:root {
  --ink: #0e1c30;          /* 主文字色（浅色站上做文字） */
  --ink-2: #ffffff;        /* 卡片底（原深底变量复用为浅色） */
  --paper: #f2f6fc;        /* 浅色区块底 */
  --page: #eaf1f9;         /* 页面整体底色 */
  --white: #ffffff;
  --blue: #2967ff;
  --cyan: #0fb5c9;
  --cyan-soft: #0794a8;
  --line-light: rgba(14, 28, 48, 0.12);
  --line-dark: rgba(255, 255, 255, 0.13);  /* 仍用于个别深色小元素 */
  --muted: #5b6b80;
  --container: min(1180px, calc(100vw - 48px));
  --radius: 24px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: "Manrope", "Noto Sans SC", sans-serif;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
body.modal-open { overflow: hidden; }
a { color: inherit; text-decoration: none; }
button, input { font: inherit; }
button { color: inherit; }
img { max-width: 100%; display: block; }
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}
.skip-link {
  position: fixed; left: 16px; top: -60px; z-index: 1000;
  background: var(--cyan); padding: 12px 18px; border-radius: 10px;
  font-weight: 800; transition: top .2s;
}
.skip-link:focus { top: 16px; }

.page-progress { position: fixed; top: 0; left: 0; right: 0; height: 2px; z-index: 1000; }
.page-progress span { display: block; width: 0; height: 100%; background: linear-gradient(90deg, var(--blue), var(--cyan)); }

.site-header {
  width: var(--container); height: 92px; margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  position: absolute; z-index: 20; left: 50%; transform: translateX(-50%);
  color: var(--ink); border-bottom: 1px solid var(--line-light);
}
.brand { display: flex; align-items: center; gap: 13px; }
.brand-mark {
  width: 48px; height: 48px; border-radius: 14px; overflow: hidden; background: white;
  display: grid; place-items: center; box-shadow: 0 8px 30px rgba(31, 123, 255, .16);
}
.brand-mark img { width: 100%; height: 100%; object-fit: cover; }
.brand-copy { display: flex; flex-direction: column; line-height: 1.05; }
.brand-copy strong { font-size: 16px; letter-spacing: -.02em; }
.brand-copy small { margin-top: 5px; font-size: 8px; letter-spacing: .18em; opacity: .5; }
.site-nav { display: flex; align-items: center; gap: 32px; font-size: 13px; font-weight: 600; }
.site-nav > a:not(.nav-cta) { position: relative; opacity: .72; transition: opacity .2s; }
.site-nav > a:not(.nav-cta)::after {
  content: ""; position: absolute; height: 1px; bottom: -8px; left: 0; width: 0;
  background: var(--cyan); transition: width .25s;
}
.site-nav > a:hover { opacity: 1; }
.site-nav > a:hover::after { width: 100%; }
.nav-cta {
  display: flex; align-items: center; gap: 16px; padding: 12px 16px 12px 19px;
  border: 1px solid rgba(41, 103, 255, .35); border-radius: 999px; transition: .25s;
}
button.nav-cta { appearance: none; background: transparent; color: inherit; cursor: pointer; }
.nav-cta:hover { background: var(--blue); color: white; }
.nav-cta span { color: var(--blue); font-size: 16px; }
.nav-cta:hover span { color: white; }
.menu-toggle { display: none; }

.hero {
  position: relative; min-height: 860px; height: auto; max-height: none;
  background: linear-gradient(180deg, #f6f9ff 0%, #eaf3ff 55%, #e4efff 100%);
  color: var(--ink); overflow: hidden;
}
#network-canvas, #join-canvas { position: absolute; inset: 0; width: 100%; height: 100%; }
.hero-grid {
  position: absolute; inset: 0; opacity: .1; pointer-events: none;
  background-image: linear-gradient(rgba(41, 103, 255, .16) 1px, transparent 1px), linear-gradient(90deg, rgba(41, 103, 255, .16) 1px, transparent 1px);
  background-size: 80px 80px;
  mask-image: linear-gradient(to bottom, transparent, black 20%, black 70%, transparent 100%);
}
.hero-glow { position: absolute; border-radius: 50%; filter: blur(80px); opacity: .16; }
.hero-glow-a { width: 520px; height: 520px; right: 4%; top: 16%; background: var(--blue); opacity: .12; }
.hero-glow-b { width: 360px; height: 360px; left: -8%; bottom: -8%; background: var(--cyan); opacity: .1; }
.hero-content {
  width: var(--container); position: relative; z-index: 3;
  margin: 0 auto; padding: 150px 48% 40px 0;
}
/* hero 三站引导卡：窄容器横排自适应换行 */
.hero-guide { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 26px; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 10px; padding: 9px 14px;
  border: 1px solid rgba(41, 103, 255, .22); background: rgba(41, 103, 255, .07);
  border-radius: 999px; color: var(--cyan-soft); font-size: 12px; letter-spacing: .14em;
}
.status-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--cyan); box-shadow: 0 0 0 5px rgba(32, 211, 220, .1); animation: pulse 2s infinite; }
@keyframes pulse { 50% { box-shadow: 0 0 0 9px rgba(32, 211, 220, 0); } }
.hero h1 {
  margin: 28px 0 24px; max-width: 800px; font-family: "Noto Sans SC", sans-serif;
  font-size: clamp(52px, 6.1vw, 92px); font-weight: 900; line-height: 1.05; letter-spacing: -.065em;
  white-space: nowrap;
}
.hero h1 span {
  color: transparent; -webkit-text-stroke: 1.5px rgba(15, 181, 201, .85);
  text-shadow: 0 0 35px rgba(32, 211, 220, .12);
}
.hero-lead { max-width: 650px; font-size: 17px; line-height: 1.9; color: var(--muted); }
.hero-actions { display: flex; gap: 14px; margin-top: 36px; }
.button {
  min-height: 54px; padding: 0 24px; border-radius: 999px; border: 1px solid transparent;
  display: inline-flex; justify-content: center; align-items: center; gap: 24px;
  font-size: 14px; font-weight: 800; cursor: pointer; transition: transform .25s, box-shadow .25s, background .25s;
}
.button:hover { transform: translateY(-3px); }
.button-primary { background: linear-gradient(120deg, var(--blue), #1c8cff 62%, var(--cyan)); color: white; box-shadow: 0 16px 44px rgba(29, 104, 255, .3); }
.button-primary:hover { box-shadow: 0 20px 54px rgba(29, 104, 255, .46); }
.button-ghost { color: var(--ink); border-color: rgba(14, 28, 48, .22); background: rgba(255,255,255,.65); }
.button-ghost:hover { background: white; }
.button-icon { font-size: 18px; }
.hero-proof { display: flex; gap: 42px; margin-top: 48px; }
.hero-proof div { display: grid; grid-template-columns: auto auto; align-items: baseline; gap: 8px; }
.hero-proof strong { font-size: 26px; letter-spacing: -.06em; }
.hero-proof span { color: var(--muted); font-size: 11px; letter-spacing: .06em; }

.hero-orbit { position: absolute; z-index: 4; width: 480px; height: 480px; right: max(4vw, calc((100vw - 1180px)/2)); top: 50%; transform: translateY(-45%); }
.orbit-shell { width: 100%; height: 100%; position: relative; display: grid; place-items: center; perspective: 800px; }
.orbit-shell::before { content: ""; position: absolute; width: 78%; height: 78%; border-radius: 50%; background: radial-gradient(circle, rgba(41, 103, 255, .16), transparent 66%); filter: blur(5px); }
.orbit-ring { position: absolute; border: 1px solid rgba(15, 181, 201, .35); border-radius: 50%; }
.orbit-ring-one { width: 82%; height: 82%; animation: spin 18s linear infinite; }
.orbit-ring-one::after, .orbit-ring-two::after { content: ""; position: absolute; width: 7px; height: 7px; border-radius: 50%; background: var(--cyan); box-shadow: 0 0 18px var(--cyan); top: -4px; left: 50%; }
.orbit-ring-two { width: 61%; height: 61%; border-style: dashed; animation: spinReverse 13s linear infinite; }
.orbit-ring-two::after { background: var(--blue); box-shadow: 0 0 18px var(--blue); top: auto; bottom: -4px; }
.orbit-core {
  position: relative; width: 220px; height: 220px; border-radius: 50%; overflow: hidden;
  padding: 22px; background: rgba(255,255,255,.98); box-shadow: 0 0 0 1px rgba(255,255,255,.2), 0 30px 100px rgba(14, 91, 255, .35);
  animation: float 5s ease-in-out infinite;
}
.orbit-core img { width: 100%; height: 100%; object-fit: cover; border-radius: 50%; }
.orbit-node {
  position: absolute; display: grid; place-items: center; width: 58px; height: 58px;
  border: 1px solid rgba(41, 103, 255, .25); border-radius: 50%; background: rgba(255, 255, 255, .9);
  backdrop-filter: blur(10px); font-size: 9px; font-weight: 800; color: var(--cyan-soft); letter-spacing: .08em;
}
.node-one { top: 9%; left: 19%; }
.node-two { right: 5%; top: 43%; }
.node-three { left: 12%; bottom: 8%; width: 68px; height: 68px; }
.signal-card {
  position: absolute; display: flex; gap: 12px; align-items: center; padding: 12px 15px;
  border: 1px solid var(--line-light); background: rgba(255, 255, 255, .82); backdrop-filter: blur(14px);
  border-radius: 13px; box-shadow: 0 15px 50px rgba(24, 60, 120, .12);
}
.signal-card-a { left: -20px; top: 42%; }
.signal-card-b { right: -12px; bottom: 15%; }
.signal-card small { display: block; font-size: 8px; color: var(--muted); letter-spacing: .12em; }
.signal-card strong { display: block; margin-top: 3px; font-size: 10px; letter-spacing: .12em; }
.signal-icon { font-size: 26px; color: var(--cyan); }
.live-wave { position: relative; width: 25px; height: 25px; border: 1px solid rgba(32,211,220,.35); border-radius: 50%; }
.live-wave::before { content: ""; position: absolute; inset: 7px; background: var(--cyan); border-radius: 50%; animation: pulse 1.5s infinite; }
@keyframes spin { to { transform: rotate(360deg); } }
@keyframes spinReverse { to { transform: rotate(-360deg); } }
@keyframes float { 50% { transform: translateY(-12px) rotate(1deg); } }
.scroll-cue {
  position: absolute; z-index: 5; left: 50%; transform: translateX(-50%); bottom: 26px;
  display: flex; flex-direction: column; align-items: center; gap: 9px; font-size: 8px; letter-spacing: .2em; color: rgba(14, 28, 48, .45);
}
.scroll-cue i { width: 1px; height: 38px; background: linear-gradient(var(--cyan), transparent); animation: scrollLine 1.8s ease-in-out infinite; transform-origin: top; }
@keyframes scrollLine { 50% { transform: scaleY(.4); opacity: .5; } }

.section { position: relative; padding: 130px 0; }
.section-inner { width: var(--container); margin: 0 auto; }
.section-light { background: var(--paper); }
.section-dark { background: linear-gradient(180deg, #eef4fd, #e7effb); color: var(--ink); }
.section-heading .section-index, .section-index {
  display: block; margin-bottom: 22px; color: var(--blue); font-size: 10px; font-weight: 800; letter-spacing: .24em;
}
.section-dark .section-index, .join-section .section-index { color: #9ff0f8; }
.section-heading h2, .join-section h2 {
  margin: 0; font-family: "Noto Sans SC", sans-serif; font-size: clamp(42px, 5vw, 70px);
  line-height: 1.12; letter-spacing: -.06em; font-weight: 800;
}
.section-heading h2 em, .join-section h2 em { font-style: normal; color: var(--blue); }
.section-dark .section-heading h2 em, .join-section h2 em { color: #9ff0f8; }
.about-grid { display: grid; grid-template-columns: .9fr 1.1fr; column-gap: 100px; }
.about-copy { align-self: end; padding-bottom: 8px; }
.about-copy p { margin: 0; color: var(--muted); font-size: 15px; line-height: 1.9; }
.about-copy .lead-copy { margin-bottom: 24px; color: var(--ink); font-size: 20px; line-height: 1.65; letter-spacing: -.025em; }
.about-copy strong { box-shadow: inset 0 -.42em 0 rgba(32, 211, 220, .22); }
.principles { grid-column: 1/-1; display: grid; grid-template-columns: repeat(3, 1fr); margin-top: 80px; border: 1px solid var(--line-light); border-radius: var(--radius); overflow: hidden; }
.principle-card { min-height: 312px; padding: 30px; position: relative; background: rgba(255,255,255,.55); border-right: 1px solid var(--line-light); transition: transform .3s, background .3s; }
.principle-card:last-child { border-right: 0; }
.principle-card.featured { background: linear-gradient(150deg, #123a8c, #2967ff 75%, #1fa9c9); color: white; }
.principle-card:hover { transform: translateY(-5px); z-index: 2; }
.card-number { font-size: 9px; letter-spacing: .18em; color: var(--muted); }
.mini-icon { width: 48px; height: 48px; border: 1px solid var(--line-light); border-radius: 50%; display: grid; place-items: center; font-size: 21px; margin: 52px 0 30px; color: var(--blue); }
.featured .mini-icon { border-color: var(--line-dark); color: var(--cyan); }
.principle-card h3 { margin: 0 0 12px; font-size: 21px; letter-spacing: -.04em; }
.principle-card p { margin: 0; max-width: 280px; color: var(--muted); font-size: 13px; line-height: 1.75; }
.featured p { color: rgba(255,255,255,.52); }

.section-heading.split { display: flex; justify-content: space-between; align-items: flex-end; }
.section-heading.split > p { max-width: 460px; margin: 0 0 10px; color: var(--muted); font-size: 14px; line-height: 1.9; }
.activity-stack { margin-top: 82px; display: grid; gap: 26px; }
.activity-card {
  position: relative; display: grid; grid-template-columns: 1.05fr .95fr; min-height: 610px;
  border: 1px solid var(--line-light); border-radius: 28px; overflow: hidden; background: var(--white);
  transform-style: preserve-3d; transition: border-color .3s, box-shadow .3s;
  box-shadow: 0 24px 70px rgba(24, 60, 120, .08);
}
.activity-card:hover { border-color: rgba(15, 181, 201, .45); }
.activity-content { padding: clamp(40px, 6vw, 72px); align-self: center; }
.activity-meta { display: flex; align-items: center; gap: 10px; font-size: 9px; letter-spacing: .16em; color: var(--cyan-soft); }
.activity-meta i { width: 24px; height: 1px; background: var(--cyan); opacity: .5; }
.activity-content h3 { margin: 30px 0 24px; font-family: "Noto Sans SC", sans-serif; font-size: clamp(34px, 4vw, 55px); line-height: 1.14; letter-spacing: -.055em; }
.activity-content > p { max-width: 530px; margin: 0; color: var(--muted); font-size: 14px; line-height: 1.9; }
.activity-content ul { list-style: none; margin: 30px 0 0; padding: 0; }
.activity-content li { position: relative; padding: 10px 0 10px 25px; border-bottom: 1px solid var(--line-light); color: rgba(14, 28, 48, .78); font-size: 12px; }
.activity-content li::before { content: "→"; position: absolute; left: 0; color: var(--cyan); }
.activity-visual { position: relative; min-height: 100%; overflow: hidden; }
.tool-visual { background: linear-gradient(145deg, #dcecff, #c7ddff 68%); display: grid; place-items: center; }
.tool-visual::before { content: ""; position: absolute; width: 340px; height: 340px; border-radius: 50%; background: var(--blue); filter: blur(90px); opacity: .16; }
.terminal-window { width: 76%; max-width: 430px; position: relative; z-index: 2; border: 1px solid rgba(255,255,255,.5); border-radius: 17px; background: rgba(10, 22, 40, .92); backdrop-filter: blur(16px); box-shadow: 0 35px 80px rgba(10, 40, 90, .3); transform: rotate(2deg); }
.terminal-bar { height: 44px; display: flex; align-items: center; gap: 7px; padding: 0 14px; border-bottom: 1px solid rgba(255,255,255,.1); }
.terminal-bar i { width: 7px; height: 7px; border-radius: 50%; background: rgba(255,255,255,.2); }
.terminal-bar i:first-child { background: #ff6f70; }
.terminal-bar i:nth-child(2) { background: #ffc756; }
.terminal-bar i:nth-child(3) { background: var(--cyan); }
.terminal-bar span { margin-left: 8px; color: rgba(255,255,255,.28); font-size: 8px; letter-spacing: .14em; }
.terminal-code { padding: 30px 20px 36px; }
.terminal-code p { display: grid; grid-template-columns: 28px 1fr; margin: 0; padding: 14px 0; border-bottom: 1px dashed rgba(255,255,255,.08); }
.terminal-code span { color: rgba(255,255,255,.22); font: 10px monospace; }
.terminal-code code { color: rgba(207, 232, 255, .72); font: 11px/1.5 monospace; }
.terminal-code b { color: var(--cyan); font-weight: normal; }
.terminal-cursor { margin-top: 22px; width: 8px; height: 15px; background: var(--cyan); animation: blink 1s steps(2) infinite; }
@keyframes blink { 50% { opacity: 0; } }
.floating-chip { position: absolute; z-index: 3; padding: 8px 12px; border: 1px solid rgba(41,103,255,.22); background: rgba(255,255,255,.88); backdrop-filter: blur(8px); border-radius: 999px; font-size: 8px; letter-spacing: .12em; color: var(--cyan-soft); }
.chip-a { left: 9%; top: 21%; animation: float 4s ease-in-out infinite; }
.chip-b { right: 8%; bottom: 20%; animation: float 5s 1s ease-in-out infinite; }
.chip-c { left: 16%; bottom: 12%; animation: float 4.5s .5s ease-in-out infinite; }
.mc-card { grid-template-columns: .95fr 1.05fr; }
.voxel-visual { background: linear-gradient(160deg, #d8ecff, #b9d7ff); perspective: 700px; }
.voxel-world { position: absolute; width: 420px; height: 420px; left: 50%; top: 51%; transform: translate(-50%, -50%) rotateX(58deg) rotateZ(-43deg); transform-style: preserve-3d; }
.voxel { position: absolute; width: 42px; height: 42px; background: #7fb3f2; border: 1px solid rgba(255,255,255,.5); box-shadow: inset -9px -9px 0 rgba(20, 70, 140, .18); transform-style: preserve-3d; transition: transform .4s, background .4s; }
.voxel::before, .voxel::after { content: ""; position: absolute; background: inherit; border: inherit; }
.voxel::before { width: 100%; height: 15px; left: -1px; bottom: -16px; transform-origin: top; transform: rotateX(-90deg); filter: brightness(.6); }
.voxel::after { width: 15px; height: 100%; right: -16px; top: -1px; transform-origin: left; transform: rotateY(90deg); filter: brightness(.78); }
.voxel.agent-path { background: #16c8de; box-shadow: 0 0 18px rgba(15,181,201,.4); transform: translateZ(9px); }
.agent-marker { position: absolute; left: 54%; top: 37%; padding: 10px 12px 9px 32px; background: rgba(255,255,255,.92); border: 1px solid rgba(15,181,201,.4); border-radius: 8px; backdrop-filter: blur(8px); box-shadow: 0 10px 30px rgba(10,40,90,.15); }
.agent-marker span { position: absolute; left: 12px; top: 15px; width: 9px; height: 9px; background: var(--cyan); border-radius: 50%; box-shadow: 0 0 15px var(--cyan); }
.agent-marker b, .agent-marker small { display: block; letter-spacing: .11em; color: var(--ink); }
.agent-marker b { font-size: 8px; }
.agent-marker small { margin-top: 3px; color: var(--cyan-soft); font-size: 6px; }
.scan-line { position: absolute; left: 0; right: 0; height: 1px; top: 0; background: linear-gradient(90deg, transparent, var(--cyan), transparent); box-shadow: 0 0 20px var(--cyan); animation: scan 5s linear infinite; opacity: .5; }
@keyframes scan { to { top: 100%; } }
.text-button { display: inline-flex; align-items: center; gap: 18px; margin-top: 28px; padding: 0; border: 0; background: none; color: var(--cyan-soft); font-size: 11px; font-weight: 700; cursor: pointer; }
.text-button i { width: 24px; height: 24px; display: grid; place-items: center; border: 1px solid rgba(15,181,201,.4); border-radius: 50%; font-style: normal; transition: transform .25s; }
.text-button[aria-expanded="true"] i { transform: rotate(45deg); }
.activity-detail { display: grid; grid-template-rows: 0fr; transition: grid-template-rows .35s; }
.activity-detail p { overflow: hidden; margin: 0; color: var(--muted); font-size: 12px; line-height: 1.8; }
.activity-detail.open { grid-template-rows: 1fr; }
.activity-detail.open p { margin-top: 20px; }

.section-schedule { background: var(--white); }
.roadmap { position: relative; display: grid; grid-template-columns: repeat(3,1fr); margin-top: 86px; border-top: 1px solid var(--line-light); }
.roadmap::before { content: ""; position: absolute; top: -1px; left: 0; height: 2px; width: 33.333%; background: var(--blue); transition: transform .4s ease; transform: translateX(calc(var(--active-step, 0) * 100%)); }
.roadmap-step { position: relative; padding: 42px 46px 44px 0; border-right: 1px solid var(--line-light); outline: none; cursor: pointer; }
.roadmap-step:nth-child(2) { padding-left: 46px; }
.roadmap-step:nth-child(3) { padding-left: 46px; border-right: 0; }
.step-id { color: var(--muted); font-size: 8px; letter-spacing: .18em; }
.step-dot { position: absolute; width: 11px; height: 11px; top: -6px; left: 0; background: white; border: 2px solid #aeb8c6; border-radius: 50%; transition: .3s; }
.roadmap-step:nth-child(n+2) .step-dot { left: 46px; }
.roadmap-step.active .step-dot { border-color: var(--blue); background: var(--blue); box-shadow: 0 0 0 6px rgba(41,103,255,.1); }
.roadmap-step small { display: block; margin-top: 38px; color: var(--blue); font-size: 10px; font-weight: 700; }
.roadmap-step h3 { margin: 12px 0 12px; font-size: 25px; letter-spacing: -.04em; }
.roadmap-step p { max-width: 290px; margin: 0; color: var(--muted); font-size: 13px; line-height: 1.7; }
.schedule-note { display: grid; grid-template-columns: auto 1fr; gap: 20px; align-items: center; margin-top: 35px; padding: 24px 28px; background: var(--paper); border-radius: 18px; }
.schedule-icon { width: 44px; height: 44px; display: grid; place-items: center; border-radius: 50%; background: white; color: var(--blue); font-size: 22px; }
.schedule-note span { font-size: 10px; color: var(--blue); font-weight: 800; letter-spacing: .08em; }
.schedule-note p { margin: 5px 0 0; color: var(--muted); font-size: 12px; line-height: 1.65; }

.join-section { min-height: 910px; display: grid; place-items: center; overflow: hidden; background: linear-gradient(160deg, #0b2a66, #2967ff 70%, #17a9c4); color: white; text-align: center; }
.join-section::before { content: ""; position: absolute; inset: 0; background: radial-gradient(circle at center, rgba(255, 255, 255, .12), transparent 48%); }
.join-orb { position: absolute; width: 540px; height: 540px; border-radius: 50%; border: 1px solid rgba(255,255,255,.18); }
.join-orb::before, .join-orb::after { content: ""; position: absolute; border: 1px solid rgba(255,255,255,.12); border-radius: 50%; inset: 12%; }
.join-orb::after { inset: 26%; border-style: dashed; animation: spin 24s linear infinite; }
.join-inner { position: relative; z-index: 2; display: flex; flex-direction: column; align-items: center; }
.join-section h2 { font-size: clamp(48px, 6vw, 82px); }
.join-section p { margin: 30px 0 34px; color: rgba(255,255,255,.56); font-size: 15px; line-height: 1.9; }
.join-button { min-width: 280px; }
.contact-grid { width: min(880px, 100%); display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 30px; text-align: left; }
.contact-card {
  position: relative; min-width: 0; min-height: 116px; padding: 20px; border: 1px solid rgba(255,255,255,.11);
  border-radius: 18px; background: rgba(255,255,255,.035); color: white; cursor: pointer;
  transition: transform .25s, border-color .25s, background .25s;
}
button.contact-card { width: 100%; appearance: none; font: inherit; text-align: left; }
.contact-card:hover { transform: translateY(-4px); border-color: rgba(32,211,220,.38); background: rgba(32,211,220,.055); }
.contact-card small { display: block; color: #9ff0f8; font-size: 8px; font-weight: 800; letter-spacing: .17em; }
.contact-card strong { display: block; margin: 15px 0 8px; overflow: hidden; text-overflow: ellipsis; font-size: 12px; letter-spacing: -.01em; white-space: nowrap; }
.contact-card > span { color: rgba(255,255,255,.36); font-size: 9px; }
.join-tags { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; margin-top: 44px; }
.join-tags span { padding: 8px 12px; border: 1px solid rgba(255,255,255,.1); border-radius: 999px; color: rgba(255,255,255,.38); font-size: 9px; letter-spacing: .05em; }

.site-footer { min-height: 230px; padding: 54px max(24px, calc((100vw - 1180px)/2)); background: #f7fafd; color: var(--ink); display: flex; align-items: flex-end; justify-content: space-between; border-top: 1px solid var(--line-light); }
.footer-brand { display: flex; align-items: flex-end; gap: 22px; }
.footer-brand img { width: 68px; height: 68px; object-fit: cover; border-radius: 15px; }
.footer-brand p { margin: 0 0 2px; color: var(--muted); font-size: 9px; line-height: 1.7; letter-spacing: .16em; }
.footer-meta { display: flex; gap: 32px; color: var(--muted); font-size: 9px; letter-spacing: .15em; }
.footer-meta a { color: var(--cyan-soft); }

.join-modal { position: fixed; inset: 0; width: min(540px, calc(100vw - 32px)); max-height: calc(100dvh - 32px); margin: auto; border: 1px solid var(--line-light); border-radius: 26px; padding: 46px; background: #ffffff; color: var(--ink); box-shadow: 0 30px 100px rgba(10, 40, 90, .35); }
.join-modal::backdrop { background: rgba(7, 17, 31, .45); backdrop-filter: blur(10px); }
.modal-close { position: absolute; right: 18px; top: 16px; width: 38px; height: 38px; border-radius: 50%; border: 1px solid var(--line-light); background: transparent; color: var(--ink); font-size: 24px; cursor: pointer; }
.modal-label { color: var(--cyan-soft); font-size: 9px; font-weight: 800; letter-spacing: .18em; }
.join-modal h2 { margin: 17px 0 14px; font-size: 35px; letter-spacing: -.05em; }
.join-modal > p { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.8; }
.modal-steps { display: grid; margin: 28px 0; border-top: 1px solid var(--line-light); }
.modal-steps > a, .modal-steps > button { display: grid; grid-template-columns: 24px 1fr auto; align-items: center; gap: 10px; width: 100%; padding: 15px 0; border: 0; border-bottom: 1px solid var(--line-light); background: none; color: rgba(14, 28, 48, .78); text-align: left; font-size: 12px; cursor: pointer; }
.modal-steps b { color: var(--cyan-soft); font-size: 9px; }
.modal-steps i { color: var(--cyan-soft); font-style: normal; }

.reveal { opacity: 0; transform: translateY(24px); transition: opacity .8s ease, transform .8s ease; }
.reveal.visible { opacity: 1; transform: translateY(0); }

@media (max-width: 1050px) {
  .hero-content { padding-right: 41%; }
  .hero-orbit { width: 390px; height: 390px; right: -30px; }
  .orbit-core { width: 180px; height: 180px; }
  .activity-card, .mc-card { grid-template-columns: 1fr 1fr; }
  .activity-content { padding: 46px; }
}

@media (max-width: 820px) {
  :root { --container: min(100% - 32px, 680px); }
  .site-header { height: 76px; }
  .brand-mark { width: 40px; height: 40px; border-radius: 11px; }
  .brand-copy small { display: none; }
  .menu-toggle { display: grid; gap: 6px; width: 42px; height: 42px; place-content: center; border: 1px solid rgba(14,28,48,.2); border-radius: 50%; background: rgba(255,255,255,.7); }
  .menu-toggle span:not(.sr-only) { width: 17px; height: 1px; background: var(--ink); transition: .25s; }
  .menu-toggle[aria-expanded="true"] span:first-child { transform: translateY(3.5px) rotate(45deg); }
  .menu-toggle[aria-expanded="true"] span:nth-child(2) { transform: translateY(-3.5px) rotate(-45deg); }
  .site-nav { position: fixed; display: flex; flex-direction: column; align-items: stretch; gap: 0; left: 16px; right: 16px; top: 84px; padding: 14px; background: rgba(255,255,255,.97); border: 1px solid var(--line-light); border-radius: 18px; backdrop-filter: blur(18px); opacity: 0; visibility: hidden; transform: translateY(-10px); transition: .25s; }
  .site-nav.open { opacity: 1; visibility: visible; transform: translateY(0); }
  .site-nav > a { padding: 15px; }
  .nav-cta { margin-top: 4px; justify-content: space-between; }
  .hero { min-height: 940px; height: auto; }
  .hero-content { position: relative; top: 0; left: 0; transform: none; padding: 130px 0 420px; width: var(--container); margin: 0 auto; }
  .hero h1 { font-size: clamp(40px, 10vw, 72px); }
  .hero-orbit { width: 360px; height: 360px; right: 50%; top: auto; bottom: 36px; transform: translateX(50%); }
  .signal-card-a { left: 5px; }
  .signal-card-b { right: 5px; }
  .scroll-cue { display: none; }
  .about-grid { grid-template-columns: 1fr; gap: 44px; }
  .principles { grid-template-columns: 1fr; margin-top: 20px; }
  .principle-card { min-height: 250px; border-right: 0; border-bottom: 1px solid var(--line-light); }
  .principle-card:last-child { border-bottom: 0; }
  .mini-icon { margin: 35px 0 24px; }
  .section-heading.split { align-items: flex-start; flex-direction: column; gap: 32px; }
  .activity-card, .mc-card { grid-template-columns: 1fr; }
  .activity-visual { min-height: 440px; }
  .mc-card .activity-content { order: 2; }
  .mc-card .activity-visual { order: 1; }
  .roadmap { grid-template-columns: 1fr; border-top: 0; border-left: 1px solid var(--line-light); margin-left: 8px; }
  .roadmap::before { left: -1px; top: 0; width: 2px; height: 33.333%; transform: translateY(calc(var(--active-step, 0) * 100%)); }
  .roadmap-step, .roadmap-step:nth-child(2), .roadmap-step:nth-child(3) { padding: 10px 18px 42px 42px; border-right: 0; }
  .step-dot, .roadmap-step:nth-child(n+2) .step-dot { top: 4px; left: -6px; }
  .roadmap-step small { margin-top: 24px; }
  .contact-grid { grid-template-columns: 1fr; max-width: 520px; }
  .site-footer { align-items: flex-start; gap: 46px; flex-direction: column; }
  .footer-meta { width: 100%; justify-content: space-between; gap: 10px; }
}

@media (max-width: 520px) {
  .section { padding: 92px 0; }
  .hero-content { padding-top: 132px; }
  .eyebrow { font-size: 10px; letter-spacing: .09em; }
  .hero h1 { letter-spacing: -.075em; }
  .desktop-only { display: none; }
  .hero-lead { font-size: 14px; }
  .hero-actions { flex-direction: column; }
  .hero-actions .button { width: 100%; }
  .hero-proof { justify-content: space-between; gap: 10px; }
  .hero-proof div { grid-template-columns: 1fr; gap: 3px; }
  .hero-proof strong { font-size: 23px; }
  .hero-orbit { width: 330px; height: 330px; }
  .orbit-core { width: 155px; height: 155px; }
  .orbit-node { width: 48px; height: 48px; }
  .node-three { width: 58px; height: 58px; }
  .signal-card-a { top: 48%; }
  .section-heading h2, .join-section h2 { font-size: 41px; }
  .about-copy .lead-copy { font-size: 18px; }
  .activity-content { padding: 34px 28px 40px; }
  .activity-visual { min-height: 360px; }
  .terminal-window { width: 88%; }
  .voxel-world { transform: translate(-50%, -50%) scale(.82) rotateX(58deg) rotateZ(-43deg); }
  .join-modal { padding: 42px 24px 30px; }
  .join-modal h2 { font-size: 29px; }
  .contact-grid { grid-template-columns: 1fr; }
  .contact-card { min-height: 96px; }
  .join-section { padding-top: 100px; padding-bottom: 100px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
  .reveal { opacity: 1; transform: none; }
}

/* ============================================================
   追加规则：社团平台导航入口 + 主站介绍双卡区
   （只新增，不改动上方任何既有规则）
   ============================================================ */

/* 导航「社团平台」高亮胶囊：蓝→青渐变底白字，hover 上浮并增强投影 */
.nav-platform,
.site-nav > a.nav-platform {
  display: inline-flex; align-items: center; gap: 10px; padding: 11px 20px;
  border-radius: 999px; background: linear-gradient(120deg, var(--blue), #1c8cff 62%, var(--cyan));
  color: white; font-size: 13px; font-weight: 800; letter-spacing: .02em;
  box-shadow: 0 10px 26px rgba(29, 104, 255, .26); opacity: 1;
  transition: transform .25s, box-shadow .25s, filter .25s;
}
/* 覆盖 .site-nav > a:not(.nav-cta) 的下划线动效与弱化透明度 */
.site-nav > a.nav-platform::after { content: none; }
.nav-platform:hover,
.site-nav > a.nav-platform:hover {
  opacity: 1; transform: translateY(-2px);
  box-shadow: 0 16px 40px rgba(29, 104, 255, .42); filter: brightness(1.05);
}

/* 主站介绍区：双卡网格 */
.platform-duo {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; margin-top: 60px;
}
.platform-card {
  background: var(--white); border: 1px solid var(--line-light); border-radius: var(--radius);
  padding: 34px 30px; box-shadow: 0 24px 70px rgba(24, 60, 120, .08);
  transition: transform .3s, box-shadow .3s, border-color .3s;
}
.platform-card:hover {
  transform: translateY(-5px); border-color: rgba(41, 103, 255, .38);
  box-shadow: 0 34px 92px rgba(24, 60, 120, .16);
}
/* 卡片头小徽章：沿用 .section-index 的蓝色小字宽字距风格 */
.platform-card-head {
  display: inline-flex; align-items: center; gap: 10px;
  color: var(--blue); font-size: 10px; font-weight: 800; letter-spacing: .24em;
}
.platform-card-head::before { content: ""; width: 22px; height: 1px; background: var(--cyan); opacity: .65; }
.platform-card h3 {
  margin: 16px 0 12px; font-family: "Noto Sans SC", sans-serif;
  font-size: 24px; font-weight: 800; letter-spacing: -.04em; line-height: 1.3;
}
.platform-card p { margin: 0; color: var(--muted); font-size: 14px; line-height: 1.8; }
.platform-card .button { margin-top: 28px; }

@media (max-width: 820px) {
  .site-nav > a.nav-platform { justify-content: center; padding: 14px 20px; margin-top: 6px; }
  .platform-duo { grid-template-columns: 1fr; margin-top: 44px; }
  .platform-card { padding: 28px 24px; }
}