:root {
  --bg: #F3F3F3;
  --panel: #FFFFFF;
  --panel-2: #E8E8E8;
  --border: #DADADA;
  --accent: #1F6E9C;
  --accent-dark: #164F72;
  --text: #1E2328;
  --text-muted: #5E656C;
  --success: #2E9E6B;
  --warn: #D98B12;
  --error: #D2453A;
  --grass: #3BB89A;
  --grass-deep: #2B9A7F;
  --apricot: #F28C38;
  --apricot-deep: #D47425;
  --sky-top: #C9E7F8;
  --sky-bottom: #DFF5F3;
  --sky-soft: #E4F4FB;
  --cloud: #FFFFFF;
  --mount-far: #C2E5EC;
  --hill-1: #B0E4DE;
  --hill-2: #93D8CE;
  --hill-3: #7ECDC2;
  --hill-4: #67C2B5;
  --shrub-back: #2AA096;
  --shrub: #17837D;
  --water: #C2E6FA;
  --water-bank: #86C5E7;
  --water-hi: rgba(255, 255, 255, .85);
  --stone: #CFD9DC;
  --stone-hi: #EEF3F4;
  --post: #4F6B70;
  --veil: rgba(255, 255, 255, .5);
  --veil-line: rgba(255, 255, 255, .78);
  --chip-bg: rgba(255, 255, 255, .72);
  --line-sky: rgba(22, 79, 114, .14);
  --dot-ring: rgba(46, 158, 107, .18);
  --scrim: rgba(30, 35, 40, .32);
  --clear: transparent;
  --font-display: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans", "Hiragino Sans GB", "Microsoft YaHei", "Yu Gothic", "Malgun Gothic", "Apple SD Gothic Neo", system-ui, sans-serif;
  --font-body: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Hiragino Kaku Gothic ProN", "Meiryo", "Malgun Gothic", "Apple SD Gothic Neo", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, "Liberation Mono", monospace;
  --r-card: 24px;
  --r-card-lg: 28px;
  --r-md: 14px;
  --r-sm: 10px;
  --r-pill: 999px;
  --r-round: 50%;
  --gutter: 112px;
  --content-width: 1216px;
  --reading-width: 800px;
  --header-content-width: 1280px;
  --header-height: 76px;
  --weight-normal: 400;
  --weight-medium: 500;
  --weight-strong: 600;
  --size-body: 16px;
  --size-small: 14px;
  --size-h1: clamp(34px, 2.2vw + 14px, 46px);
  --size-h2: clamp(26px, 2.4vw, 34px);
  --size-h3: 22px;
  --ease: cubic-bezier(.4, .1, .2, 1);
  --time-fast: .2s;
  --time-reveal: .65s;
  --section-space: 96px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 28px; }
html.nav-open { overflow: hidden; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: var(--weight-normal) var(--size-body)/1.6 var(--font-body);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img, svg { max-width: 100%; vertical-align: middle; }
img { height: auto; }
button, input, select, textarea { font: inherit; }
button { cursor: pointer; }
a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: .22em; }
a:hover { color: var(--accent-dark); }
button, a { -webkit-tap-highlight-color: var(--clear); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; }
[hidden] { display: none !important; }
h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: var(--weight-normal);
  line-height: 1.25;
  letter-spacing: -.01em;
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1 { font-size: var(--size-h1); line-height: 1.2; letter-spacing: -.012em; }
h2 { font-size: var(--size-h2); }
h3 { font-size: var(--size-h3); }
p { margin: 0 0 1.25em; }
strong { font-weight: var(--weight-strong); }
em.accent, h1 em { color: var(--accent); font-style: normal; }
.word { white-space: nowrap; }
.muted { color: var(--text-muted); }
.small { font-size: var(--size-small); }
.mono, code, pre { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; font-size: .9em; }
pre {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  tab-size: 2;
}
pre code { overflow-wrap: normal; word-break: normal; white-space: pre; font-size: 13px; }
ul, ol { padding-inline-start: 1.5em; }
li + li { margin-top: .3em; }
hr { border: 0; border-top: 1px solid var(--border); margin-block: 32px; }
.wrap {
  width: 100%;
  max-width: calc(var(--content-width) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
  min-width: 0;
}
.reading { max-width: calc(var(--reading-width) + var(--gutter) * 2); }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.section-head { max-width: 680px; margin-bottom: 40px; }
.section-head h2 { margin-top: 0; margin-bottom: 14px; }
.section-head p { color: var(--text-muted); font-size: 17px; }
.center { text-align: center; margin-inline: auto; }
.grid { display: grid; gap: 24px; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid > *, .flex > *, .feature-tabs > *, .footer-grid > * { min-width: 0; }
.flex { display: flex; flex-wrap: wrap; align-items: center; gap: 14px; }
.panel, .card {
  min-width: 0;
  padding: 32px;
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  background: var(--panel);
  color: var(--text);
}
.panel { border-radius: var(--r-card-lg); }
.card h3, .panel h3 { margin-top: 0; }
.card p:last-child, .panel p:last-child { margin-bottom: 0; }
.panel-muted { background: var(--panel-2); color: var(--text); }
.prose, .article-body { min-width: 0; overflow-wrap: break-word; }
.prose h2, .article-body h2 { margin-top: 2.4em; }
.prose h3, .article-body h3 { margin-top: 1.8em; }
.prose p, .article-body p { line-height: 1.85; }
.prose img, .article-body img { max-width: 100%; }
.prose section, .article-body section { scroll-margin-top: 28px; }
.btn {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  min-height: 52px;
  padding: 12px 28px;
  border: 1px solid var(--accent);
  border-radius: var(--r-pill);
  background: var(--clear);
  color: var(--accent);
  font-size: 16px;
  font-weight: var(--weight-medium);
  line-height: 1.5;
  letter-spacing: .01em;
  text-decoration: none;
  text-align: center;
  transition: background-color var(--time-fast) var(--ease), color var(--time-fast) var(--ease), border-color var(--time-fast) var(--ease);
}
.btn svg { width: 18px; height: 18px; flex-shrink: 0; }
.btn-main { background: var(--accent); color: var(--panel); }
.btn-main:hover, .btn-main.is-hover { background: var(--accent-dark); border-color: var(--accent-dark); color: var(--panel); }
.btn-sub { background: var(--panel); color: var(--accent); border-color: var(--line-sky); padding-inline: 24px; }
.btn-sub:hover, .btn-sub.is-hover { border-color: var(--accent); color: var(--accent-dark); }
.btn:active, .btn.is-active { background: var(--accent-dark); color: var(--panel); border-color: var(--accent-dark); }
.btn:disabled, .btn[aria-disabled="true"] { background: var(--panel-2); color: var(--text-muted); border-color: var(--border); cursor: not-allowed; }
.btn.is-focus { outline: 2px solid var(--accent); outline-offset: 3px; }
.icon { width: 20px; height: 20px; flex-shrink: 0; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}
.skip-link { position: fixed; left: var(--gutter); top: 12px; z-index: 100; }
.skip-link:not(:focus) {
  width: 1px;
  height: 1px;
  min-height: 0;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.topbar {
  position: relative;
  z-index: 30;
  background: var(--veil);
  color: var(--text);
  border-bottom: 1px solid var(--veil-line);
}
.hero-page .topbar { position: absolute; inset: 0 0 auto; }
.topbar-in {
  position: relative;
  max-width: min(100%, calc(var(--header-content-width) + var(--gutter) * 2));
  margin-inline: auto;
  height: var(--header-height);
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 32px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
  color: var(--text);
  text-decoration: none;
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: var(--weight-medium);
  letter-spacing: -.005em;
}
.brand:hover { color: var(--accent); }
.brand-mark { width: 34px; height: 34px; flex-shrink: 0; }
.mainnav { margin-left: auto; min-width: 0; }
.mainnav ul {
  display: flex;
  align-items: center;
  gap: 40px;
  list-style: none;
  margin: 0;
  padding: 0;
}
.mainnav li { margin: 0; }
.mainnav a {
  display: block;
  padding-block: 12px;
  color: var(--text);
  text-decoration: none;
  font-size: 15px;
  white-space: nowrap;
  transition: color var(--time-fast) var(--ease);
}
.mainnav a:hover { color: var(--accent); }
.mainnav a[aria-current="page"] { font-weight: var(--weight-strong); }
.header-tools { display: flex; align-items: center; gap: 8px; flex-shrink: 0; }
.language { position: relative; }
.lang {
  appearance: none;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  min-height: 36px;
  padding: 6px 16px;
  border: 1px solid var(--line-sky);
  border-radius: var(--r-pill);
  background: var(--chip-bg);
  color: var(--text);
  font-size: 14px;
  line-height: 1.5;
  white-space: nowrap;
}
.lang:hover { border-color: var(--accent); }
.lang-short { display: none; }
.language-list {
  position: absolute;
  right: 0;
  top: calc(100% + 12px);
  min-width: 180px;
  padding: 8px;
  list-style: none;
  margin: 0;
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  background: var(--panel);
  color: var(--text);
  z-index: 34;
}
.language-list li { margin: 0; }
.language-list a { display: block; min-height: 44px; padding: 10px 14px; color: var(--text); text-decoration: none; border-radius: var(--r-sm); }
.language-list a:hover, .language-list a[aria-current] { background: var(--bg); color: var(--accent-dark); }
.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  padding: 10px;
  border: 1px solid var(--line-sky);
  border-radius: var(--r-pill);
  background: var(--chip-bg);
  color: var(--text);
}
.menu-toggle svg { width: 22px; height: 22px; }
.mobile-drawer { display: none; }
.nav-veil { position: fixed; inset: 0; z-index: 20; border: 0; background: var(--scrim); color: var(--text); }
.preview-menu { display: none; }
details.language > summary { list-style: none; cursor: pointer; }
details.language > summary::-webkit-details-marker { display: none; }

.hero {
  position: relative;
  height: clamp(760px, 58.34vw, 880px);
  overflow: hidden;
  overflow-x: clip;
  background: linear-gradient(180deg, var(--sky-top), var(--sky-bottom));
  color: var(--text);
}
.hero-visual { position: absolute; inset: 0; pointer-events: none; }
.scene { display: block; width: 100%; height: 100%; }
.hero-in {
  position: relative;
  z-index: 2;
  max-width: 1440px;
  margin-inline: auto;
  padding: 156px var(--gutter) 0;
}
.hero-copy { width: min(540px, 44vw); }
.badge {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-height: 32px;
  max-width: 100%;
  padding: 5px 16px 5px 12px;
  border: 1px solid var(--line-sky);
  border-radius: var(--r-pill);
  background: var(--chip-bg);
  color: var(--text-muted);
  font-size: 13.5px;
}
.badge-dot { width: 8px; height: 8px; flex-shrink: 0; border-radius: var(--r-round); background: var(--success); box-shadow: 0 0 0 4px var(--dot-ring); }
.badge b { color: var(--text); font-weight: var(--weight-medium); }
.hero h1 { margin: 26px 0 0; }
.h1-line { display: block; }
.cta { display: flex; align-items: center; flex-wrap: wrap; gap: 14px; margin-top: 30px; }
.lede { margin: 26px 0 0; max-width: 31em; font-size: 17px; line-height: 1.75; color: var(--text-muted); }
.lede strong { color: var(--text); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 22px 0 0; padding: 0; list-style: none; }
.chips li, .tag {
  display: inline-flex;
  align-items: center;
  min-height: 30px;
  max-width: 100%;
  margin: 0;
  padding: 4px 12px;
  border: 1px solid var(--line-sky);
  border-radius: var(--r-pill);
  background: var(--chip-bg);
  color: var(--accent-dark);
  font-family: var(--font-mono);
  font-size: 12.5px;
  overflow-wrap: anywhere;
}
.platforms { display: flex; align-items: center; flex-wrap: wrap; gap: 18px; margin-top: 30px; }
.plat-label { font-size: 13px; color: var(--text-muted); white-space: nowrap; }
.plat-rule { width: 1px; height: 18px; background: var(--line-sky); flex-shrink: 0; }
.platforms ul { display: flex; flex-wrap: wrap; align-items: center; gap: 22px; list-style: none; margin: 0; padding: 0; }
.platforms li { margin: 0; }
.platforms a { display: inline-flex; align-items: center; gap: 8px; min-height: 44px; font-size: 14px; color: var(--text); text-decoration: none; }
.platforms a:hover { color: var(--accent); }
.plat-ico { width: 32px; height: 32px; border-radius: var(--r-round); display: inline-grid; place-items: center; background: var(--panel); color: var(--text); border: 1px solid var(--line-sky); flex-shrink: 0; }
.plat-ico svg { width: 15px; height: 15px; }
.plat-ico svg.tux { width: 14px; height: 16px; }

.g-sky-a { stop-color: var(--sky-top); }
.g-sky-b { stop-color: var(--sky-bottom); }
.sky-soft { fill: var(--sky-soft); }
.cloud { fill: var(--cloud); }
.mount-far { fill: var(--mount-far); }
.hill-1 { fill: var(--hill-1); }
.hill-2 { fill: var(--hill-2); }
.hill-3 { fill: var(--hill-3); }
.hill-4 { fill: var(--hill-4); }
.bank { fill: none; stroke: var(--water-bank); stroke-linecap: round; stroke-linejoin: round; }
.water { fill: none; stroke: var(--water); stroke-linecap: round; stroke-linejoin: round; }
.glint { fill: none; stroke: var(--water-hi); stroke-width: 2; stroke-linecap: round; stroke-dasharray: 10 26; }
.pool-bank { fill: var(--water-bank); }
.pool { fill: var(--water); }
.pool-hi { fill: var(--water-hi); }
.stone { fill: var(--stone); }
.stone-hi { fill: var(--stone-hi); }
.post { fill: var(--post); }
.board-in { fill: var(--panel); }
.board-in-edge { fill: var(--border); }
.board-direct { fill: var(--grass); }
.board-direct-edge { fill: var(--grass-deep); }
.board-proxy { fill: var(--accent); }
.board-proxy-edge { fill: var(--accent-dark); }
.board-block { fill: var(--apricot); }
.board-block-edge { fill: var(--apricot-deep); }
.sign-text { font-family: var(--font-mono); font-size: 15px; font-weight: var(--weight-strong); fill: var(--panel); }
.board-direct-label, .board-block-label { fill: var(--text); }
.sign-text-in { font-family: var(--font-mono); font-size: 12px; font-weight: var(--weight-medium); fill: var(--accent-dark); }
.note { fill: var(--panel); stroke: var(--border); stroke-width: 1; }
.note-pin { fill: var(--grass); }
.note-code { font-family: var(--font-mono); font-size: 13px; fill: var(--text); }
.note-key { fill: var(--accent-dark); }
.note-tag { font-family: var(--font-mono); font-size: 13px; font-weight: var(--weight-strong); fill: var(--accent-dark); }
.note-arrow { font-family: var(--font-mono); font-size: 13px; fill: var(--text-muted); }
.guide { fill: none; stroke: var(--accent-dark); stroke-width: 1.5; stroke-linecap: round; stroke-dasharray: 4 5; }
.guide-head { fill: none; stroke: var(--accent-dark); stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
.leaf-g { fill: var(--grass); }
.leaf-b { fill: var(--accent); }
.leaf-o { fill: var(--apricot); }
.vein { fill: none; stroke: var(--water-hi); stroke-width: 1.2; stroke-linecap: round; }
.shrub-back { fill: var(--shrub-back); }
.shrub { fill: var(--shrub); }
.wave { fill: var(--bg); }
.wave-panel { fill: var(--panel); }
.boat { transform-box: fill-box; transform-origin: center; animation: leaf-drift 5.6s ease-in-out infinite; }
.boat.b2 { animation-delay: -1.9s; }
.boat.b3 { animation-delay: -3.7s; }
@keyframes leaf-drift {
  0%, 100% { transform: translate(-2px, 0) rotate(-4deg); }
  50% { transform: translate(2.5px, -1.5px) rotate(4deg); }
}
.next { padding: 24px var(--gutter) 64px; text-align: center; }
.next h2 { margin: 0; }
.next p { margin: 14px auto 0; max-width: 36em; font-size: 17px; color: var(--text-muted); }
.wave-section { position: relative; overflow-x: clip; background: var(--panel); color: var(--text); }
.section-wave { display: block; width: 100%; height: 70px; background: var(--bg); color: var(--text); }
.reveal { opacity: 1; transform: none; }
.reveal.is-waiting { opacity: 0; transform: translateY(14px); }
.reveal.shown { opacity: 1; transform: none; transition: opacity var(--time-reveal) var(--ease), transform var(--time-reveal) var(--ease); }

.site-footer { background: var(--panel-2); color: var(--text); padding-top: 64px; padding-bottom: 28px; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1.2fr 1fr; gap: 36px; }
.footer-brand p { color: var(--text-muted); font-size: 14px; max-width: 24em; margin-top: 20px; }
.footer-heading { font-size: 15px; font-weight: var(--weight-medium); margin: 0 0 16px; }
.footer-links { list-style: none; margin: 0; padding: 0; }
.footer-links li { margin: 0; }
.footer-links a { display: block; width: fit-content; padding-block: 6px; color: var(--text-muted); text-decoration: none; font-size: 14px; }
.footer-links a:hover { color: var(--accent-dark); }
.footer-links a[aria-current] { color: var(--text); }
.footer-bottom { border-top: 1px solid var(--border); padding-top: 22px; margin-top: 40px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px 24px; font-size: 13px; color: var(--text-muted); }
.footer-bottom p { margin: 0; }
.footer-legal { display: flex; flex-wrap: wrap; gap: 24px; }
.footer-legal a { color: var(--text-muted); }

@media (max-width: 1180px) {
  :root { --gutter: 56px; }
  .topbar-in { gap: 24px; }
  .mainnav ul { gap: 28px; }
}
@media (max-width: 1000px) {
  .mainnav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; }
  .mobile-drawer:not([hidden]) {
    display: block;
    position: absolute;
    inset: var(--header-height) 0 auto;
    padding: 18px var(--gutter) 28px;
    max-height: calc(100dvh - var(--header-height));
    overflow-y: auto;
    overscroll-behavior: contain;
    border-bottom: 1px solid var(--border);
    background: var(--panel);
    color: var(--text);
    z-index: 33;
  }
  .mobile-drawer ul { list-style: none; margin: 0; padding: 0; }
  .mobile-drawer li { margin: 0; }
  .mobile-drawer a { display: block; width: 100%; min-height: 46px; padding: 11px 12px; color: var(--text); text-decoration: none; border-radius: var(--r-sm); }
  .mobile-drawer a:hover, .mobile-drawer a[aria-current] { background: var(--bg); color: var(--accent-dark); }
  .drawer-label { margin: 18px 12px 8px; color: var(--text-muted); font-size: 13px; }
  .preview-menu { display: block; }
  .preview-menu summary { list-style: none; cursor: pointer; }
  .preview-menu summary::-webkit-details-marker { display: none; }
  .preview-menu .mobile-drawer { top: var(--header-height); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 768px) {
  :root { --size-h1: clamp(24px, 4vw, 30px); --section-space: 64px; }
}
@media (max-width: 760px) {
  :root { --gutter: 20px; --header-height: 64px; }
  .hero { height: auto; display: flex; flex-direction: column; }
  .hero-in { padding-top: 104px; order: 1; width: 100%; }
  .hero-copy { width: 100%; }
  .hero-visual { position: relative; order: 2; height: 380px; margin-top: 24px; }
  .platforms { gap: 12px; }
  .platforms ul { gap: 14px; }
  .plat-rule { display: none; }
  .next h2 { font-size: 26px; }
  .brand { font-size: 16px; gap: 8px; }
  .topbar-in { gap: 12px; }
}
@media (max-width: 640px) {
  .grid { grid-template-columns: minmax(0, 1fr); }
  .panel, .card { padding: 24px; }
  .tilt, [data-tilt] { transform: none !important; }
  .chips { flex-direction: row; flex-wrap: wrap; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: 28px; }
  .lang-full { display: none; }
  .lang-short { display: inline; }
  .lang { min-height: 44px; padding-inline: 12px; }
  pre { padding: 18px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .reveal.is-waiting { opacity: 1; transform: none; }
}