:root {
  color-scheme: dark;
  --bg: #191b1e;
  --text: #eeeee7;
  --muted: #acb1a8;
  --line: #383d3b;
  --mint: #c5e6b1;
  --coral: #f0a18d;
  --yellow: #f4d57b;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans", "Noto Sans CJK KR", sans-serif;
}
* { box-sizing: border-box; letter-spacing: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 32px; }
body { margin: 0; background: var(--bg); color: var(--text); font-family: var(--font); font-size: 16px; line-height: 1.65; -webkit-font-smoothing: antialiased; }
button, input, select { font: inherit; }
a { color: inherit; text-decoration: none; text-underline-offset: 5px; }
button, select, summary { -webkit-tap-highlight-color: transparent; }
button, select { cursor: pointer; }
button { color: inherit; }
button:disabled { cursor: default; }
img { display: block; max-width: 100%; height: auto; }
svg { flex-shrink: 0; width: 20px; height: 20px; }
h1, h2, h3, p { margin: 0; }
h1, h2, h3 { line-height: 1.25; font-weight: 500; text-wrap: balance; }
button, a, select, input, summary { outline-offset: 6px; }
:focus-visible { outline: 2px solid var(--yellow); }
::selection { color: var(--bg); background: var(--mint); }
[hidden] { display: none !important; }
.shell { width: min(1280px, calc(100% - 112px)); margin-inline: auto; }
.mint { color: var(--mint); }
.coral { color: var(--coral); }
.yellow { color: var(--yellow); }
.math-small, .hero-equation, .work-symbol, .plan-symbol, .quiet-math, .contact-symbol { font-family: "Times New Roman", "STIX Two Math", serif; font-style: italic; font-weight: 400; }
.math-small { font-size: 20px; white-space: nowrap; }
.skip-link { position: fixed; top: 10px; left: 24px; z-index: 100; background: var(--mint); color: var(--bg); padding: 10px 20px; transform: translateY(-180%); opacity: 0; pointer-events: none; }
.skip-link:focus { transform: none; opacity: 1; pointer-events: auto; }
.site-header { display: flex; align-items: center; gap: 40px; height: 80px; border-bottom: 1px solid var(--line); position: relative; z-index: 3; }
.brand { display: flex; align-items: center; gap: 10px; font-size: 22px; font-weight: 550; white-space: nowrap; }
.brand img { border-radius: 8px; width: 36px; height: 36px; }
.main-nav { display: flex; align-items: center; gap: 30px; margin-left: auto; }
.main-nav a { color: var(--muted); font-size: 14px; padding-block: 12px; white-space: nowrap; }
.main-nav a:hover, .main-nav a[aria-current], .footer-links a:hover { color: var(--mint); }
.language-picker { display: flex; align-items: center; gap: 7px; }
.language-picker svg { width: 17px; color: var(--muted); }
.language-picker select { border: 0; background: var(--bg); color: var(--text); font-size: 13px; height: 44px; max-width: 112px; padding-inline: 3px; }
.hero { position: relative; height: min(700px, calc(100svh - 270px)); min-height: 500px; isolation: isolate; }
#math-scene { position: absolute; inset: 0; z-index: -1; touch-action: pan-y; }
#math-scene canvas { display: block; width: 100%; height: 100%; cursor: grab; }
#math-scene canvas:active { cursor: grabbing; }
.scene-fallback { display: block; width: 100%; height: 100%; }
.scene-fallback img { width: 100%; height: 100%; object-fit: cover; }
.hero-copy { position: relative; padding-top: 56px; pointer-events: none; }
.hero-copy h1 { font-size: 88px; max-width: 540px; line-height: 1.07; margin-bottom: 24px; }
:lang(zh) .hero-copy h1 { font-size: 112px; }
:lang(ja) .hero-copy h1, :lang(ko) .hero-copy h1 { font-size: 72px; }
.hero-tagline { max-width: 400px; font-size: 23px; line-height: 1.65; text-wrap: balance; }
.hero-description { font-size: 15px; color: var(--muted); max-width: 370px; margin-top: 10px; }
.hero-copy .button { pointer-events: auto; margin-top: 28px; }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 20px; min-height: 50px; padding: 12px 22px; border: 1px solid transparent; border-radius: 4px; font-size: 15px; line-height: 1.4; transition: background .2s, transform .2s; }
.button:hover { transform: translateY(-2px); }
.primary { background: var(--mint); color: var(--bg); }
.primary:hover { background: #d8efcb; }
.scene-meta { position: absolute; right: max(56px, calc((100% - 1280px) / 2)); top: 28px; display: flex; gap: 22px; align-items: center; color: var(--muted); font-size: 13px; }
.scene-meta .math-small { color: var(--coral); }
.hero-equation { position: absolute; left: max(56px, calc((100% - 1280px) / 2)); bottom: 146px; font-size: 44px; color: var(--muted); }
.scene-controls { position: absolute; bottom: 14px; left: 0; right: 0; display: flex; justify-content: space-between; align-items: center; gap: 32px; border-top: 1px solid var(--line); padding-top: 16px; }
.scene-controls > p { display: flex; gap: 22px; align-items: center; font-size: 14px; }
.scene-controls > p .math-small { color: var(--mint); }
.timeline { display: flex; align-items: center; gap: 15px; width: min(420px, 45%); }
.icon-button { width: 44px; height: 44px; display: inline-flex; justify-content: center; align-items: center; flex-shrink: 0; background: transparent; border: 1px solid var(--line); border-radius: 50%; }
.icon-button:hover { background: #303632; border-color: var(--mint); }
.icon-button svg { width: 18px; height: 18px; }
.timeline .math-small { color: var(--muted); }
input[type="range"] { width: 100%; min-width: 50px; height: 40px; accent-color: var(--mint); cursor: ew-resize; background: transparent; -webkit-appearance: none; }
input[type="range"]::-webkit-slider-runnable-track { height: 2px; background: #707c69; }
input[type="range"]::-moz-range-track { height: 2px; background: #707c69; }
input[type="range"]::-webkit-slider-thumb { -webkit-appearance: none; width: 14px; height: 14px; border-radius: 50%; margin-top: -6px; background: var(--mint); border: 3px solid var(--bg); outline: 1px solid var(--mint); }
input[type="range"]::-moz-range-thumb { width: 10px; height: 10px; border-radius: 50%; background: var(--mint); border: 3px solid var(--bg); outline: 1px solid var(--mint); }
.availability { display: flex; gap: 10px; align-items: center; color: var(--muted); font-size: 12px; padding-block: 8px 20px; }
.availability svg { width: 15px; height: 15px; }
.section-space { padding-block: 100px; }
.section-heading { margin-bottom: 52px; max-width: 760px; }
.section-heading h2 { font-size: 38px; margin-bottom: 14px; }
.section-heading > p { color: var(--muted); font-size: 17px; }
.work-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 52px; }
.work-item { min-width: 0; display: flex; flex-direction: column; align-items: flex-start; }
.work-heading { width: 100%; }
.work-symbol { display: block; font-size: 36px; height: 54px; }
.work-item h3 { font-size: 22px; min-height: 56px; }
.work-item > p { font-size: 15px; color: var(--muted); line-height: 1.9; min-height: 94px; margin-top: 8px; margin-bottom: 32px; }
.app-screen { width: min(100%, 280px); aspect-ratio: 660 / 1434; object-fit: contain; align-self: center; border: 1px solid #42474a; border-radius: 30px; background: var(--bg); box-shadow: 0 24px 40px #0003; }
.quiet-band { border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.quiet-inner { padding-block: 64px; display: grid; grid-template-columns: 1fr 1.2fr; gap: 80px; align-items: center; }
.quiet-math { font-size: 64px; line-height: 1.2; white-space: nowrap; }
.quiet-math span { color: var(--mint); }
.quiet-inner h2 { font-size: 27px; margin-bottom: 14px; }
.quiet-inner p { color: var(--muted); max-width: 580px; margin-bottom: 18px; }
.text-link { display: inline-flex; align-items: center; gap: 8px; color: var(--mint); font-size: 14px; }
.text-link:hover { text-decoration: underline; }
.text-link svg { width: 17px; }
.plans { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; }
.plan { border-top: 1px solid var(--line); padding-block: 28px; }
.plan-title { display: flex; align-items: center; justify-content: space-between; gap: 20px; min-height: 48px; }
.plan-title h3 { font-size: 24px; }
.plan-symbol { font-size: 34px; white-space: nowrap; }
.plan-note { color: var(--muted); font-size: 14px; margin-top: 12px; }
.plan ul { padding: 0; margin: 28px 0 0; list-style: none; }
.plan li { display: flex; align-items: flex-start; gap: 14px; margin-block: 16px; }
.plan li svg { color: var(--mint); margin-top: 4px; width: 17px; height: 17px; }
.purchase-note { border-top: 1px solid var(--line); padding-top: 24px; display: flex; align-items: flex-start; justify-content: space-between; gap: 30px; }
.purchase-note p { font-size: 13px; color: var(--muted); max-width: 720px; }
.purchase-note .text-link { flex-shrink: 0; }
.closing { padding-block: 72px 90px; text-align: center; }
.closing img { margin: 0 auto 26px; border-radius: 16px; }
.closing h2 { font-size: 42px; }
.supported-languages { color: var(--muted); font-size: 13px; margin-block: 18px 28px; }
.release-status { display: inline-flex; align-items: center; gap: 10px; color: var(--mint); font-size: 15px; }
.site-footer { border-top: 1px solid var(--line); padding-block: 36px 24px; display: grid; grid-template-columns: 1fr auto; gap: 32px; }
.footer-brand > a { font-size: 23px; display: flex; gap: 12px; align-items: center; }
.footer-brand p { color: var(--muted); font-size: 12px; margin-top: 8px; }
.footer-links { display: flex; align-items: flex-start; flex-wrap: wrap; gap: 28px; font-size: 13px; padding-top: 8px; }
.footer-bottom { grid-column: 1 / -1; display: flex; justify-content: space-between; gap: 20px; font-size: 12px; color: var(--muted); padding-top: 16px; }
.document-main { padding-block: 72px 100px; }
.document-header { max-width: 800px; margin-bottom: 64px; }
.document-header h1 { font-size: 60px; margin-bottom: 24px; }
.document-intro { font-size: 26px; color: var(--mint); margin-bottom: 16px; }
.document-summary { max-width: 700px; font-size: 17px; color: var(--muted); line-height: 1.9; }
.document-date { color: var(--muted); font-size: 12px; margin-top: 24px; }
.document-layout { display: grid; grid-template-columns: 260px minmax(0, 730px); gap: 80px; }
.document-aside { align-self: start; position: sticky; top: 32px; }
.document-aside nav { display: flex; flex-direction: column; gap: 18px; font-size: 14px; color: var(--muted); margin-bottom: 36px; }
.document-aside nav a:hover { color: var(--mint); }
.policy-body { min-width: 0; }
.policy-body section { margin-bottom: 44px; }
.policy-body h2 { font-size: 23px; margin-bottom: 16px; }
.policy-body p { color: #c2c6be; line-height: 1.95; margin-bottom: 16px; overflow-wrap: break-word; }
.support-layout { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.5fr); gap: 100px; }
.contact-panel { align-self: start; position: sticky; top: 32px; }
.contact-symbol { display: block; font-size: 80px; line-height: 1.1; margin-bottom: 22px; }
.contact-panel h2 { font-size: 26px; margin-bottom: 16px; }
.contact-panel > p { color: var(--muted); font-size: 15px; line-height: 1.9; }
.email-row { display: flex; align-items: center; flex-wrap: wrap; gap: 10px; margin-top: 20px; }
.email-row > a { font-size: 20px; color: var(--mint); overflow-wrap: anywhere; }
.email-row > a:hover { text-decoration: underline; }
.contact-panel .copy-status { min-height: 34px; color: var(--mint); font-size: 12px; margin-block: 4px 8px; }
.faq h2 { font-size: 26px; margin-bottom: 25px; }
.faq details { border-top: 1px solid var(--line); }
.faq details:last-of-type { border-bottom: 1px solid var(--line); }
.faq summary { display: flex; justify-content: space-between; align-items: center; gap: 24px; padding-block: 23px; list-style: none; font-size: 17px; cursor: pointer; line-height: 1.7; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary svg { color: var(--mint); transition: transform .2s; }
.faq details[open] summary svg { transform: rotate(45deg); }
.faq details > div { padding-bottom: 24px; }
.faq details p { color: var(--muted); font-size: 15px; line-height: 1.95; }
.faq details .text-link { margin-top: 16px; }
.faq-privacy { margin-top: 28px; }
@media (min-width: 1600px) {
  .hero-copy { padding-top: 78px; }
}
@media (min-width: 761px) and (max-height: 850px) {
  .hero-equation { display: none; }
}
@media (max-width: 1100px) {
  .shell { width: calc(100% - 64px); }
  .site-header { gap: 24px; }
  .hero-copy h1 { font-size: 70px; }
  :lang(zh) .hero-copy h1 { font-size: 92px; }
  :lang(ja) .hero-copy h1, :lang(ko) .hero-copy h1 { font-size: 58px; }
  .hero-tagline { max-width: 330px; font-size: 21px; }
  .hero-description { max-width: 290px; }
  .hero-equation { left: 32px; font-size: 36px; }
  .scene-meta { right: 32px; }
  .work-grid { gap: 28px; }
  .work-item h3 { font-size: 19px; }
  .work-item > p { min-height: 122px; font-size: 14px; }
  .quiet-inner { gap: 40px; }
  .quiet-math { font-size: 52px; }
  .document-layout { grid-template-columns: 210px minmax(0, 1fr); gap: 40px; }
  .support-layout { gap: 48px; }
}
@media (max-width: 760px) {
  .shell { width: calc(100% - 40px); }
  .site-header { height: 68px; gap: 16px; }
  .brand { font-size: 18px; gap: 7px; }
  .brand img { width: 30px; height: 30px; }
  .main-nav { gap: 16px; }
  .main-nav .nav-explore, .main-nav .nav-plus { display: none; }
  .main-nav a { font-size: 13px; }
  .language-picker { gap: 0; }
  .language-picker svg { display: none; }
  .language-picker select { max-width: 97px; font-size: 12px; }
  .hero { height: min(650px, calc(100svh - 225px)); min-height: 480px; }
  .hero-copy { padding-top: 36px; }
  .hero-copy h1, :lang(ja) .hero-copy h1, :lang(ko) .hero-copy h1 { font-size: 48px; margin-bottom: 14px; }
  :lang(zh) .hero-copy h1 { font-size: 64px; }
  .hero-tagline { max-width: 340px; font-size: 18px; line-height: 1.6; }
  .hero-description { max-width: 330px; font-size: 13px; margin-top: 7px; }
  .hero-copy .button { margin-top: 18px; min-height: 44px; padding: 10px 16px; font-size: 13px; gap: 20px; }
  .scene-meta { top: auto; right: 20px; bottom: 112px; font-size: 11px; gap: 12px; }
  .scene-meta .math-small { font-size: 15px; }
  .hero-equation { display: none; }
  .scene-controls { bottom: 10px; display: block; padding-top: 10px; }
  .scene-controls > p { justify-content: space-between; font-size: 12px; }
  .scene-controls > p .math-small { font-size: 18px; }
  .timeline { width: 100%; gap: 13px; margin-top: 6px; }
  .timeline .icon-button { width: 36px; height: 36px; }
  .availability { font-size: 10px; gap: 6px; padding-bottom: 10px; }
  .availability svg { width: 13px; }
  .section-space { padding-block: 66px; }
  .works { padding-top: 36px; }
  .section-heading { margin-bottom: 36px; }
  .section-heading h2 { font-size: 29px; }
  .section-heading p { font-size: 15px; }
  .work-grid { grid-template-columns: 1fr; gap: 60px; }
  .work-heading { display: flex; align-items: center; gap: 18px; }
  .work-symbol { height: auto; width: 52px; font-size: 32px; flex-shrink: 0; }
  .work-item h3 { min-height: 0; font-size: 21px; }
  .work-item > p { min-height: 0; margin-block: 12px 26px; max-width: 520px; font-size: 15px; }
  .app-screen { width: 256px; }
  .quiet-inner { grid-template-columns: 1fr; gap: 28px; padding-block: 46px; }
  .quiet-math { font-size: 48px; }
  .quiet-inner h2 { font-size: 25px; }
  .quiet-inner p { font-size: 15px; }
  .plans { grid-template-columns: 1fr; gap: 10px; }
  .plan { padding-block: 20px; }
  .plan-title h3 { font-size: 22px; }
  .plan li { font-size: 15px; }
  .purchase-note { display: block; }
  .purchase-note .text-link { margin-top: 16px; }
  .closing { padding-block: 30px 66px; }
  .closing h2 { font-size: 30px; }
  .supported-languages { font-size: 11px; line-height: 2; }
  .site-footer { grid-template-columns: 1fr; gap: 24px; }
  .footer-links { gap: 24px; padding: 0; }
  .footer-bottom { font-size: 11px; gap: 12px; flex-wrap: wrap; }
  .document-main { padding-block: 46px 64px; }
  .document-header { margin-bottom: 38px; }
  .document-header h1 { font-size: 37px; }
  .document-intro { font-size: 22px; }
  .document-summary { font-size: 15px; }
  .document-layout { display: block; }
  .document-aside { position: static; border-block: 1px solid var(--line); padding-block: 24px; margin-bottom: 40px; }
  .document-aside nav { display: grid; grid-template-columns: 1fr 1fr; gap: 14px 24px; margin-bottom: 20px; font-size: 12px; }
  .policy-body h2 { font-size: 22px; }
  .policy-body p { font-size: 15px; }
  .support-layout { grid-template-columns: 1fr; gap: 56px; }
  .contact-panel { position: static; }
  .contact-symbol { display: none; }
  .contact-panel h2, .faq h2 { font-size: 23px; }
  .faq summary { font-size: 16px; gap: 16px; }
}
@media (max-width: 760px) and (max-height: 750px) {
  .hero-copy { padding-top: 24px; }
  .hero-description { display: none; }
  .hero-tagline { font-size: 16px; }
  .scene-meta { bottom: 106px; }
}
@media (max-width: 760px) and (max-height: 620px) {
  .hero { min-height: 420px; }
  .hero-copy h1, :lang(zh) .hero-copy h1, :lang(ja) .hero-copy h1, :lang(ko) .hero-copy h1 { font-size: 42px; margin-bottom: 8px; }
  .hero-copy .button { margin-top: 12px; }
  .scene-meta { display: none; }
  .works { padding-top: 24px; }
}
@media (max-width: 370px) {
  .site-header { gap: 8px; }
  .brand { font-size: 16px; }
  .brand img { width: 26px; height: 26px; }
  .language-picker select { max-width: 89px; }
  .hero-copy h1 { font-size: 42px; }
  :lang(ja) .hero-copy h1, :lang(ko) .hero-copy h1 { font-size: 44px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; }
  .button:hover { transform: none; }
}