 1 1 auto; max-width: 720px; min-height: 180px;
  display: flex; flex-direction: column; justify-content: center; align-items: center;
  text-align: center; padding: 40px; background: var(--panel);
  border: 1px solid var(--panel-border); border-radius: var(--radius);
}
.quote-card blockquote { font-size: clamp(20px, 3.6vw, 30px); font-weight: 700; line-height: 1.5; }
.quote-card figcaption { margin-top: 18px; color: var(--gold); letter-spacing: 1px; }
.quotes__dots { display: flex; gap: 10px; justify-content: center; margin-top: 28px; }
.quotes__dots button {
  width: 10px; height: 10px; border-radius: 50%; border: none;
  background: var(--panel-border); cursor: pointer; transition: 0.2s;
}
.quotes__dots button.active { background: var(--red-soft); width: 26px; border-radius: 6px; }

/* ============ 概念卡片 ============ */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.card {
  background: var(--panel); border: 1px solid var(--panel-border);
  border-radius: var(--radius); padding: 30px; transition: transform 0.25s, border-color 0.25s, box-shadow 0.25s;
}
.card:hover { transform: translateY(-6px); border-color: rgba(63,208,214,0.4); box-shadow: var(--shadow); }
.card__icon { font-size: 38px; margin-bottom: 14px; }
.card h3 { font-size: 20px; margin-bottom: 10px; }
.card p { color: var(--text-dim); font-size: 14px; }

/* ============ 时间线 ============ */
.timeline { list-style: none; position: relative; padding-left: 28px; }
.timeline::before {
  content: ""; position: absolute; left: 7px; top: 6px; bottom: 6px; width: 2px;
  background: linear-gradient(180deg, var(--red), var(--cyan));
}
.timeline__item { position: relative; padding: 0 0 38px 22px; }
.timeline__item::before {
  content: ""; position: absolute; left: -28px; top: 6px;
  width: 16px; height: 16px; border-radius: 50%;
  background: var(--bg); border: 3px solid var(--red-soft);
  box-shadow: 0 0 14px rgba(255,90,77,0.6);
}
.timeline__year { color: var(--gold); font-weight: 800; letter-spacing: 2px; }
.timeline__item h3 { margin: 6px 0 8px; font-size: 19px; }
.timeline__item p { color: var(--text-dim); font-size: 14px; max-width: 560px; }

/* ============ 页脚 ============ */
.footer { background: #04050a; border-top: 1px solid var(--panel-border); padding: 60px 20px; text-align: center; }
.footer__brand { font-size: 20px; font-weight: 800; letter-spacing: 2px; }
.footer__note { color: var(--text-dim); font-size: 13px; margin-top: 10px; }
.footer__quote { color: var(--cyan); margin-top: 18px; font-size: 14px; letter-spacing: 1px; }

/* ============ 滚动揭示动画 ============ */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity 0.7s, transform 0.7s; }
.reveal.visible { opacity: 1; transform: none; }

/* ============ 响应式 ============ */
@media (max-width: 860px) {
  .nav__toggle { display: flex; }
  .nav__menu {
    position: absolute; top: 100%; right: 0; left: 0;
    flex-direction: column; gap: 0; padding: 10px 0;
    background: rgba(5,6,10,0.97); border-bottom: 1px solid var(--panel-border);
    transform: translateY(-12px); opacity: 0; pointer-events: none; transition: 0.25s;
  }
  .nav__menu.open { transform: none; opacity: 1; pointer-events: auto; }
  .nav__menu li { padding: 4px 0; }
  .nav__menu a { display: block; padding: 12px clamp(18px,5vw,48px); }
  .nav__menu a::after { display: none; }
  .axioms, .concepts-row, .cards { grid-template-columns: 1fr; }
  .cards { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
  .quotes__nav { width: 40px; height: 40px; font-size: 22px; }
  .quote-card { padding: 28px 18px; min-height: 160px; }
  .hero__actions { flex-direction: column; align-items: center; }
  .btn { width: 100%; max-width: 280px; text-align: center; }
}