/* OHLAC — shared design system + homepage.
   The token layer, brand wordmark, buttons and control primitives are shared
   with the generated /product and /legal pages (which also load legal.css). */

@font-face {
  font-family: "Inter Var";
  src: local("Inter Variable"), local("InterVariable"), local("Inter"),
       url("assets/fonts/inter-variable.woff2") format("woff2-variations"),
       url("assets/fonts/inter-variable.woff2") format("woff2");
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC,
                 U+0304, U+0308, U+0329, U+2000-206F, U+2074, U+20AC, U+2122, U+2191,
                 U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

/* ── Tokens ─────────────────────────────────────────────────────── */

:root,
[data-theme="dark"] {
  color-scheme: dark;
  --canvas: #070707;
  --surface: #0d0d0d;
  --surface-strong: #131313;
  --surface-soft: rgba(255, 255, 255, 0.03);
  --text: rgba(255, 255, 255, 0.94);
  --text-secondary: rgba(255, 255, 255, 0.78);
  --text-muted: rgba(255, 255, 255, 0.58);
  --text-faint: rgba(255, 255, 255, 0.47);
  --line: rgba(255, 255, 255, 0.1);
  --line-soft: rgba(255, 255, 255, 0.055);
  --accent: rgba(255, 255, 255, 0.92);
  --accent-ink: #080808;
  --live: #45b87a;
  --inverse: #f0efe9;
  --inverse-ink: #11120f;
  --header: rgba(7, 7, 7, 0.76);
  --grid: rgba(255, 255, 255, 0.5);
  --halo: rgba(255, 255, 255, 0.045);
  --brand-orbit: rgba(255, 255, 255, 0.09);
  --button-secondary: rgba(255, 255, 255, 0.04);
  --brand-letter: #f4f4f4;
  --brand-letter-stroke: rgba(255, 255, 255, 0.35);
}

[data-theme="light"] {
  color-scheme: light;
  --canvas: #f7f7f6;
  --surface: #efefee;
  --surface-strong: #e6e6e4;
  --surface-soft: rgba(0, 0, 0, 0.035);
  --text: rgba(0, 0, 0, 0.9);
  --text-secondary: rgba(0, 0, 0, 0.72);
  --text-muted: rgba(0, 0, 0, 0.52);
  --text-faint: rgba(0, 0, 0, 0.45);
  --line: rgba(0, 0, 0, 0.12);
  --line-soft: rgba(0, 0, 0, 0.07);
  --accent: rgba(16, 16, 16, 0.9);
  --accent-ink: #fafafa;
  --live: #1f7a4d;
  --inverse: #141414;
  --inverse-ink: #f6f6f6;
  --header: rgba(247, 247, 246, 0.82);
  --grid: rgba(0, 0, 0, 0.45);
  --halo: rgba(0, 0, 0, 0.04);
  --brand-orbit: rgba(0, 0, 0, 0.09);
  --button-secondary: rgba(0, 0, 0, 0.035);
  --brand-letter: #171717;
  --brand-letter-stroke: rgba(0, 0, 0, 0.28);
}

/* ── Base ───────────────────────────────────────────────────────── */

* { box-sizing: border-box; }

html {
  width: 100%;
  max-width: 100%;
  overflow-x: clip;
  scroll-behavior: smooth;
  scroll-padding-top: 98px;
  scrollbar-width: thin;
  scrollbar-color: var(--line) transparent;
}

body {
  position: relative;
  width: 100%;
  max-width: 100%;
  margin: 0;
  min-width: 0;
  overflow-x: clip;
  background: var(--canvas);
  color: var(--text);
  font-family: "Inter Var", Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI Variable Text", "Segoe UI", "PingFang SC", "HarmonyOS Sans SC", MiSans, "Source Han Sans SC", "Microsoft YaHei UI", "Microsoft YaHei", "Apple SD Gothic Neo", "Malgun Gothic", "Noto Sans KR", sans-serif;
  font-size: 16px;
  line-height: 1.5;
  font-feature-settings: "cv05" 1, "cv11" 1, "calt" 1;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body.menu-open { overflow: hidden; }

a { color: inherit; text-decoration: none; }
button { color: inherit; font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button:focus-visible, a:focus-visible { outline: 2px solid var(--text); outline-offset: 4px; }
::selection { background: color-mix(in srgb, var(--text) 16%, transparent); }

.sr-only {
  position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}
.svg-defs { position: absolute; width: 0; height: 0; overflow: hidden; }

.skip-link {
  position: fixed; z-index: 100; left: 16px; top: 12px;
  padding: 10px 14px; background: var(--text); color: var(--canvas);
  border-radius: 8px; transform: translateY(-180%); transition: transform 140ms ease;
}
.skip-link:focus { transform: translateY(0); }

/* ── Brand wordmark (shared with /product and /legal) ───────────── */

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 13px;
  font-weight: 750;
  letter-spacing: .16em;
  line-height: 1;
  white-space: nowrap;
}
.brand--adaptive {
  gap: 0;
  font-family: "Helvetica Neue", Arial, ui-sans-serif, system-ui, sans-serif;
  font-size: 14px;
  font-weight: 700;
}
.brand--adaptive:has(.brand-icon) { gap: 8px; }
.brand-icon {
  display: block; width: 18px; height: 18px; flex: none;
  border-radius: 4px; object-fit: cover;
}
.brand-wordmark {
  display: inline-flex; align-items: center; overflow: hidden;
  letter-spacing: .075em;
  transition: letter-spacing 420ms cubic-bezier(.2, .75, .2, 1);
}
.brand-wordmark__fold,
.brand-wordmark__suffix {
  display: inline-block; overflow: hidden; opacity: 1;
  transform: translateX(0); transform-origin: left center;
  transition: max-width 420ms cubic-bezier(.2, .75, .2, 1), opacity 220ms ease, transform 420ms cubic-bezier(.2, .75, .2, 1);
}
.brand-wordmark__fold { max-width: 3em; }
.brand-wordmark__suffix { max-width: 2.6em; }
.site-header.is-compact .brand-wordmark,
.legal-header.is-compact .brand-wordmark { letter-spacing: .025em; }
.site-header.is-compact .brand-wordmark__fold,
.site-header.is-compact .brand-wordmark__suffix,
.legal-header.is-compact .brand-wordmark__fold,
.legal-header.is-compact .brand-wordmark__suffix {
  max-width: 0; opacity: 0; transform: translateX(-.35em) scaleX(.76);
}
.oc-mark {
  display: block; width: 18px; height: 18px; flex: none;
  fill: none; stroke: currentColor; stroke-width: 7.5;
  stroke-linecap: butt; stroke-linejoin: round;
}

/* ── Controls (shared) ──────────────────────────────────────────── */

/* 韩语断行：按词换行，避免行内随意断开导致版面跳动 */
html[lang="ko"] { word-break: keep-all; }

.icon-button, .language-button, .menu-button {
  display: inline-grid; place-items: center;
  min-width: 36px; height: 36px; padding: 0; border: 0;
  background: transparent; border-radius: 8px; cursor: pointer;
  color: var(--text-muted);
  transition: color 140ms ease, background 140ms ease;
}
.icon-button:hover, .language-button:hover, .menu-button:hover { color: var(--text); background: var(--surface-soft); }
.icon-button svg {
  width: 16px; height: 16px; fill: none; stroke: currentColor;
  stroke-linecap: round; stroke-linejoin: round; stroke-width: 1.5;
  transition: transform 320ms ease;
}
/* 主题按钮：浅色显示太阳，深色切换为月亮（两个 icon 叠放同一格，按钮尺寸不变） */
#theme-toggle svg { grid-area: 1 / 1; transition: transform 320ms ease, opacity 200ms ease; }
#theme-toggle .icon-moon { opacity: 0; transform: rotate(-45deg) scale(.7); }
[data-theme="dark"] #theme-toggle .icon-sun { opacity: 0; transform: rotate(45deg) scale(.7); }
[data-theme="dark"] #theme-toggle .icon-moon { opacity: 1; transform: none; }
.language-button { font-size: 12px; font-weight: 650; }

/* 语言按钮固定宽度：切换语言时头部控件与导航不随标签长短伸缩 */
.lang-switch .language-button {
  min-width: 54px; width: 54px; padding: 0;
  white-space: nowrap; text-align: center;
}

.lang-switch { position: relative; display: inline-flex; }
.lang-menu {
  position: absolute; top: calc(100% + 8px); right: 0; z-index: 40;
  min-width: 176px; margin: 0; padding: 6px; list-style: none;
  border: 1px solid var(--line); border-radius: 10px;
  background: var(--canvas);
  box-shadow: 0 14px 34px rgba(0, 0, 0, .16);
}
.lang-menu[hidden] { display: none; }
.lang-menu__option {
  display: block; width: 100%; padding: 8px 10px;
  border: 0; border-radius: 7px; background: transparent;
  color: var(--text-secondary); cursor: pointer;
  font: inherit; font-size: 13px; line-height: 1.5; text-align: left;
}
.lang-menu__option:hover { background: var(--surface-soft); color: var(--text); }
.lang-menu__option[aria-selected="true"] { color: var(--text); font-weight: 650; }

.button {
  min-height: 50px;
  display: inline-flex; align-items: center; justify-content: center; gap: 14px;
  padding: 0 20px;
  border: 1px solid var(--line);
  border-radius: 9px;
  font-size: 14px;
  font-weight: 720;
  transition: transform 220ms cubic-bezier(.2, .7, .2, 1), background 220ms cubic-bezier(.2, .7, .2, 1), border-color 220ms cubic-bezier(.2, .7, .2, 1);
}
.button:hover { transform: translateY(-1px); }
.button:active { transform: translateY(1px) scale(.985); transition-duration: 80ms; }
.button > span[aria-hidden] { display: inline-block; transition: transform 260ms cubic-bezier(.2, .7, .2, 1); }
.button:hover > span[aria-hidden] { transform: translateX(3px); }
.button--primary { border-color: var(--accent); background: var(--accent); color: var(--accent-ink); }
.button--primary:hover { border-color: var(--text); background: var(--text); }
.button--secondary { background: var(--button-secondary); color: var(--text-secondary); }
.button--secondary:hover { border-color: var(--text-muted); color: var(--text); }

/* ── Background ─────────────────────────────────────────────────── */

.site-bg {
  position: fixed; z-index: -1; inset: 0;
  width: 100%; max-width: 100vw;
  contain: strict; overflow: hidden; pointer-events: none;
  background:
    radial-gradient(circle 46vw at calc(100% + 8vw) -16vh, var(--halo), transparent 68%),
    radial-gradient(circle 40vw at -12vw calc(100% + 18vh), var(--halo), transparent 72%),
    var(--canvas);
}
.site-grid {
  position: absolute; inset: 0; opacity: .022;
  background-image:
    repeating-radial-gradient(circle at 17% 23%, var(--grid) 0 .45px, transparent .55px 3.8px),
    repeating-radial-gradient(circle at 78% 61%, var(--grid) 0 .35px, transparent .55px 5.2px);
  background-size: 142px 142px, 210px 210px;
}
[data-theme="light"] .site-grid { opacity: .03; }
/* 一种极浅的环形线与 Flowing Link 破口标，作为品牌背景语言，始终低于正文层级。 */
.site-bg::after {
  content: "";
  position: absolute;
  right: -14%; top: -7%;
  width: min(64vw, 900px); aspect-ratio: 1;
  border: 1px solid var(--line-soft);
  border-radius: 50%;
  opacity: .6;
}
.brand-orbit {
  position: absolute;
  right: clamp(-60px, 3vw, 60px);
  top: clamp(96px, 16vh, 172px);
  width: clamp(340px, 38vw, 600px);
  aspect-ratio: 240 / 140;
  transform: rotate(-6deg);
  opacity: .5;
}
.brand-orbit svg { width: 100%; height: 100%; overflow: visible; }
.brand-orbit path {
  fill: none;
  stroke: var(--brand-orbit);
  stroke-width: clamp(16px, 2vw, 27px);
  stroke-linecap: butt;
  stroke-linejoin: round;
}
[data-theme="dark"] .brand-orbit { opacity: .62; }

/* ── Header ─────────────────────────────────────────────────────── */

.site-header {
  position: sticky; top: 0; z-index: 30;
  border-bottom: 1px solid transparent;
  background: linear-gradient(to bottom, var(--header) 0%, color-mix(in srgb, var(--header) 72%, transparent) 70%, transparent 100%);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: border-color 200ms ease;
}
.site-header.is-compact { border-bottom-color: var(--line-soft); }
.site-header__inner {
  width: min(1200px, calc(100% - 48px));
  height: 78px; margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between; gap: 24px;
}
.desktop-nav {
  display: flex; align-items: center; gap: clamp(14px, 2vw, 28px);
  margin-left: auto; margin-right: 16px;
}
.desktop-nav a {
  padding: 5px 0;
  color: var(--text-muted); font-size: 13px;
  transition: color 140ms ease;
}
.desktop-nav a:hover { color: var(--text); }
/* 语言切换稳定性：导航与 CTA 不换行、控件区不压缩，切换语言时头部高度与宽度不变 */
.desktop-nav { flex-wrap: nowrap; min-width: 0; }
.desktop-nav a, .mobile-menu a, .header-cta { white-space: nowrap; }
.site-header__actions { display: flex; align-items: center; flex: 0 0 auto; gap: 6px; }
.header-cta {
  display: inline-flex; min-height: 36px; align-items: center;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-soft);
  color: var(--text);
  font-size: 12px; font-weight: 650;
  transition: background 180ms ease, border-color 180ms ease, color 180ms ease, transform 180ms ease;
}
.header-cta:hover { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); transform: translateY(-1px); }
.menu-button { display: none; position: relative; gap: 4px; }
.menu-button span { position: absolute; display: block; width: 15px; height: 1px; background: currentColor; transition: transform 220ms ease; }
.menu-button span:first-child { transform: translateY(-3px); }
.menu-button span:last-child { transform: translateY(3px); }
.menu-button[aria-expanded="true"] span:first-child { transform: rotate(45deg); }
.menu-button[aria-expanded="true"] span:last-child { transform: rotate(-45deg); }

.scroll-progress { position: absolute; left: 0; right: 0; bottom: 0; height: 1px; pointer-events: none; }
.scroll-progress i {
  display: block; height: 100%; width: 100%;
  transform: scaleX(0); transform-origin: left center;
  background: var(--text); opacity: .3;
  transition: transform 110ms linear;
}

.mobile-menu {
  width: min(100%, 760px); margin: 0 auto;
  padding: 8px 24px 20px;
  border-top: 1px solid var(--line-soft);
  background: var(--canvas);
}
.mobile-menu:not([hidden]) { animation: enter 200ms ease both; max-height: calc(100dvh - 68px); overflow-y: auto; }
.mobile-menu a {
  display: block; padding: 13px 0;
  border-bottom: 1px solid var(--line-soft);
  color: var(--text-secondary);
}
.mobile-menu .mobile-menu__cta {
  margin-top: 12px; padding: 12px 14px;
  border: 1px solid var(--line); border-radius: 10px;
  color: var(--text); font-weight: 650;
}

/* ── Layout primitives ──────────────────────────────────────────── */

.hero, .section, .final-cta, .site-footer { width: min(1200px, calc(100% - 48px)); margin: 0 auto; }

h1, h2, h3, p { margin-top: 0; }
h1 {
  max-width: 15em; margin-bottom: 20px;
  font-size: clamp(34px, 4.4vw, 52px);
  font-weight: 600; letter-spacing: -.045em; line-height: 1.12;
  text-wrap: balance;
}
h2 {
  margin-bottom: 16px;
  font-size: clamp(27px, 3.1vw, 40px);
  font-weight: 600; letter-spacing: -.04em; line-height: 1.15;
  text-wrap: balance;
}
h3 { font-size: 20px; font-weight: 600; letter-spacing: -.03em; line-height: 1.25; }

.eyebrow {
  display: flex; align-items: center; gap: 8px; margin: 0 0 14px;
  color: var(--text-secondary);
  font-size: 13px; font-weight: 600; letter-spacing: .04em;
}
.status-dot {
  display: inline-block; width: 6px; height: 6px; border-radius: 50%;
  background: var(--live);
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--live) 18%, transparent);
}

.section { padding: clamp(56px, 7vw, 96px) 0 0; }
.section-head { max-width: 46rem; margin-bottom: 36px; }
.section-head h2 { max-width: 22em; }
.section-lead {
  max-width: 42rem; margin: 0;
  color: var(--text-secondary);
  font-size: clamp(15px, 1.5vw, 17px); line-height: 1.75;
  text-wrap: pretty;
}
.section-foot { display: flex; flex-wrap: wrap; align-items: center; gap: 16px 20px; margin-top: 32px; }
.section-note { margin: 0; color: var(--text-faint); font-size: 13px; line-height: 1.6; }
.section-note--wide { margin-top: 20px; max-width: 42rem; }

.text-link {
  position: relative; display: inline-flex; align-items: center; gap: 10px;
  color: var(--text); font-size: 13px; font-weight: 680;
  transition: color 200ms cubic-bezier(.2, .7, .2, 1);
}
.text-link::after {
  content: ""; position: absolute; left: 0; right: 100%; bottom: -3px; height: 1px;
  background: currentColor; opacity: .5;
  transition: right 320ms cubic-bezier(.2, .7, .2, 1);
}
.text-link:hover::after { right: 0; }
.text-link > span[aria-hidden] { display: inline-block; transition: transform 280ms cubic-bezier(.2, .7, .2, 1); }
.text-link:hover > span[aria-hidden] { transform: translateX(4px); }
.text-link--muted { color: var(--text-muted); font-weight: 560; }
.text-link--muted:hover { color: var(--text); }

/* ── Hero ───────────────────────────────────────────────────────── */

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.06fr);
  align-items: center;
  gap: clamp(32px, 5vw, 68px);
  padding: clamp(40px, 5vw, 72px) 0 clamp(28px, 4vw, 48px);
}
.hero__copy { max-width: 34rem; }
.hero__actions { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; margin-top: 30px; }
.hero__note { margin: 16px 0 0; color: var(--text-faint); font-size: 13px; }
.hero__note a { color: var(--text-muted); text-decoration: underline; text-underline-offset: 3px; }
.hero__note a:hover { color: var(--text); }

.hero-preview {
  position: relative;
  width: 100%; justify-self: stretch;
  border: 1px solid var(--line);
  border-radius: 16px;
  overflow: hidden;
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  box-shadow: 0 24px 60px rgba(0, 0, 0, .14);
}
[data-theme="dark"] .hero-preview { box-shadow: 0 24px 70px rgba(0, 0, 0, .42); }
.hero-preview__bar {
  display: flex; align-items: center; gap: 12px;
  height: 48px; padding: 0 16px;
  border-bottom: 1px solid var(--line-soft);
  background: var(--surface-soft);
}
.traffic-lights { display: inline-flex; flex: none; align-items: center; gap: 6px; }
.traffic-light { display: block; width: 9px; height: 9px; border-radius: 50%; }
.traffic-light--close { background: #ff5f57; }
.traffic-light--minimize { background: #febc2e; }
.traffic-light--zoom { background: #28c840; }
.hero-preview__title { font-size: 12px; font-weight: 650; color: var(--text-secondary); }
.preview-live {
  display: inline-flex; align-items: center; gap: 6px; margin-left: auto;
  border: 1px solid color-mix(in srgb, var(--live) 26%, var(--line));
  border-radius: 99px; padding: 3px 9px;
  color: var(--live); font-size: 10px; font-weight: 700; letter-spacing: .04em; white-space: nowrap;
}
.preview-live i { width: 5px; height: 5px; border-radius: 50%; background: var(--live); }

.hero-preview__models { padding: 12px 16px; border-bottom: 1px solid var(--line-soft); }
.hero-preview__models-label {
  margin: 0 0 8px; color: var(--text-faint);
  font-size: 10px; font-weight: 700; letter-spacing: .1em; text-transform: uppercase;
}
.model-chips { display: flex; gap: 6px; overflow-x: auto; padding-bottom: 2px; scrollbar-width: none; }
.model-chips::-webkit-scrollbar { display: none; }
.model-chip {
  flex: 0 0 auto;
  display: inline-flex; align-items: center; gap: 7px;
  min-height: 32px; padding: 0 11px 0 8px;
  border: 1px solid transparent; border-radius: 7px;
  background: transparent; color: var(--text-muted);
  font-size: 11.5px; font-weight: 620; white-space: nowrap; cursor: pointer;
  transition: background 180ms ease, border-color 180ms ease, color 180ms ease;
}
.model-chip:hover { border-color: var(--line); background: var(--surface-soft); color: var(--text); }
.model-chip.is-selected {
  border-color: color-mix(in srgb, var(--text) 26%, var(--line));
  background: var(--surface-soft); color: var(--text);
}
.model-chip:focus-visible { outline-offset: -2px; }
.model-mark {
  display: grid; place-items: center;
  width: 16px; height: 16px; flex: none;
  color: var(--text-secondary);
}
.model-mark img { width: 16px; height: 16px; border-radius: 3px; object-fit: contain; }
.model-mark svg { width: 15px; height: 15px; }
/* 品牌 Icon 保留有限色彩：OpenAI / xAI 本身为单色标，按主题反相；
   Anthropic 与 Google 使用官方品牌色，图片类图标带一层细描边以适配深浅主题。 */
.model-chip[data-model="OpenAI"] .model-mark,
.model-chip[data-model="Grok"] .model-mark { color: #0d0d0d; }
[data-theme="dark"] .model-chip[data-model="OpenAI"] .model-mark,
[data-theme="dark"] .model-chip[data-model="Grok"] .model-mark { color: #f5f5f5; }
.model-chip[data-model="Claude"] .model-mark { color: #d97757; }
.model-mark--tile img { border: 1px solid var(--line); border-radius: 4px; }

.hero-preview__body { display: grid; gap: 16px; padding: 20px 16px; min-height: 190px; align-content: start; }
.hero-preview__user {
  justify-self: end; max-width: 84%; margin: 0;
  padding: 10px 13px;
  border: 1px solid var(--line); border-radius: 12px 12px 3px 12px;
  background: var(--surface-soft);
  color: var(--text-secondary); font-size: 13px; line-height: 1.55;
}
.hero-preview__answer-label {
  margin: 0 0 6px; color: var(--text-faint);
  font-size: 9.5px; font-weight: 760; letter-spacing: .09em; text-transform: uppercase;
}
.hero-preview__answer-text { margin: 0; color: var(--text); font-size: 13.5px; line-height: 1.7; }
.hero-preview__composer {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  margin: 0 16px 16px; padding: 8px 8px 8px 13px;
  border: 1px solid var(--line); border-radius: 11px;
  background: var(--surface-soft);
  color: var(--text-faint); font-size: 12px;
}
.hero-preview__send {
  display: grid; place-items: center;
  width: 32px; height: 32px; flex: none;
  border-radius: 6px; background: var(--text); color: var(--canvas);
  font-weight: 800; font-size: 13px;
}

/* ── Brand annotation (restored backronym) ──────────────────────── */

/* 品牌注解：位于 Hero 主标题之下，沿用旧版「先亮字母、再展开词缀」的循环表现。 */
.brand-note {
  width: 100%;
  min-height: 92px;
  margin: 4px 0 22px;
  padding-top: 16px;
  border-top: 1px solid var(--line-soft);
}
.brand-note__backronym {
  position: relative;
  margin: 0;
  color: var(--text-secondary);
  font-size: clamp(15px, 1.45vw, 18px);
  font-weight: 540;
  letter-spacing: -.018em;
  line-height: 1.45;
  transition:
    font-size 520ms cubic-bezier(.2, .7, .2, 1),
    letter-spacing 520ms cubic-bezier(.2, .7, .2, 1),
    opacity 420ms ease,
    transform 420ms cubic-bezier(.2, .7, .2, 1);
}
.brand-note.is-letters:not(.is-expanded) .brand-note__backronym {
  font-size: clamp(26px, 3.6vw, 40px);
  font-weight: 520;
  letter-spacing: .2em;
  line-height: 1.14;
}
.brand-note__word { display: inline-flex; align-items: baseline; white-space: nowrap; }
.brand-note__word + .brand-note__word { margin-left: .28em; }
.brand-note.is-letters:not(.is-expanded) .brand-note__word + .brand-note__word { margin-left: .14em; }
.brand-note__word--muted {
  max-width: 0; margin-left: 0 !important; opacity: 0; overflow: hidden;
  transform: translateY(.12em);
  transition:
    max-width 620ms cubic-bezier(.2, .7, .2, 1),
    opacity 480ms ease,
    margin 520ms cubic-bezier(.2, .7, .2, 1),
    transform 620ms cubic-bezier(.2, .7, .2, 1);
}
.brand-note.is-expanded .brand-note__word--muted {
  max-width: 3em; margin-left: .28em !important; opacity: .72; transform: none;
}
.brand-note__backronym .initial {
  display: inline-block;
  color: var(--brand-letter);
  font-family: "Avenir Next", Avenir, "Segoe UI", Candara, "Century Gothic", sans-serif;
  font-weight: 600;
  font-size: 1.05em;
  letter-spacing: .02em;
  line-height: 1;
  -webkit-text-stroke: 0.6px var(--brand-letter-stroke);
  paint-order: stroke fill;
  opacity: 0;
  transform: translateY(.14em);
  transition: opacity 480ms cubic-bezier(.2, .7, .2, 1), transform 560ms cubic-bezier(.2, .7, .2, 1);
  transition-delay: calc(var(--i, 0) * 70ms);
}
.brand-note.is-letters .initial { opacity: 1; transform: none; }
.brand-note.is-letters:not(.is-expanded) .initial {
  font-weight: 650; letter-spacing: .05em; -webkit-text-stroke-width: 0.85px;
}
.brand-note__backronym .rest {
  display: inline-block;
  max-width: 0; opacity: 0; overflow: hidden;
  transform: translateX(-.18em);
  filter: blur(2px);
  vertical-align: baseline;
  transition:
    max-width 720ms cubic-bezier(.2, .7, .2, 1),
    opacity 520ms ease,
    transform 720ms cubic-bezier(.2, .7, .2, 1),
    filter 720ms cubic-bezier(.2, .7, .2, 1);
  transition-delay: calc(var(--i, 0) * 40ms);
}
.brand-note.is-expanded .rest { max-width: 12em; opacity: 1; transform: none; filter: none; }
.brand-note__copy {
  margin: 8px 0 0;
  color: var(--text-muted);
  font-size: 14px; line-height: 1.55;
  transition: opacity 700ms ease, transform 700ms cubic-bezier(.2, .7, .2, 1);
  transition-delay: 80ms;
}
/* 无 JS 时中文释义保持可见，只有脚本就绪后才做淡入。 */
html.js .brand-note__copy { opacity: 0; transform: translateY(7px); }
.brand-note.is-revealed .brand-note__copy { opacity: 1; transform: none; }
.brand-note.is-exiting .brand-note__backronym,
.brand-note.is-exiting .brand-note__copy {
  opacity: 0; transform: translateY(-6px); transition-delay: 0ms;
}

/* ── Capabilities ───────────────────────────────────────────────── */

.capability-grid {
  display: grid; grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0;
  border-top: 1px solid var(--line);
}
.capability {
  padding: 34px 0 6px;
}
.capability + .capability { padding-left: clamp(24px, 4vw, 56px); border-left: 1px solid var(--line); }
.capability:first-child { padding-right: clamp(24px, 4vw, 56px); }
.capability__head { margin-bottom: 14px; }
.capability__label {
  display: inline-block; margin-bottom: 12px;
  color: var(--text-faint);
  font-size: 11px; font-weight: 700; letter-spacing: .12em; text-transform: uppercase;
}
.capability__head h3 { max-width: 18em; margin-bottom: 0; font-size: clamp(21px, 2.3vw, 27px); }
.capability__desc { max-width: 30rem; margin: 0 0 20px; color: var(--text-secondary); font-size: 15px; line-height: 1.75; text-wrap: pretty; }
.capability__list { display: grid; gap: 11px; margin: 0 0 26px; padding: 0; list-style: none; }
.capability__list li {
  position: relative; padding-left: 18px;
  color: var(--text-secondary); font-size: 14.5px; line-height: 1.65;
}
.capability__list li::before {
  content: ""; position: absolute; left: 0; top: .68em;
  width: 6px; height: 1px; background: var(--text-faint);
}
.capability__actions { display: flex; flex-wrap: wrap; align-items: center; gap: 20px; }

/* ── Model families ─────────────────────────────────────────────── */

.family-grid {
  display: grid; grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0; margin: 0; padding: 0; list-style: none;
  border-top: 1px solid var(--line); border-bottom: 1px solid var(--line);
}
.family { padding: 24px 24px 26px; border-left: 1px solid var(--line-soft); }
.family:nth-child(3n + 1) { border-left: 0; padding-left: 0; }
.family:nth-child(3n) { padding-right: 0; }
.family:nth-child(n + 4) { border-top: 1px solid var(--line-soft); }
.family__head { display: flex; align-items: center; gap: 9px; margin-bottom: 8px; }
.family__icon { display: grid; place-items: center; width: 18px; height: 18px; flex: none; color: var(--text-secondary); }
.family__icon svg { width: 100%; height: 100%; }
.family__icon--mono { color: #0d0d0d; }
[data-theme="dark"] .family__icon--mono { color: #f2f2f2; }
.family__icon--tile img { width: 100%; height: 100%; border: 1px solid var(--line); border-radius: 4px; object-fit: contain; }
.family__name { font-size: 16px; font-weight: 650; letter-spacing: -.01em; }
.family__tag { display: block; margin-bottom: 12px; color: var(--text-faint); font-size: 11.5px; letter-spacing: .02em; }
.family__models {
  margin: 0 0 12px;
  color: var(--text-muted);
  font-size: 11.5px; line-height: 1.6;
  font-feature-settings: "tnum";
}
.family__desc { margin: 0; color: var(--text-secondary); font-size: 13px; line-height: 1.7; }

/* ── Image use cases ────────────────────────────────────────────── */

.gallery { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 14px; }
.gallery__item { margin: 0; }
.gallery__frame {
  display: grid; place-items: center;
  aspect-ratio: 1 / 1; margin-bottom: 12px;
  border: 1px solid var(--line); border-radius: 12px;
  background: linear-gradient(160deg, var(--surface-soft), transparent 70%), var(--surface);
  overflow: hidden;
}
.gallery__frame svg {
  width: 62%; height: 62%;
  fill: none; stroke: var(--text-muted); stroke-width: 3;
  stroke-linecap: round; stroke-linejoin: round; opacity: .78;
}
.gallery__item figcaption { display: grid; gap: 4px; }
.gallery__title { color: var(--text); font-size: 13.5px; font-weight: 620; }
.gallery__desc { color: var(--text-muted); font-size: 12.5px; line-height: 1.6; }

/* ── How it works ───────────────────────────────────────────────── */

.steps {
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0; margin: 0; padding: 0; list-style: none;
  border-top: 1px solid var(--line); border-bottom: 1px solid var(--line);
}
.step { padding: 26px 22px 28px; border-left: 1px solid var(--line-soft); }
.step:first-child { border-left: 0; padding-left: 0; }
.step:last-child { padding-right: 0; }
.step__index {
  display: block; margin-bottom: 16px;
  color: var(--text-faint);
  font-size: 12px; font-variant-numeric: tabular-nums;
}
.step h3 { margin-bottom: 8px; font-size: 17px; }
.step p { margin: 0; color: var(--text-secondary); font-size: 13.5px; line-height: 1.7; }

/* ── Credits / facts ────────────────────────────────────────────── */

.facts {
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line);
}
.fact { padding: 22px 22px 24px; border-left: 1px solid var(--line-soft); }
.fact:first-child { border-left: 0; padding-left: 0; }
.fact:last-child { padding-right: 0; }
.fact__label {
  display: block; margin-bottom: 10px;
  color: var(--text-faint);
  font-size: 10.5px; font-weight: 700; letter-spacing: .1em; text-transform: uppercase;
}
.fact__value { margin: 0; color: var(--text-secondary); font-size: 13.5px; line-height: 1.7; }

/* ── Guides ─────────────────────────────────────────────────────── */

.guide-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.guide-card {
  display: grid; align-content: start; gap: 10px;
  padding: 24px 24px 22px;
  border: 1px solid var(--line); border-radius: 14px;
  background: color-mix(in srgb, var(--surface) 55%, transparent);
  transition: border-color 180ms ease, background 180ms ease, transform 180ms ease;
}
.guide-card:hover {
  border-color: color-mix(in srgb, var(--text) 22%, var(--line));
  background: var(--surface);
  transform: translateY(-2px);
}
.guide-card__topic {
  color: var(--text-faint);
  font-size: 10.5px; font-weight: 700; letter-spacing: .1em; text-transform: uppercase;
}
.guide-card h3 { margin: 0; font-size: 19px; letter-spacing: -.03em; }
.guide-card p { margin: 0; color: var(--text-secondary); font-size: 14px; line-height: 1.7; text-wrap: pretty; }
.guide-card__meta { margin-top: 4px; color: var(--text-faint); font-size: 12px; }

/* ── FAQ ────────────────────────────────────────────────────────── */

.faq { border-top: 1px solid var(--line); max-width: 52rem; }
.faq__item { border-bottom: 1px solid var(--line-soft); }
.faq__item summary {
  position: relative;
  padding: 20px 40px 20px 0;
  color: var(--text); font-size: 16px; font-weight: 570; letter-spacing: -.01em;
  cursor: pointer; list-style: none;
}
.faq__item summary::-webkit-details-marker { display: none; }
.faq__item summary::after {
  content: "+"; position: absolute; right: 4px; top: 50%;
  transform: translateY(-50%);
  color: var(--text-faint); font-size: 18px; font-weight: 400;
  transition: transform 200ms ease, color 200ms ease;
}
.faq__item summary:hover { color: var(--text); }
.faq__item summary:hover::after { color: var(--text); }
.faq__item[open] summary::after { content: "−"; }
.faq__item p {
  margin: 0; padding: 0 40px 22px 0;
  color: var(--text-secondary); font-size: 14.5px; line-height: 1.78;
  text-wrap: pretty;
}
.faq__item p a { color: var(--text); text-decoration: underline; text-underline-offset: 3px; text-decoration-color: color-mix(in srgb, var(--text) 30%, transparent); }
.faq__item p a:hover { text-decoration-color: var(--text); }

/* ── Final CTA + footer ─────────────────────────────────────────── */

.final-cta {
  display: flex; align-items: end; justify-content: space-between;
  gap: 36px; margin-top: clamp(64px, 8vw, 104px);
  padding: clamp(34px, 5vw, 56px) 0;
  border-top: 1px solid var(--line);
}
.final-cta h2 { margin-bottom: 8px; font-size: clamp(27px, 3.1vw, 40px); }
.final-cta .eyebrow { color: var(--text-muted); }
.final-cta p:not(.eyebrow) { margin-bottom: 0; max-width: 34rem; color: var(--text-secondary); font-size: 15px; line-height: 1.7; }
.final-cta__actions { flex: none; display: flex; flex-wrap: wrap; gap: 12px; }

.site-footer {
  display: grid;
  grid-template-columns: minmax(180px, 1.1fr) minmax(430px, 1.6fr);
  gap: 40px;
  padding: 54px 0 46px;
  border-top: 1px solid var(--line);
  content-visibility: auto;
  contain-intrinsic-size: auto 280px;
}
.site-footer__identity > p { max-width: 220px; margin: 17px 0 0; color: var(--text-muted); font-size: 13px; line-height: 1.6; }
.site-footer__links { display: grid; grid-template-columns: repeat(4, minmax(110px, 1fr)); gap: 24px; }
.site-footer__links > div { display: grid; align-content: start; gap: 8px; }
.site-footer__links > div > span { color: var(--text-faint); font-size: 10px; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; }
.site-footer__links a, .site-footer__links p { margin: 0; color: var(--text-secondary); font-size: 12px; }
.site-footer__links a:hover { color: var(--text); }
.site-footer__links p { display: inline-flex; align-items: center; gap: 7px; }
.site-footer__links small { margin-top: 5px; color: var(--text-faint); font-size: 11px; }
.footer-live-dot { width: 5px; height: 5px; border-radius: 50%; background: var(--live); }
.site-footer__copyright { grid-column: 1 / -1; margin: 6px 0 0; color: var(--text-faint); font-size: 12px; }

/* ── Reveal motion ──────────────────────────────────────────────── */

.js .reveal { opacity: 0; transform: translateY(16px); transition: opacity .62s cubic-bezier(.2, .7, .2, 1), transform .62s cubic-bezier(.2, .7, .2, 1); }
.js .reveal.is-visible { opacity: 1; transform: none; }
.js .reveal--delayed { transition-delay: .1s; }

@keyframes enter { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }

/* ── Guide pages (docs chrome, /guides) ─────────────────────────── */

.guide-related { display: grid; gap: 12px; margin-top: 2.6rem; padding-top: 1.6rem; border-top: 1px solid var(--line-soft); }
.guide-related__label { margin: 0; color: var(--text-faint); font-size: 11px; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; }
.guide-related__links { display: flex; flex-wrap: wrap; gap: 10px; }
.guide-related__links a {
  padding: 8px 14px;
  border: 1px solid var(--line); border-radius: 999px;
  color: var(--text-secondary); font-size: 13px;
  transition: border-color 160ms ease, color 160ms ease, background 160ms ease;
}
.guide-related__links a:hover { border-color: var(--text-muted); color: var(--text); background: var(--surface-soft); }

/* ── Responsive ─────────────────────────────────────────────────── */

@media (max-width: 1100px) {
  .hero { grid-template-columns: minmax(0, .95fr) minmax(0, 1.05fr); gap: 36px; }
  .family-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .family { padding: 24px; border-left: 1px solid var(--line-soft); border-top: 0; }
  .family:nth-child(3n), .family:nth-child(3n + 1) { padding-left: 24px; padding-right: 24px; }
  .family:nth-child(2n + 1) { border-left: 0; padding-left: 0; }
  .family:nth-child(2n) { padding-right: 0; }
  .family:nth-child(n + 3) { border-top: 1px solid var(--line-soft); }
  .gallery { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .steps, .facts { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .step:nth-child(2n), .fact:nth-child(2n) { padding-right: 0; }
  .step:nth-child(2n + 1), .fact:nth-child(2n + 1) { padding-left: 0; border-left: 0; }
  .step:nth-child(n + 3), .fact:nth-child(n + 3) { border-top: 1px solid var(--line-soft); }
}

@media (max-width: 860px) {
  .hero, .section, .final-cta, .site-footer, .site-header__inner { width: min(calc(100% - 40px), 680px); }
  .desktop-nav, .header-cta { display: none; }
  .site-header__inner { height: 68px; }
  .menu-button { display: grid; }

  .hero { grid-template-columns: 1fr; gap: 36px; padding-top: 44px; }
  .hero__copy { max-width: none; }
  .hero-preview { order: 2; }
  .hero-preview__body { min-height: 0; }

  .capability-grid { grid-template-columns: 1fr; border-top: 1px solid var(--line); }
  .capability { padding: 28px 0; }
  .capability:first-child { padding-right: 0; border-bottom: 1px solid var(--line); }
  .capability + .capability { padding-left: 0; border-left: 0; }
  .guide-grid { grid-template-columns: 1fr; }
  .final-cta { flex-direction: column; align-items: flex-start; }
  .site-footer { grid-template-columns: 1fr; gap: 34px; }
  .site-footer__links { grid-template-columns: repeat(2, minmax(120px, 1fr)); }
}

@media (max-width: 560px) {
  .family-grid { grid-template-columns: 1fr; }
  .family { padding: 22px 0; border-left: 0 !important; }
  .family + .family { border-top: 1px solid var(--line-soft); }
  .gallery { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
  .steps, .facts { grid-template-columns: 1fr; }
  .step, .fact { padding: 22px 0; border-left: 0 !important; }
  .step + .step, .fact + .fact { border-top: 1px solid var(--line-soft); }
  .hero__actions, .final-cta__actions { width: 100%; align-items: stretch; }
  .button { width: 100%; }
  .site-footer__links { grid-template-columns: 1fr 1fr; }
  /* mobile：品牌注解收紧字号与字距，避免字母展开时拥挤。 */
  .brand-orbit { opacity: .26; width: 300px; right: -58px; top: 132px; }
  .brand-note { padding-top: 18px; }
  .brand-note { min-height: 84px; }
  .brand-note.is-letters:not(.is-expanded) .brand-note__backronym { font-size: clamp(22px, 7vw, 30px); letter-spacing: .12em; }
  .brand-note__copy { font-size: 13px; }
}

@media (max-width: 520px) {
  .hero, .section, .final-cta, .site-footer, .site-header__inner { width: calc(100% - 32px); }
  .site-header__actions { gap: 2px; }
  .icon-button, .language-button, .menu-button { min-width: 44px; height: 44px; }
  .hero { padding-top: 36px; }
  .hero-preview { border-radius: 14px; }
  .gallery { grid-template-columns: 1fr 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
  .js .reveal { opacity: 1; transform: none; }
  button, a, .button, .guide-card, .icon-button svg { transition: none; }
  .button:hover, .button:active, .guide-card:hover, .header-cta:hover { transform: none; }
}