/* xDAN AI — official site · v2「宣言 + 心智 / 秩序 / 手艺」
   深色实验室风格；品牌色取自 logo（紫 → 天蓝 / 粉 → 橙）。 */

:root {
  --bg: #06071a;
  --bg-2: #0a0c22;
  --panel: rgba(255, 255, 255, 0.035);
  --line: rgba(255, 255, 255, 0.09);
  --line-2: rgba(255, 255, 255, 0.16);
  --text: #eceefb;
  --muted: #9aa0c3;
  --dim: #646b92;
  --indigo: #4a54ff;
  --sky: #38bdf8;
  --violet: #8b5cf6;
  --ok: #34d399;
  --err: #fb7185;
  --grad: linear-gradient(100deg, #a78bfa 0%, #60a5fa 30%, #c084fc 58%, #f472b6 80%, #fb923c 100%);
  --grad-cool: linear-gradient(90deg, #8b5cf6, #4a54ff 55%, #38bdf8);
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "PingFang SC", "HarmonyOS Sans SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", "Segoe UI", sans-serif;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --wrap: 1200px;
  --gutter: 24px;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font-family: var(--sans); font-size: 16px; line-height: 1.7; -webkit-font-smoothing: antialiased; overflow-x: hidden; }
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }
b, strong { font-weight: 650; color: #fff; }
button, input, select, textarea { font: inherit; color: inherit; }
::selection { background: rgba(74, 84, 255, .55); color: #fff; }
:focus-visible { outline: 2px solid var(--sky); outline-offset: 3px; border-radius: 6px; }

.wrap { width: 100%; max-width: var(--wrap); margin: 0 auto; padding: 0 var(--gutter); }
.muted { color: var(--muted); }
.skip { position: absolute; left: -999px; top: 8px; z-index: 100; background: #fff; color: #000; padding: 8px 12px; border-radius: 8px; }
.skip:focus { left: 8px; }
em { font-style: normal; background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.foot { font-size: 12px; color: var(--dim); margin: 16px 0 0; line-height: 1.6; }
.kicker { font-family: var(--mono); font-size: 12px; letter-spacing: .28em; text-transform: uppercase; color: var(--muted); margin: 0 0 28px; display: flex; align-items: center; gap: 14px; }
.kicker::before { content: ""; width: 28px; height: 1px; background: var(--line-2); }

/* ---------- buttons ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; height: 48px; padding: 0 24px; border-radius: 999px; font-weight: 650; font-size: 15px; border: 1px solid transparent; cursor: pointer; white-space: nowrap; transition: transform .2s, box-shadow .2s; }
.btn--sm { height: 38px; padding: 0 18px; font-size: 14px; }
.btn--block { width: 100%; }
.btn--primary { background: linear-gradient(100deg, #5b4bff, #3f7bff 60%, #38bdf8); color: #fff; box-shadow: 0 8px 30px -10px rgba(74, 84, 255, .8); }
.btn--primary:hover { transform: translateY(-1px); box-shadow: 0 12px 40px -10px rgba(74, 84, 255, .95); }
.btn[disabled] { opacity: .6; cursor: progress; transform: none; }

/* ---------- nav ---------- */
.nav { position: fixed; inset: 0 0 auto 0; z-index: 50; border-bottom: 1px solid transparent; transition: background .3s, border-color .3s; }
.nav.is-scrolled { background: rgba(6, 7, 26, .72); backdrop-filter: saturate(160%) blur(16px); -webkit-backdrop-filter: saturate(160%) blur(16px); border-color: var(--line); }
.nav__inner { display: flex; align-items: center; gap: 24px; height: 68px; }
.brand { display: flex; align-items: center; gap: 10px; flex: 0 0 auto; }
.brand__text { display: flex; flex-direction: column; line-height: 1.05; }
.brand__text b { font-size: 15px; letter-spacing: .04em; }
.brand__text i { font-style: normal; font-size: 11px; color: var(--muted); letter-spacing: .12em; font-weight: 600; }
.nav__links { display: flex; gap: 4px; margin-left: auto; }
.nav__links a { padding: 8px 14px; border-radius: 8px; font-size: 14px; color: var(--muted); letter-spacing: .04em; transition: color .2s, background .2s; }
.nav__links a:hover, .nav__links a.is-active { color: #fff; background: rgba(255,255,255,.05); }
.nav__right { display: flex; align-items: center; gap: 12px; }
.lang { display: inline-flex; padding: 3px; border: 1px solid var(--line-2); border-radius: 999px; }
.lang button { border: 0; background: transparent; height: 28px; min-width: 36px; padding: 0 8px; border-radius: 999px; font-size: 12px; font-weight: 700; color: var(--muted); cursor: pointer; }
html[data-lang="zh"] .lang [data-set-lang="zh"], html[data-lang="en"] .lang [data-set-lang="en"] { background: #fff; color: var(--bg); }
.nav__burger { display: none; width: 40px; height: 40px; border: 1px solid var(--line-2); border-radius: 10px; background: transparent; cursor: pointer; position: relative; }
.nav__burger span { position: absolute; left: 11px; right: 11px; height: 2px; background: #fff; border-radius: 2px; transition: transform .25s, top .25s; }
.nav__burger span:first-child { top: 15px; }
.nav__burger span:last-child { top: 23px; }
.nav.is-open .nav__burger span:first-child { top: 19px; transform: rotate(45deg); }
.nav.is-open .nav__burger span:last-child { top: 19px; transform: rotate(-45deg); }

/* ---------- hero ---------- */
.hero { position: relative; min-height: 100vh; min-height: 100svh; display: flex; align-items: center; overflow: hidden; isolation: isolate; }
.hero__field { position: absolute; inset: 0; width: 100%; height: 100%; z-index: -2; }
.hero__veil { position: absolute; inset: 0; z-index: -1; background: radial-gradient(55% 55% at 25% 50%, rgba(6, 7, 26, .82), transparent 75%), linear-gradient(180deg, transparent 70%, var(--bg)); pointer-events: none; }
.hero__inner { padding-top: 68px; }
.eyebrow { font-family: var(--mono); font-size: 12px; letter-spacing: .3em; color: var(--muted); margin: 0 0 32px; }
.hero__title { font-size: clamp(44px, 8.4vw, 116px); line-height: 1.04; letter-spacing: -0.04em; font-weight: 850; margin: 0 0 32px; }
.hero__sub { font-size: clamp(16px, 1.7vw, 20px); color: #b9bee0; max-width: 640px; margin: 0; line-height: 1.8; }
.hero__cue { position: absolute; left: 50%; bottom: 32px; transform: translateX(-50%); display: flex; flex-direction: column; align-items: center; gap: 10px; font-family: var(--mono); font-size: 11px; letter-spacing: .3em; color: var(--dim); }
.hero__cue i { width: 1px; height: 44px; background: linear-gradient(var(--muted), transparent); animation: cue 2.4s ease-in-out infinite; transform-origin: top; }
@keyframes cue { 0% { transform: scaleY(0); } 50% { transform: scaleY(1); } 100% { transform: scaleY(1); opacity: 0; } }

/* ---------- manifesto ---------- */
.manifesto { padding: 160px 0 40px; }
.mf { list-style: none; margin: 0; padding: 0; display: grid; gap: 28px; }
.mf li { font-size: clamp(28px, 4.6vw, 60px); line-height: 1.2; font-weight: 750; letter-spacing: -0.025em; color: var(--dim); }
.mf li b { color: var(--text); font-weight: 800; }

/* ---------- pillars ---------- */
.pillar { padding: 120px 0; position: relative; }
.pillar + .pillar { border-top: 1px solid var(--line); }
.pillar__grid { display: grid; grid-template-columns: 1.1fr 1fr; gap: 64px; align-items: center; }
.pillar--flip .pillar__text { order: 2; }
.pillar__idx { display: flex; align-items: baseline; gap: 16px; margin: 0 0 32px; }
.pillar__idx span { font-family: var(--mono); font-size: 13px; color: var(--sky); letter-spacing: .1em; }
.pillar__idx b { font-size: 18px; letter-spacing: .3em; font-weight: 700; }
html[data-lang="en"] .pillar__idx i, html[data-lang="en"] .field h3 i { display: none; }
.pillar__idx i { font-style: normal; font-family: var(--mono); font-size: 12px; letter-spacing: .3em; color: var(--dim); }
.pillar__line { font-size: clamp(36px, 5.6vw, 76px); line-height: 1.1; letter-spacing: -0.035em; font-weight: 850; margin: 0 0 28px; }
.pillar__body { font-size: clamp(16px, 1.5vw, 19px); color: var(--muted); max-width: 560px; margin: 0; line-height: 1.85; }
.pillar__note { font-family: var(--mono); font-size: 12px; letter-spacing: .14em; color: var(--dim); margin: 28px 0 0; }
.pillar__art { aspect-ratio: 1; width: 100%; max-width: 460px; justify-self: center; }

/* mind: 呼吸的同心圆 */
.art-mind svg { width: 100%; height: 100%; overflow: visible; }
.art-mind .core { animation: breathe 6s ease-in-out infinite; transform-origin: 200px 200px; }
.art-mind .rings circle { stroke-width: 1; opacity: .5; animation: ripple 6s ease-in-out infinite; transform-origin: 200px 200px; }
.art-mind .rings circle:nth-child(2) { animation-delay: .6s; opacity: .38; }
.art-mind .rings circle:nth-child(3) { animation-delay: 1.2s; opacity: .26; }
.art-mind .rings circle:nth-child(4) { animation-delay: 1.8s; opacity: .14; }
.art-mind .orbit { fill: #fff; animation: spin 40s linear infinite; transform-origin: 200px 200px; }
@keyframes breathe { 0%,100% { transform: scale(.9); opacity: .8; } 50% { transform: scale(1.08); opacity: 1; } }
@keyframes ripple { 0%,100% { transform: scale(1); } 50% { transform: scale(1.04); } }
@keyframes spin { to { transform: rotate(360deg); } }

/* order: 散点归位成网格（点由 JS 生成） */
.art-order { position: relative; }
.art-order i { position: absolute; width: 6px; height: 6px; margin: -3px 0 0 -3px; border-radius: 50%; background: var(--c, #60a5fa); left: var(--x); top: var(--y); transform: translate(var(--dx), var(--dy)); opacity: .35; transition: transform 1.6s cubic-bezier(.2,.8,.2,1) var(--d), opacity 1.6s ease var(--d); }
.art-order.is-in i { transform: none; opacity: .9; }
.art-order::after { content: ""; position: absolute; inset: 6%; border: 1px solid var(--line); border-radius: 4px; pointer-events: none; }

/* craft */
.pillar--wide .pillar__body { margin-bottom: 72px; }
.fields { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(3, 1fr); border-top: 1px solid var(--line); }
.field { position: relative; padding: 40px 32px 44px 0; }
.field + .field { padding-left: 32px; border-left: 1px solid var(--line); }
.field::before { content: ""; position: absolute; top: -1px; left: 0; right: 0; height: 2px; background: linear-gradient(90deg, var(--c1), var(--c2)); transform: scaleX(0); transform-origin: left; transition: transform .6s cubic-bezier(.2,.8,.2,1); }
.field:hover::before, .field.is-in::before { transform: scaleX(1); }
.field.is-in::before { transition-delay: .3s; }
.field__no { font-family: var(--mono); font-size: 12px; color: var(--dim); letter-spacing: .2em; }
.field h3 { margin: 18px 0 18px; display: flex; align-items: baseline; gap: 14px; }
.field h3 b { font-size: clamp(36px, 4vw, 52px); font-weight: 850; letter-spacing: -.02em; background: linear-gradient(90deg, var(--c1), var(--c2)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.field h3 i { font-style: normal; font-family: var(--mono); font-size: 11px; letter-spacing: .3em; color: var(--dim); }
.field__line { font-size: 19px; line-height: 1.55; margin: 0 0 20px; color: var(--text); font-weight: 600; }
.field__prod { font-family: var(--mono); font-size: 12px; color: var(--muted); letter-spacing: .08em; margin: 0; }

/* loop */
.loop { padding: 120px 0 140px; background: radial-gradient(50% 60% at 25% 50%, rgba(99, 102, 241, .12), transparent 70%); }
.loop__grid { display: grid; grid-template-columns: 1fr 1.3fr; gap: 72px; align-items: center; }
.loop__art { max-width: 360px; width: 100%; justify-self: center; }
.loop__art svg { width: 100%; overflow: visible; }
.loop__ring { stroke-dasharray: 4 6; animation: spin 80s linear infinite; transform-origin: 160px 160px; }
.loop__runner { filter: drop-shadow(0 0 8px #a5b4fc); }
.loop__nodes circle { fill: var(--bg); stroke: #c7d2fe; stroke-width: 1.5; }
.loop__labels text { fill: var(--muted); letter-spacing: .2em; font-family: var(--sans); }
.loop__line { font-size: clamp(32px, 4.4vw, 58px); line-height: 1.15; letter-spacing: -0.03em; font-weight: 850; margin: 0 0 24px; }

/* proof strip */
.proof { border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); overflow: hidden; padding: 26px 0; mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent); -webkit-mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent); }
.proof__track { display: flex; width: max-content; animation: marquee 48s linear infinite; }
.proof:hover .proof__track { animation-play-state: paused; }
.proof__list { list-style: none; display: flex; margin: 0; padding: 0; }
.proof__list li { display: flex; align-items: baseline; gap: 10px; padding: 0 44px; white-space: nowrap; position: relative; }
.proof__list li::after { content: "◆"; position: absolute; right: -5px; font-size: 8px; color: var(--dim); top: 50%; transform: translateY(-50%); }
.proof__list b { font-size: 22px; font-weight: 800; letter-spacing: -.01em; }
.proof__list span { font-size: 14px; color: var(--muted); }
@keyframes marquee { to { transform: translateX(-50%); } }

/* work */
.work { padding: 160px 0 120px; }
.work__line { font-size: clamp(36px, 5.6vw, 76px); line-height: 1.1; letter-spacing: -0.035em; font-weight: 850; margin: 0 0 64px; }
.ways { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; }
.ways li { padding: 32px 32px 32px 0; border-top: 1px solid var(--line-2); }
.ways li + li { padding-left: 32px; }
.ways span { font-family: var(--mono); font-size: 12px; color: var(--sky); letter-spacing: .14em; }
.ways h3 { font-size: 28px; margin: 14px 0 10px; font-weight: 800; letter-spacing: .02em; }
.ways p { margin: 0; color: var(--muted); font-size: 16px; }

/* contact */
.contact { padding: 120px 0 140px; position: relative; overflow: hidden; }
.contact::before { content: ""; position: absolute; width: 760px; height: 760px; left: -280px; bottom: -340px; background: radial-gradient(circle, rgba(74, 84, 255, .26), transparent 65%); filter: blur(40px); z-index: -1; }
.contact__grid { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: start; }
.contact__line { font-size: clamp(32px, 4.4vw, 58px); line-height: 1.15; letter-spacing: -0.03em; font-weight: 850; margin: 0 0 24px; }
.contact .pillar__body { margin-bottom: 40px; }
.mails { list-style: none; padding: 0; margin: 0 0 32px; border-top: 1px solid var(--line); }
.mails li { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 16px; padding: 16px 0; border-bottom: 1px solid var(--line); }
.mails span { flex: 0 0 120px; color: var(--muted); font-size: 14px; }
.mails a { font-family: var(--mono); font-size: 16px; color: #fff; }
.mails a[href]:hover { color: var(--sky); }
.mails em { font-style: normal; background: none; color: var(--dim); -webkit-text-fill-color: currentColor; font-size: 12px; border: 1px dashed var(--line-2); border-radius: 999px; padding: 2px 10px; margin-left: auto; }
.mails [data-reserved] a { color: var(--dim); }
.qrs { display: flex; gap: 20px; flex-wrap: wrap; }
.qrs figure { margin: 0; text-align: center; }
.qrs img { width: 112px; height: 112px; border-radius: 12px; background: #fff; padding: 8px; }
.qrs figcaption { font-size: 12px; color: var(--muted); margin-top: 8px; }

.form { padding: 36px; border-radius: 24px; border: 1px solid var(--line-2); background: linear-gradient(180deg, rgba(255,255,255,.06), rgba(255,255,255,.02)); backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px); box-shadow: 0 40px 120px -50px rgba(74, 84, 255, .7); }
.form__title { font-size: 24px; margin: 0 0 4px; font-weight: 800; }
.form > .muted { margin: 0 0 24px; font-size: 14px; }
.form__row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.form label { display: block; margin: 0 0 14px; }
.form label > span { display: block; font-size: 13px; color: var(--muted); margin: 0 0 6px; }
.form input, .form select, .form textarea { width: 100%; border: 1px solid var(--line-2); background: rgba(6, 7, 26, .6); border-radius: 10px; padding: 12px 14px; font-size: 15px; outline: none; transition: border-color .2s, box-shadow .2s; }
.form select { appearance: none; -webkit-appearance: none; background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%); background-position: calc(100% - 20px) 50%, calc(100% - 15px) 50%; background-size: 5px 5px; background-repeat: no-repeat; padding-right: 36px; }
.form select option { background: var(--bg-2); }
.form textarea { resize: vertical; min-height: 120px; }
.form input:focus, .form select:focus, .form textarea:focus { border-color: var(--sky); box-shadow: 0 0 0 4px rgba(56, 189, 248, .15); }
.form .is-invalid { border-color: var(--err) !important; }
.form .hp { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }
.form__status { min-height: 1.5em; margin: 12px 0 0; font-size: 14px; }
.form__status.ok { color: var(--ok); }
.form__status.err { color: var(--err); }

/* footer */
.footer { border-top: 1px solid var(--line); padding: 72px 0 40px; }
.footer__slogan { font-size: clamp(26px, 3.6vw, 44px); font-weight: 800; letter-spacing: -.02em; margin: 0 0 48px; background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.footer__meta { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 16px 32px; font-size: 14px; color: var(--muted); }
.footer__meta p { margin: 0; font-size: 13px; }
.footer__brand { display: flex; align-items: center; gap: 12px; }
.footer__links { display: flex; flex-wrap: wrap; gap: 6px 22px; }
.footer__links a:hover { color: #fff; }

/* reveal */
.js .reveal { opacity: 0; transform: translateY(24px); transition: opacity .9s ease, transform .9s cubic-bezier(.2,.8,.2,1); }
.js .reveal.is-in { opacity: 1; transform: none; }
.mf li.reveal:nth-child(2) { transition-delay: .12s; }
.mf li.reveal:nth-child(3) { transition-delay: .24s; }
.fields .reveal:nth-child(2), .ways .reveal:nth-child(2) { transition-delay: .12s; }
.fields .reveal:nth-child(3), .ways .reveal:nth-child(3) { transition-delay: .24s; }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  :root { --gutter: 20px; }
  .nav__links { position: fixed; top: 68px; left: 0; right: 0; flex-direction: column; gap: 0; padding: 8px var(--gutter) 20px; background: var(--bg); box-shadow: 0 30px 60px rgba(0,0,0,.6); border-bottom: 1px solid var(--line); transform: translateY(-8px); opacity: 0; pointer-events: none; transition: opacity .2s, transform .2s; }
  .nav.is-open .nav__links { opacity: 1; transform: none; pointer-events: auto; }
  .nav.is-open { background: var(--bg); }
  .nav__links a { padding: 14px 4px; font-size: 16px; border-bottom: 1px solid var(--line); border-radius: 0; }
  .nav__burger { display: block; }
  .nav__cta { display: none; }
  .pillar { padding: 100px 0; }
  .pillar__grid, .loop__grid, .contact__grid { grid-template-columns: 1fr; gap: 48px; }
  .pillar--flip .pillar__text { order: 0; }
  .pillar__art { max-width: 320px; }
  .loop__art { max-width: 280px; }
  .fields, .ways { grid-template-columns: 1fr; }
  .field, .field + .field { padding: 32px 0; border-left: 0; }
  .field + .field { border-top: 1px solid var(--line); }
  .ways li, .ways li + li { padding: 28px 0; }
  .manifesto, .work { padding: 110px 0 90px; }
}
@media (max-width: 600px) {
  :root { --gutter: 16px; }
  .brand__text i { display: none; }
  .hero__title { font-size: clamp(38px, 11.5vw, 52px); }
  html[data-lang="zh"] .hero__title { font-size: clamp(28px, 8.8vw, 48px); }
  .hero__sub br { display: none; }
  .pillar__line, .work__line { font-size: clamp(30px, 9vw, 40px); }
  .form { padding: 24px 18px; }
  .form__row { grid-template-columns: 1fr; gap: 0; }
  .mails span { flex-basis: 100%; }
  .mails em { margin-left: 0; }
  .proof__list li { padding: 0 28px; }
  .proof__list b { font-size: 18px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .js .reveal { opacity: 1; transform: none; }
  .art-order i { transform: none; opacity: .9; }
}