:root {
  
  --spacing: 0.25rem;
  --space-1: 0.25rem;  --space-2: 0.5rem;  --space-3: 0.75rem; --space-4: 1rem;
  --space-5: 1.5rem;   --space-6: 2rem;    --space-8: 3rem;
  --space-12: 4rem;    --space-16: clamp(3.5rem, 2.2rem + 5.5vw, 5.5rem);

  
  --container-wrap: 1320px;   
  --gutter: clamp(1.25rem, 0.9rem + 1.5vw, 2rem);
  --nav-h: 60px;
  --rule-width: 1px;

  
  --text-display: clamp(2.25rem, 1.6273rem + 2.6564vw, 3.75rem);
  --text-h2:      clamp(1.5rem,  1.3757rem + 0.5304vw, 1.8rem);
  --text-h3:      clamp(1.125rem,1.0991rem + 0.1105vw, 1.1875rem);
  --text-lead:    clamp(1.0625rem, 1.0107rem + 0.2210vw, 1.1875rem);
  --text-body:    1rem;
  --text-sm:      0.9375rem;
  --text-xs:      0.8125rem;
  --text-brand:   1.0625rem;

  --leading-tight: 1.08;
  --leading-normal: 1.55;
  --leading-relaxed: 1.65;

  --tracking-display: -0.022em;
  --tracking-heading: -0.014em;
  --tracking-normal:  -0.004em;
  --tracking-label:    0.06em;
  --tracking-brand:   -0.02em;
  --tracking-button:   0;

  --font-weight-display: 600;
  --font-weight-normal: 400;
  --font-weight-semibold: 600;
  --font-weight-brand: 600;

  --display-transform: none;
  --label-transform: uppercase;
  --brand-transform: none;
  --button-transform: none;
  --display-measure: 20ch;

  --font-display: var(--font-ui);
  --font-label:   var(--font-ui);
  --font-ui:   -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;

  
  --radius-sm: 4px; --radius-md: 6px; --radius-lg: 10px; --radius-xl: 14px; --radius-pill: 999px;

  
  --shadow-raised: none;
  --shadow-pop: none;
  --shadow-button: none;

  
  --btn-pad-x: var(--space-5);
  --btn-pad-y: 0.6875rem;
  --mark-display: grid;
  --logo-h: 14px;      
  

  
  --color-label: var(--color-fg-muted);
}

*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: auto;
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-fg);
  font-family: var(--font-ui);
  font-size: var(--text-body);
  line-height: var(--leading-normal);
  letter-spacing: var(--tracking-normal);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 { margin: 0; font-weight: var(--font-weight-display); }

h2, h3, h4 { text-wrap: balance; }
h2 {
  font-size: var(--text-h2);
  line-height: var(--leading-tight);
  letter-spacing: var(--tracking-heading);
  max-width: var(--measure-heading, none);
}
h3, h4 {
  font-size: var(--text-h3);
  line-height: var(--leading-tight);
  letter-spacing: var(--tracking-heading);
}
p, dl, dd { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
a { color: inherit; text-decoration: none; }

main p > a:not([class]),
footer p > a:not([class]) {
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
  text-decoration-color: var(--color-line-strong);
}
main p > a:not([class]):hover,
footer p > a:not([class]):hover { text-decoration-color: currentColor; }
img, svg { max-width: 100%; height: auto; display: block; }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}
::selection { background: var(--color-accent); color: var(--color-accent-fg); }

.wrap {
  width: 100%;
  max-width: var(--container-wrap);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding-block: var(--space-16); }
.section + .section { border-top: var(--rule-width) solid var(--color-line); }
.section--surface { background: var(--color-surface); }

.eyebrow {
  display: block;
  font-family: var(--font-label);
  font-size: var(--text-xs);
  font-weight: var(--font-weight-semibold);
  letter-spacing: var(--tracking-label);
  text-transform: var(--label-transform);
  color: var(--color-label);
  margin-bottom: var(--space-3);
}

.nav {
  position: sticky; top: 0; z-index: 50;
  height: var(--nav-h);
  background: color-mix(in srgb, var(--color-bg) 84%, transparent);
  -webkit-backdrop-filter: saturate(180%) blur(18px);
          backdrop-filter: saturate(180%) blur(18px);
  border-bottom: var(--rule-width) solid transparent;
  display: flex; align-items: center;
  transition: border-color 200ms ease;
}
.nav.is-scrolled { border-bottom-color: var(--color-line); }
@supports not (backdrop-filter: blur(1px)) { .nav { background: var(--color-bg); } }
.nav__inner { display: flex; align-items: center; justify-content: space-between; gap: var(--space-6); width: 100%; }
.nav__brand {
  display: inline-flex; align-items: center; gap: var(--space-2);
  font-family: var(--font-display);
  font-size: var(--text-brand);
  font-weight: var(--font-weight-brand);
  letter-spacing: var(--tracking-brand);
  text-transform: var(--brand-transform);
  color: var(--color-fg);
}

.nav__logo {
  height: var(--logo-h);
  aspect-ratio: 1582.5 / 118.25;
  background-color: var(--logo-color, var(--color-fg));
  -webkit-mask: url("brand/sophon-wordmark-tight.svg") no-repeat center / contain;
          mask: url("brand/sophon-wordmark-tight.svg") no-repeat center / contain;
}

@media (prefers-reduced-motion: no-preference) {
  .nav__logo {
    background-color: transparent;
    background-image: linear-gradient(100deg,
      var(--logo-color, var(--color-fg)) 0 42%,
      color-mix(in srgb, var(--logo-color, var(--color-fg)) 18%, #fff) 50%,
      var(--logo-color, var(--color-fg)) 56% 100%);
    background-size: 300% 100%;
    background-position: 100% 0;
    animation: wordmark-sheen 4.4s cubic-bezier(.32, .2, .25, 1) infinite;
  }
  @keyframes wordmark-sheen { 0%, 38% { background-position: 100% 0; } 100% { background-position: 0% 0; } }
}
.nav__brand--logo {
  gap: 0;
  
  min-height: 44px;
}

.nav__links { display: flex; align-items: center; gap: var(--space-1); }
.nav__link {
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  color: var(--color-fg-muted);
  transition: color 150ms ease, background-color 150ms ease;
  white-space: nowrap;
}
.nav__link:hover { color: var(--color-fg); background: var(--color-surface-raised); }

.btn {
  display: inline-flex; align-items: center; gap: var(--space-2);
  padding: var(--btn-pad-y) var(--btn-pad-x);
  border: var(--rule-width) solid transparent;
  border-radius: var(--radius-md);
  font: inherit;
  font-family: var(--font-ui);
  font-size: var(--text-sm);
  font-weight: var(--font-weight-semibold);
  letter-spacing: var(--tracking-button);
  text-transform: var(--button-transform);
  cursor: pointer; white-space: nowrap;
  transition: background-color 150ms ease, border-color 150ms ease, color 150ms ease;
}
.btn--primary { background: var(--color-accent); color: var(--color-accent-fg); box-shadow: var(--shadow-button); }
.btn--primary:hover { background: var(--color-accent-hover); }
.btn--secondary {
  background: var(--color-bg);
  color: var(--color-fg);
  border-color: var(--color-control);
  box-shadow: var(--shadow-button);
}
.btn--secondary:hover { background: var(--color-surface-raised); }

.link-arrow {
  display: inline-flex; align-items: center; gap: var(--space-2);
  color: var(--color-accent);
  font-weight: var(--font-weight-semibold);
  font-size: var(--text-sm);
  
  min-height: 24px;
}
.link-arrow::after { content: "→"; transition: transform 150ms ease; }
.link-arrow:hover::after { transform: translateX(3px); }

.hero { padding-block: var(--space-16) var(--space-12); }
.hero__title {
  font-family: var(--font-display);
  font-size: var(--text-display);
  
  line-height: var(--leading-hero, 1.08);
  letter-spacing: var(--tracking-display);
  font-weight: var(--font-weight-display);
  text-transform: var(--display-transform);
  max-width: var(--display-measure);
  text-wrap: balance;
}

.hero__title em { font-style: normal; color: var(--color-fg-muted); }
.hero__sub {
  margin-top: var(--space-5);
  font-size: var(--text-lead);
  line-height: var(--leading-relaxed);
  color: var(--color-fg-muted);
  max-width: 56ch;
}
@keyframes cue-wave { 0%,100% { transform: scaleY(0.45) } 50% { transform: scaleY(1) } }

.tags { display: flex; flex-wrap: wrap; gap: var(--space-2); }
.tag {
  display: inline-flex; align-items: center;
  padding: 3px var(--space-2);
  border: var(--rule-width) solid var(--color-line-strong);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-fg-muted);
  letter-spacing: 0;
}
.tag--accent { border-color: var(--color-accent-line); background: var(--color-accent-surface); color: var(--color-accent); }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}

@media (max-width: 1000px) {
  .nav__links { display: none; }
  
  :root { --logo-h: 12px; }
}

.facts { margin: var(--space-6) 0 0; max-width: var(--measure-body); }
.facts > div {
  display: grid; grid-template-columns: 11rem minmax(0, 1fr);
  gap: var(--space-4); padding: var(--space-4) 0;
  border-top: 1px solid var(--color-line);
  align-items: baseline;
}
@media (max-width: 640px) { .facts > div { grid-template-columns: 1fr; gap: var(--space-2); } }
.facts dt {
  margin: 0; color: var(--color-fg-muted);
  font-family: var(--font-mono); font-size: var(--text-xs);
  letter-spacing: 0.08em; text-transform: uppercase;
}
.facts dd {
  margin: 0; font-size: var(--text-h3); font-weight: 600;
  letter-spacing: -0.02em; line-height: 1.25; overflow-wrap: anywhere;
}
.facts dd.plain { font-size: var(--text-body); font-weight: 400; letter-spacing: normal; line-height: 1.6; }
.facts dt a { color: var(--color-fg); font-family: var(--font-ui); font-size: var(--text-body);
  font-weight: 600; letter-spacing: normal; text-transform: none;
  display: inline-flex; align-items: center; min-height: 24px;
  text-decoration: underline; text-decoration-thickness: 1px;
  text-underline-offset: 0.18em; text-decoration-color: var(--color-line-strong); }
.facts dt a:hover { text-decoration-color: currentColor; }
.facts dd a { text-decoration: underline; text-decoration-thickness: 1px;
  text-underline-offset: 0.18em; text-decoration-color: var(--color-line-strong); }
.facts dd a:hover { text-decoration-color: currentColor; }
.pkg { font-family: var(--font-mono); font-size: var(--text-xs); letter-spacing: 0;
  color: var(--color-fg-muted); display: block; margin-top: 2px; font-weight: 400; }

::selection { background: var(--color-accent-surface); color: var(--color-fg); }
:focus-visible { outline: 2px solid var(--color-focus); outline-offset: 3px; border-radius: 2px; }
.btn:focus-visible, .nav__link:focus-visible { outline-offset: 2px; }
.num { font-variant-numeric: tabular-nums; }

.section--band { padding-block: var(--space-band); }
.head { text-align: center; display: grid; justify-items: center; gap: var(--space-4); margin-bottom: var(--space-12); }
.head h2 { text-wrap: balance; font-size: var(--text-head, var(--text-h2)); font-weight: var(--font-weight-heading, 700); letter-spacing: var(--tracking-heading);
  line-height: 1.06; max-width: 20ch; margin: 0; }
.head .deck { text-wrap: balance; font-size: var(--text-lead); line-height: 1.5; color: var(--color-fg-muted); max-width: var(--measure-deck); margin: 0; }

.nav .nav__item { position: static; }
.nav__more { display: none; }
.nav__scrim {
  position: fixed; inset: 0; z-index: -1; opacity: 0; pointer-events: none;
  background: rgb(255 255 255 / 0.45);
  -webkit-backdrop-filter: blur(22px) saturate(140%); backdrop-filter: blur(22px) saturate(140%);
  transition: opacity 400ms ease;
}
.nav.is-open .nav__scrim { opacity: 1; pointer-events: auto; }
.nav__panel-inner { display: grid; gap: var(--space-6); }
.nav__h { margin: 0 0 var(--space-3); font-family: var(--font-mono); font-size: var(--text-xs); letter-spacing: 0.04em; text-transform: uppercase; color: var(--color-label); }
.nav__col ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 6px; }
.nav__col a { color: var(--color-fg); text-decoration: none; display: inline-block; padding: 2px 0; border-radius: 4px; }
.nav__col a:hover { color: var(--color-accent); }
.nav__col--big a { font-size: 1.375rem; font-weight: var(--font-weight-semibold); letter-spacing: -0.02em; line-height: 1.25; }
.nav__col--small a { font-size: 0.9375rem; font-weight: 500; }
@media (min-width: 1001px) {
  .nav__panel {
    position: absolute; left: 0; right: 0; top: 100%; display: none; height: 0; overflow: hidden;
    background: var(--color-bg); border-bottom: var(--rule-width) solid var(--color-line);
    box-shadow: 0 30px 60px -30px rgb(29 26 26 / 0.25);
    transition: height 480ms cubic-bezier(0.32, 0.72, 0, 1);
  }
  .nav__panel.is-active { display: block; }
  .nav__panel-inner { grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr) minmax(0, 1fr); column-gap: var(--space-12); padding-block: var(--space-6) var(--space-8); }
  .nav__col li { opacity: 0; transform: translateY(8px); transition: opacity 320ms ease, transform 320ms ease; transition-delay: calc(80ms + var(--i, 0) * 28ms); }
  .nav__item.is-open .nav__col li { opacity: 1; transform: none; }
  .nav__item.is-open > .nav__link { color: var(--color-fg); background: var(--color-surface-raised); }
  .nav__item:focus-within .nav__more, .nav__item.is-open .nav__more { display: inline-grid; place-items: center; width: 28px; height: 28px; margin-left: -4px; border: 0; padding: 0; background: none; color: var(--color-fg-muted); cursor: pointer; vertical-align: middle; }
  .nav__more::before { content: ""; width: 7px; height: 7px; margin-top: -3px; border-right: 1.5px solid currentColor; border-bottom: 1.5px solid currentColor; transform: rotate(45deg); transition: transform 250ms ease; }
  .nav__more[aria-expanded="true"]::before { transform: rotate(225deg); margin-top: 3px; }
  .nav__more:focus-visible { outline: 2px solid var(--color-focus); outline-offset: 2px; border-radius: 6px; }
}
@media (max-width: 1000px) {
  .nav__toggle[aria-expanded="true"] + .nav__links { left: var(--gutter); max-height: calc(100dvh - 92px); overflow-y: auto; overscroll-behavior: contain; }
  .nav .nav__item { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center; }
  .nav__more { display: inline-grid; place-items: center; width: 40px; height: 40px; border: 0; background: none; cursor: pointer; color: var(--color-fg); padding: 0; }
  .nav__more::before { content: ""; width: 8px; height: 8px; margin-top: -4px; border-right: 2px solid currentColor; border-bottom: 2px solid currentColor; transform: rotate(45deg); transition: transform 250ms ease, margin 250ms ease; }
  .nav__more[aria-expanded="true"]::before { transform: rotate(225deg); margin-top: 4px; }
  .nav__more:focus-visible { outline: 2px solid var(--color-focus); outline-offset: 2px; border-radius: 6px; }
  .nav__panel { grid-column: 1 / -1; display: grid; grid-template-rows: 0fr; transition: grid-template-rows 350ms ease; }
  .nav__item.is-open .nav__panel { grid-template-rows: 1fr; }
  
  .nav__panel-inner { overflow: hidden; min-height: 0; padding: 0 var(--space-3); gap: var(--space-4); }
  .nav__item.is-open .nav__panel-inner { padding-bottom: var(--space-3); }
  .nav__item.is-open .nav__panel-inner { padding-top: var(--space-2); }
  .nav__col--big a { font-size: 1.0625rem; }
}

footer.foot { padding-block: var(--space-8) var(--space-6); }
footer.foot .foot__grid { gap: var(--space-6); }
footer.foot .foot__tag { font-size: 0.8125rem; line-height: 1.5; margin-top: var(--space-3); max-width: 28ch; }
footer.foot .foot__label { font-family: inherit; font-size: 0.75rem; font-weight: var(--font-weight-semibold, 600); letter-spacing: 0; color: var(--color-fg); margin: 0 0 var(--space-2); }
footer.foot ul { gap: 2px; }
footer.foot a { font-size: 0.8125rem; line-height: 1.4; min-height: 24px; min-width: 24px; padding-block: 2px; color: var(--color-fg-muted); }
footer.foot .foot__legal { margin-top: var(--space-6); padding-top: var(--space-4); font-size: 0.75rem; line-height: 1.5; }
footer.foot .foot__legal--marks { margin-top: var(--space-2); font-size: 0.6875rem; }

@media (max-width: 640px) { .head h2 br { display: none; } }

@media (min-width: 1600px) { :root { --container-wrap: min(1680px, 86vw); } }

html[lang="ja"], html[lang="ko"], html[lang^="zh"] {
  --tracking-display: 0;
  --tracking-heading: 0;
  --tracking-normal: 0;
  --tracking-brand: 0;
  --leading-tight: 1.28;
  --leading-hero: 1.28;
  --leading-normal: 1.75;
  --leading-relaxed: 1.85;
  --display-measure: 13em;
  --measure-heading: 12em;
  --text-hero: clamp(2.125rem, 1.53rem + 2.6vw, 3.625rem);
  --text-display: clamp(2rem, 1.48rem + 2.2vw, 3.25rem);
}
html[lang="ja"] { --font-ui: "Inter", -apple-system, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", "Noto Sans JP", Meiryo, sans-serif; }
html[lang="ko"] { --font-ui: "Inter", -apple-system, "Apple SD Gothic Neo", Pretendard, "Noto Sans KR", "Malgun Gothic", sans-serif; }
html[lang="zh-Hant"] { --font-ui: "Inter", -apple-system, "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", sans-serif; }
html[lang="zh-Hans"] { --font-ui: "Inter", -apple-system, "PingFang SC", "Noto Sans SC", "Microsoft YaHei", sans-serif; }
html[lang="ja"] body, html[lang="ko"] body, html[lang^="zh"] body { line-break: strict; }

html[lang="ko"] body { word-break: keep-all; overflow-wrap: anywhere; }

@media (min-width: 641px) {
  html[lang="ja"] h1, html[lang="ja"] h2, html[lang="ja"] h3 { word-break: auto-phrase; overflow-wrap: anywhere; }
}

:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .hero__title { max-width: 12em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .hero__sub { max-width: 34em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .home .hero__sub { max-width: 26em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .head h2 { max-width: 14em; line-height: 1.3; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .endcta h2 { max-width: 13em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .stance { max-width: 20em; letter-spacing: 0; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .prose { max-width: 40em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .demo__step p { max-width: 23em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .pcard p { max-width: 24em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .figure__l { max-width: 15em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .figures__src { max-width: 37em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .disclose { max-width: 44em; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .facts dd { letter-spacing: 0; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) .nav__col--big a { max-width: none; letter-spacing: 0; line-height: 1.4; }
:is(html[lang="ja"], html[lang="ko"], html[lang^="zh"]) footer.foot .foot__tag { max-width: 17em; }

footer.foot .lang { margin-top: var(--space-6); }
footer.foot .lang ul { display: flex; flex-wrap: wrap; gap: 0 var(--space-2); margin: 0; padding: 0; list-style: none; }
footer.foot .lang li + li::before { content: "·"; margin-right: var(--space-2); color: var(--color-line-strong); }
footer.foot .lang a { display: inline-flex; align-items: center; min-height: 24px; font-size: 0.8125rem; line-height: 1.4; color: var(--color-fg-muted); }
footer.foot .lang a[aria-current] { color: var(--color-fg); }
footer.foot .lang a:hover { color: var(--color-fg); }
.lang-note a { text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 0.18em; text-decoration-color: var(--color-line-strong); }
.lang-note a:hover { text-decoration-color: currentColor; }

.nav__item--lang .nav__link { display: inline-flex; align-items: center; gap: 6px; }
.nav__globe { width: 15px; height: 15px; flex: none; fill: none; stroke: currentColor; stroke-width: 1.4; }
.nav__panel--lang .nav__col a[aria-current] { color: var(--color-fg); font-weight: var(--font-weight-semibold, 600); }
@media (min-width: 1001px) {
  .nav__panel--lang .nav__panel-inner { grid-template-columns: minmax(0, 260px); justify-content: end; }
}