:root {
  --bg: #ffffff;
  --bg-panel: #f0f3f6;
  --bg-panel-2: #f7f9fa;
  --border: #dde2e7;
  --accent: #0e86c2;
  --accent-dark: #0a6496;
  --text: #2c3237;
  --text-muted: #69737b;
  --success: #2e9e6a;
  --warn: #c98a12;
  --error: #d1453b;
  --hairline: #e7ebef;
  --device-line: #d5dbe1;
  --grid-line: #e9edf1;
  --chevron: #b8c0c7;
  --on-accent: #ffffff;
  --mask-solid: #000000;
  --clear: transparent;
  --accent-soft: rgba(14, 134, 194, .16);
  --floor-shadow: rgba(40, 56, 72, .13);
  --veil: rgba(44, 50, 55, .24);

  --font-display: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans", "Apple SD Gothic Neo", "Microsoft YaHei", sans-serif;
  --font-body: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans", "Apple SD Gothic Neo", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --fs-h1: clamp(34px, 2.4vw + 14px, 48px);
  --fs-h2: clamp(24px, 2.5vw, 34px);
  --fs-h3: 21px;
  --fs-body: 16px;
  --fs-small: 14px;
  --weight-normal: 400;
  --weight-medium: 500;
  --weight-bold: 700;
  --weight-heavy: 800;
  --tracking-title: -.02em;
  --tracking-latin: -.03em;

  --r-card: 8px;
  --r-btn: 6px;
  --r-pill: 999px;
  --r-circle: 50%;
  --r-screen: 6px;
  --r-shot: 10px;
  --r-ipad: 26px;
  --r-iphone: 32px;
  --r-iphone-screen: 24px;
  --r-mark: 7px;
  --r-tab: 4px 0 0 4px;
  --r-hardware: 2px;

  --shadow-soft: 0 1px 2px rgba(36, 52, 68, .04), 0 10px 28px -18px rgba(36, 52, 68, .16);
  --shadow-btn: inset 0 1px 0 rgba(255, 255, 255, .18), 0 8px 18px -10px rgba(14, 134, 194, .6);
  --shadow-icon: 0 0 0 1px var(--border), 0 6px 12px -8px rgba(36, 52, 68, .3);
  --shadow-ipad: 0 1px 2px rgba(36, 52, 68, .04), 0 18px 40px -22px rgba(36, 52, 68, .16), 0 46px 90px -36px rgba(36, 52, 68, .18);
  --shadow-iphone: 0 2px 4px rgba(36, 52, 68, .06), 0 22px 44px -18px rgba(36, 52, 68, .26), 0 56px 100px -34px rgba(36, 52, 68, .3);

  --gutter: 24px;
  --width-content: 1120px;
  --width-reading: 760px;
  --width-header: 1280px;
  --header-h: 64px;
  --section-space: 160px;
  --space-card: 28px;
  --space-grid: 24px;
  --duration-fast: .2s;
  --duration-reveal: .6s;
  --ease: ease;
  --z-header: 40;
  --z-veil: 30;
  --z-fab: 20;
  --z-skip: 60;
}

*, *::before, *::after { box-sizing: border-box; }
html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 24px);
}
html.nav-open { overflow: hidden; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: clip;
}
img, svg { max-width: 100%; vertical-align: middle; }
img { height: auto; }
button, input, select, textarea { font: inherit; }
button { cursor: pointer; }
button, a { -webkit-tap-highlight-color: var(--clear); }
a { color: var(--accent-dark); text-underline-offset: .2em; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible {
  outline: 2px solid var(--accent-dark);
  outline-offset: 3px;
  border-radius: var(--r-btn);
}
[hidden] { display: none !important; }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: var(--weight-heavy);
  letter-spacing: var(--tracking-title);
  line-height: 1.2;
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1 { font-size: var(--fs-h1); line-height: 1.12; }
h2 { font-size: var(--fs-h2); }
h3 { font-size: var(--fs-h3); }
p { margin-block: 0 1.2em; }
h1, h2, h3 { margin-block: 0 .7em; }
strong { font-weight: var(--weight-bold); }
small { font-size: var(--fs-small); }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; }
pre {
  max-width: 100%;
  min-width: 0;
  margin-block: 24px;
  padding: 20px;
  overflow-x: auto;
  background: var(--bg-panel-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  font-size: 14px;
  line-height: 1.8;
  overscroll-behavior-inline: contain;
}
pre code { white-space: pre; overflow-wrap: normal; word-break: normal; }
hr { border: 0; }
svg { flex-shrink: 0; }
.wrap {
  width: 100%;
  max-width: calc(var(--width-content) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.reading {
  width: 100%;
  max-width: calc(var(--width-reading) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.section {
  padding-top: var(--section-space);
  padding-bottom: var(--section-space);
}
.section--panel { background: var(--bg-panel); color: var(--text); }
.section__head { max-width: 760px; margin-bottom: 48px; }
.section__head p, .muted { color: var(--text-muted); }
.eyebrow { font-size: 13px; color: var(--text-muted); margin-bottom: 10px; }
.nowrap { white-space: nowrap; }
.accent { color: var(--accent-dark); }
.center { text-align: center; }
.grid { display: grid; gap: var(--space-grid); }
.grid--two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid > *, .flex > *, .prose, .prose > *, .panel, .card { min-width: 0; }
.flex { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.prose { line-height: 1.85; }
.prose h2 { margin-top: 64px; scroll-margin-top: calc(var(--header-h) + 24px); }
.prose h3 { margin-top: 36px; }
.prose li + li { margin-top: 10px; }
.prose a, .prose p, .prose li { overflow-wrap: break-word; }
.prose code { overflow-wrap: anywhere; }
.card, .panel {
  padding: var(--space-card);
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  box-shadow: var(--shadow-soft);
}
.card > :last-child, .panel > :last-child { margin-bottom: 0; }
.card__meta { font-size: 13px; color: var(--text-muted); }
.card__title { font-size: 21px; }
.card__title a { color: var(--text); text-decoration: none; }
.card__title a:hover { color: var(--accent-dark); }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}
.skip {
  position: absolute; left: 16px; top: -80px; z-index: var(--z-skip);
  padding: 8px 14px; background: var(--bg); color: var(--accent-dark);
  border: 1px solid var(--border); border-radius: var(--r-btn);
  font-size: 14px; text-decoration: none;
}
.skip:focus { top: 12px; }
.cta-row { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; margin-top: 24px; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  min-height: 46px; padding: 10px 22px; max-width: 100%;
  border: 1px solid var(--clear); border-radius: var(--r-btn);
  font-size: 15px; font-weight: var(--weight-bold); line-height: 1.5;
  text-align: center; text-decoration: none;
  transition: background-color var(--duration-fast) var(--ease), color var(--duration-fast) var(--ease), border-color var(--duration-fast) var(--ease);
}
.btn svg { width: 17px; height: 17px; }
.btn--primary {
  background: var(--accent); color: var(--on-accent); box-shadow: var(--shadow-btn);
}
.btn--primary:hover, .btn--primary.is-hover { background: var(--accent-dark); color: var(--on-accent); }
.btn--ghost { background: var(--bg); color: var(--text); border-color: var(--border); }
.btn--ghost svg { width: 14px; height: 14px; color: var(--text-muted); }
.btn--ghost:hover, .btn--ghost.is-hover { color: var(--accent-dark); border-color: var(--accent); }
.btn--ghost:hover svg { color: var(--accent-dark); }
.btn--text { background: var(--clear); color: var(--accent-dark); padding-inline: 0; }
.btn:disabled, .btn[aria-disabled="true"] {
  background: var(--bg-panel); color: var(--text-muted); border-color: var(--border);
  box-shadow: none; cursor: not-allowed;
}
.btn.is-focus { outline: 2px solid var(--accent-dark); outline-offset: 3px; }
.btn:active { background: var(--accent-dark); color: var(--on-accent); }

#site-header, .masthead {
  position: sticky; top: 0; z-index: var(--z-header);
  background: var(--bg); color: var(--text); border-bottom: 1px solid var(--hairline);
}
.masthead__inner {
  width: 100%;
  max-width: min(100%, calc(var(--width-header) + var(--gutter) * 2));
  min-height: var(--header-h);
  margin-inline: auto; padding-inline: var(--gutter);
  display: flex; align-items: center; gap: 32px; position: relative;
}
.brand {
  display: inline-flex; align-items: center; gap: 10px; min-width: 0;
  color: var(--text); text-decoration: none; flex-shrink: 0;
}
.brand__mark {
  display: block; width: 28px; height: 28px; flex-shrink: 0;
  border-radius: var(--r-circle);
}
.brand__placeholder {
  border-radius: var(--r-mark);
  background: linear-gradient(150deg, var(--bg), var(--bg-panel));
  color: var(--text); box-shadow: inset 0 0 0 1px var(--border);
}
.brand__name { font-size: 15px; font-weight: var(--weight-heavy); letter-spacing: -.02em; }
.brand__en { color: var(--accent); }
.primary-nav { margin-left: auto; min-width: 0; }
.primary-nav ul {
  display: flex; align-items: center; list-style: none;
  margin: 0; padding: 0; gap: clamp(14px, 1.6vw, 30px);
}
.primary-nav a {
  display: block; padding-block: 12px; color: var(--text-muted);
  font-size: 14px; font-weight: var(--weight-medium); white-space: nowrap;
  text-decoration: none; transition: color var(--duration-fast) var(--ease);
}
.primary-nav a:hover { color: var(--text); }
.primary-nav a[aria-current="page"] { color: var(--text); font-weight: var(--weight-heavy); }
.header-tools { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.language { position: relative; }
.lang {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  min-height: 34px; padding: 5px 12px;
  font-size: 13px; color: var(--text-muted); white-space: nowrap;
  background: var(--bg); border: 1px solid var(--border); border-radius: var(--r-pill);
}
.lang:hover { color: var(--text); border-color: var(--chevron); }
.lang__short { display: none; }
.language__list {
  position: absolute; top: calc(100% + 12px); right: 0; min-width: 180px;
  padding: 8px; margin: 0; list-style: none;
  background: var(--bg); color: var(--text);
  border: 1px solid var(--border); border-radius: var(--r-card); box-shadow: var(--shadow-ipad);
}
.language__list a {
  display: flex; align-items: center; width: 100%; min-height: 44px; padding: 8px 12px;
  color: var(--text); text-decoration: none; border-radius: var(--r-btn);
}
.language__list a:hover { background: var(--bg-panel); color: var(--text); }
.language__list a[aria-current="true"] { color: var(--accent-dark); font-weight: var(--weight-bold); }
.menu-toggle {
  display: none; align-items: center; justify-content: center;
  min-width: 44px; min-height: 44px; padding: 9px;
  background: var(--bg); color: var(--text);
  border: 1px solid var(--border); border-radius: var(--r-btn);
}
.menu-toggle svg { width: 22px; height: 22px; }
.mobile-nav {
  position: absolute; inset-inline: 0; top: 100%;
  padding: 16px var(--gutter) 24px;
  max-height: calc(100dvh - var(--header-h)); overflow-y: auto; overscroll-behavior: contain;
  background: var(--bg); color: var(--text);
  border-bottom: 1px solid var(--border); box-shadow: var(--shadow-soft);
}
.mobile-nav ul { margin: 0; padding: 0; list-style: none; }
.mobile-nav a {
  display: flex; align-items: center; width: 100%; min-height: 46px;
  padding: 10px 12px; color: var(--text); text-decoration: none;
}
.mobile-nav a[aria-current] { color: var(--accent-dark); font-weight: var(--weight-heavy); }
.mobile-nav__languages { margin-top: 16px !important; }
.mobile-nav__label { margin: 16px 12px 4px; font-size: 13px; color: var(--text-muted); }
.nav-veil {
  position: fixed; inset: var(--header-h) 0 0; z-index: var(--z-veil);
  background: var(--veil); color: var(--text); border: 0;
}
.site-footer { background: var(--bg-panel-2); color: var(--text); padding-top: 80px; padding-bottom: 32px; }
.footer-grid { display: grid; grid-template-columns: 1.25fr .8fr 1.1fr .7fr; gap: 48px; }
.footer-grid > * { min-width: 0; }
.footer-brand p { margin-top: 20px; max-width: 320px; color: var(--text-muted); font-size: 14px; }
.footer-heading { margin-bottom: 18px; font-size: 14px; }
.footer-links { list-style: none; margin: 0; padding: 0; }
.footer-links li + li { margin-top: 8px; }
.footer-links a { display: inline-block; padding-block: 4px; color: var(--text-muted); font-size: 14px; text-decoration: none; }
.footer-links a:hover { color: var(--accent-dark); }
.footer-bottom { margin-top: 64px; color: var(--text-muted); font-size: 12px; }
.footer-bottom p { margin-bottom: 8px; }

.reveal { opacity: 1; }
html.reveal-ready .reveal {
  opacity: 0; transform: translateY(12px);
  transition: opacity var(--duration-reveal) var(--ease), transform var(--duration-reveal) var(--ease);
}
html.reveal-ready .reveal.shown { opacity: 1; transform: none; }
.decorated, .hero { overflow-x: clip; }

@media (max-width: 1100px) {
  .primary-nav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; }
  .preview-masthead .masthead__inner { flex-wrap: wrap; gap: 6px 16px; padding-top: 12px; }
  .preview-masthead .primary-nav { display: block; order: 3; width: 100%; margin-left: 0; overflow-x: auto; }
  .preview-masthead .primary-nav ul { gap: 22px; }
}
@media (min-width: 1101px) {
  .mobile-nav, .nav-veil { display: none !important; }
}
@media (max-width: 900px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--three { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 768px) {
  :root { --fs-h1: clamp(24px, 3.8vw, 30px); }
}
@media (max-width: 640px) {
  :root { --gutter: 18px; --space-card: 22px; --space-grid: 18px; }
  .wrap, .reading { padding-inline: var(--gutter); }
  .section { padding-top: 100px; padding-bottom: 100px; }
  .grid--two, .grid--three { grid-template-columns: minmax(0, 1fr); }
  .masthead__inner { gap: 8px; }
  .header-tools { margin-left: auto; gap: 6px; }
  .brand { gap: 7px; flex-shrink: 1; }
  .brand__name { min-width: 0; font-size: 12px; overflow-wrap: anywhere; }
  .brand__mark { width: 26px; height: 26px; }
  .lang { padding-inline: 10px; min-height: 36px; }
  .lang__full { display: none; }
  .lang__short { display: inline; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: 32px; }
  .footer-bottom { margin-top: 40px; }
  .tilt, [data-tilt] { transform: none !important; }
  .section__head { margin-bottom: 32px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  html.reveal-ready .reveal { opacity: 1; transform: none; }
}