:root {
  --ink: #10222c;
  --muted: #5f7682;
  --line: rgba(16, 34, 44, .12);
  --paper: #f8fbfc;
  --aqua-0: #e8faff;
  --aqua-1: #bfeffd;
  --aqua-2: #35bce8;
  --aqua-3: #148dbd;
  --aqua-4: #075c8d;
  --yellow: #ffd646;
  --warm: #f3e7d4;
  --warm-dark: #3b2d21;
  --shadow: 0 18px 50px rgba(7, 92, 141, .13);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Inter, "Noto Sans JP", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
button, a { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 3px solid var(--yellow); outline-offset: 4px; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid rgba(255,255,255,.35);
  background: rgba(248, 251, 252, .86);
  backdrop-filter: blur(18px);
}
.header-inner {
  width: min(1440px, calc(100% - 40px));
  min-height: 68px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.brand {
  font-weight: 900;
  letter-spacing: -.04em;
  font-size: 1.2rem;
}
.nav { display: flex; align-items: center; gap: 28px; font-size: .9rem; font-weight: 800; letter-spacing: .08em; }
.nav a { opacity: .72; transition: opacity .2s ease, transform .2s ease; }
.nav a:hover { opacity: 1; transform: translateY(-1px); }
.lang-pill {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255,255,255,.7);
}

.hero-grid {
  min-height: calc(100svh - 68px);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  overflow: hidden;
}
.game-panel {
  position: relative;
  min-height: 680px;
  padding: clamp(42px, 6vw, 90px);
  display: flex;
  align-items: flex-end;
  overflow: hidden;
  isolation: isolate;
  transition: flex .45s ease, filter .45s ease;
}
.game-panel::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -2;
  background: linear-gradient(180deg, rgba(255,255,255,.04), rgba(7,16,24,.34));
}
.game-panel.stack {
  color: #fff8ed;
  background:
    radial-gradient(circle at 78% 20%, rgba(245,221,174,.34), transparent 27%),
    linear-gradient(135deg, #6e5743, #34271e 70%);
}
.game-panel.stack::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -3;
  opacity: .22;
  background-image: repeating-linear-gradient(0deg, transparent 0 22px, rgba(255,255,255,.06) 23px 24px);
}
.game-panel.aqua {
  color: #073e5c;
  background:
    radial-gradient(circle at 78% 20%, rgba(255,255,255,.8), transparent 18%),
    radial-gradient(circle at 20% 28%, rgba(255,255,255,.5), transparent 12%),
    linear-gradient(145deg, #e8faff 4%, #8bdef5 48%, #35bce8 100%);
}
.panel-content { width: min(560px, 100%); position: relative; z-index: 2; }
.eyebrow { margin: 0 0 12px; text-transform: uppercase; letter-spacing: .18em; font-size: .78rem; font-weight: 900; opacity: .72; }
.panel-title { margin: 0; font-size: clamp(2.4rem, 5vw, 5.5rem); line-height: .96; letter-spacing: -.06em; }
.panel-copy { margin: 20px 0 28px; max-width: 42ch; font-size: clamp(1rem, 1.4vw, 1.15rem); }
.badge { display: inline-flex; align-items: center; min-height: 34px; padding: 0 12px; border-radius: 999px; font-size: .78rem; font-weight: 900; letter-spacing: .08em; background: rgba(255,255,255,.18); border: 1px solid rgba(255,255,255,.32); }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 50px;
  padding: 0 22px;
  border-radius: 999px;
  font-weight: 900;
  letter-spacing: .02em;
  transition: transform .2s ease, box-shadow .2s ease, background .2s ease;
}
.btn:hover { transform: translateY(-2px); }
.btn-dark { background: #092f44; color: #fff; box-shadow: 0 12px 30px rgba(7,92,141,.24); }
.btn-light { background: rgba(255,255,255,.84); color: #17303d; box-shadow: 0 12px 30px rgba(0,0,0,.12); }
.btn-outline { border: 1px solid rgba(7,92,141,.2); background: rgba(255,255,255,.66); }

.pipe-art { position: absolute; inset: 0; pointer-events: none; z-index: 1; }
.pipe {
  position: absolute;
  height: 54px;
  border-radius: 999px;
  background: linear-gradient(180deg, #fff 0%, #eefbff 52%, #b8e7f4 100%);
  box-shadow: inset 0 -8px 0 rgba(7,92,141,.08), 0 10px 20px rgba(7,92,141,.12);
  border: 1px solid rgba(7,92,141,.1);
}
.pipe::after { content: ""; position: absolute; inset: 11px; border-radius: inherit; background: linear-gradient(90deg, rgba(53,188,232,.16), rgba(53,188,232,.62), rgba(53,188,232,.16)); }
.pipe-a { width: 300px; top: 18%; right: -70px; transform: rotate(-18deg); }
.pipe-b { width: 250px; top: 41%; right: 11%; transform: rotate(90deg); }
.pipe-c { width: 220px; top: 58%; right: -20px; transform: rotate(18deg); }
.bubble { position: absolute; border-radius: 50%; border: 2px solid rgba(255,255,255,.65); background: rgba(255,255,255,.16); box-shadow: inset 0 0 18px rgba(255,255,255,.35); }
.b1 { width: 62px; height: 62px; right: 18%; top: 12%; }
.b2 { width: 28px; height: 28px; right: 37%; top: 24%; }
.b3 { width: 44px; height: 44px; right: 8%; top: 67%; }

.section { padding: clamp(72px, 8vw, 120px) 20px; }
.section-inner { width: min(1240px, 100%); margin: 0 auto; }
.section-kicker { margin: 0 0 10px; font-size: .78rem; font-weight: 900; letter-spacing: .18em; text-transform: uppercase; color: var(--aqua-4); }
.section-title { margin: 0; font-size: clamp(2rem, 5vw, 4.4rem); line-height: 1.03; letter-spacing: -.055em; }
.section-lead { max-width: 680px; margin: 22px 0 0; color: var(--muted); font-size: 1.06rem; }

.about-grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: 48px; align-items: start; }
.info-card { padding: 28px; border-radius: 28px; background: #fff; border: 1px solid var(--line); box-shadow: 0 18px 50px rgba(16,34,44,.06); }
.info-card h3 { margin: 0 0 8px; }
.info-card p { margin: 0; color: var(--muted); }

.aqua-hero {
  min-height: calc(100svh - 68px);
  position: relative;
  display: grid;
  place-items: center;
  overflow: hidden;
  background:
    radial-gradient(circle at 78% 22%, rgba(255,255,255,.92), transparent 20%),
    radial-gradient(circle at 15% 74%, rgba(255,255,255,.46), transparent 18%),
    linear-gradient(145deg, #e8faff, #bfeffd 48%, #79d9f2);
}
.aqua-hero-inner { width: min(1240px, calc(100% - 40px)); margin: 0 auto; padding: 84px 0; position: relative; z-index: 3; }
.aqua-title { margin: 0; font-size: clamp(4rem, 10vw, 9.5rem); line-height: .82; letter-spacing: -.08em; color: #075c8d; text-shadow: 0 12px 28px rgba(7,92,141,.12); }
.aqua-subtitle { margin: 24px 0 0; font-size: clamp(1.2rem, 2.2vw, 2rem); font-weight: 800; color: #148dbd; }
.aqua-tagline { margin: 30px 0 0; font-size: clamp(.95rem, 1.3vw, 1.1rem); font-weight: 900; letter-spacing: .2em; color: #0d789f; }
.aqua-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }

.mechanic-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 48px; }
.step-card { padding: 28px; border-radius: 30px; background: #fff; border: 1px solid rgba(20,141,189,.13); box-shadow: var(--shadow); }
.step-number { display: grid; place-items: center; width: 42px; height: 42px; border-radius: 50%; background: var(--aqua-0); color: var(--aqua-4); font-weight: 900; }
.step-card h3 { margin: 22px 0 8px; font-size: 1.3rem; }
.step-card p { margin: 0; color: var(--muted); }
.pipe-demo { height: 150px; margin-top: 24px; display: grid; place-items: center; border-radius: 22px; background: linear-gradient(145deg, #f4fdff, #daf6fd); overflow: hidden; }
.demo-pipe { width: 130px; height: 34px; border-radius: 999px; background: linear-gradient(180deg,#fff,#cdeef7); border: 1px solid rgba(7,92,141,.12); position: relative; box-shadow: inset 0 -6px 0 rgba(7,92,141,.07); }
.demo-pipe.flow::after { content: ""; position: absolute; left: 10px; right: 10px; top: 11px; height: 10px; border-radius: 999px; background: linear-gradient(90deg,#35bce8,#89e8ff,#35bce8); background-size: 200% 100%; animation: flow 1.8s linear infinite; }
.demo-rotate { transform: rotate(90deg); }

.challenge-band { background: #082f45; color: #fff; }
.challenge-grid { margin-top: 42px; display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.challenge { padding: 24px; border-radius: 22px; background: rgba(255,255,255,.08); border: 1px solid rgba(255,255,255,.12); }
.challenge strong { display: block; font-size: 1.2rem; }
.challenge span { opacity: .66; font-size: .9rem; }

.feature-split { display: grid; grid-template-columns: .9fr 1.1fr; align-items: center; gap: clamp(34px, 7vw, 90px); }
.mock-phone { max-width: 420px; margin: 0 auto; padding: 14px; border-radius: 44px; background: #0a344a; box-shadow: 0 28px 80px rgba(7,92,141,.28); }
.mock-screen { aspect-ratio: 9 / 16; border-radius: 32px; overflow: hidden; position: relative; background: linear-gradient(180deg,#dff8ff,#7fdcf3); border: 1px solid rgba(255,255,255,.24); }
.mock-screen::before { content: "AQUA PIPE"; position: absolute; top: 11%; left: 0; right: 0; text-align: center; font-size: clamp(1.2rem, 3vw, 2rem); font-weight: 950; color: #075c8d; letter-spacing: -.04em; }
.mock-grid { position: absolute; left: 9%; right: 9%; top: 28%; aspect-ratio: 1; display: grid; grid-template-columns: repeat(4, 1fr); gap: 7px; }
.tile { border-radius: 14px; background: rgba(255,255,255,.8); border: 1px solid rgba(7,92,141,.12); box-shadow: inset 0 -5px 0 rgba(7,92,141,.07); position: relative; }
.tile::after { content: ""; position: absolute; left: 18%; right: 18%; top: 42%; height: 16%; border-radius: 99px; background: #35bce8; opacity: .8; }
.star-row { display: flex; gap: 8px; margin: 24px 0 0; font-size: 2.3rem; color: var(--yellow); }

.cta-panel { text-align: center; padding: clamp(50px, 8vw, 90px) 24px; border-radius: 42px; background: linear-gradient(145deg,#dff8ff,#fff); border: 1px solid rgba(20,141,189,.14); }
.cta-panel p { color: var(--muted); }

.site-footer { padding: 38px 20px 54px; border-top: 1px solid var(--line); background: #f4f8fa; }
.footer-inner { width: min(1240px,100%); margin: 0 auto; display: flex; justify-content: space-between; gap: 30px; flex-wrap: wrap; }
.footer-links { display: flex; gap: 20px; flex-wrap: wrap; color: var(--muted); font-size: .9rem; }

@keyframes flow { from { background-position: 0 0; } to { background-position: 200% 0; } }

@media (hover:hover) and (min-width: 1024px) {
  .hero-grid:hover .game-panel { filter: saturate(.82) brightness(.92); }
  .hero-grid .game-panel:hover { filter: none; }
  .game-panel:hover .panel-content { transform: translateY(-4px); }
  .panel-content { transition: transform .35s ease; }
}

@media (max-width: 900px) {
  .nav a:not(.lang-pill) { display: none; }
  .hero-grid { grid-template-columns: 1fr; }
  .game-panel { min-height: 72svh; }
  .about-grid, .feature-split { grid-template-columns: 1fr; }
  .mechanic-grid { grid-template-columns: 1fr; }
  .challenge-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 560px) {
  .header-inner { width: min(100% - 28px, 1440px); min-height: 62px; }
  .brand { font-size: 1.05rem; }
  .lang-pill { min-height: 36px; padding: 0 11px; }
  .game-panel { min-height: 66svh; padding: 34px 22px; }
  .aqua-hero-inner { width: min(100% - 32px, 1240px); }
  .aqua-title { font-size: clamp(3.8rem, 22vw, 6.4rem); }
  .challenge-grid { grid-template-columns: 1fr; }
  .section { padding-left: 16px; padding-right: 16px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; animation-iteration-count: 1 !important; scroll-behavior: auto !important; transition-duration: .001ms !important; }
}