:root {
  color-scheme: light dark;
  --background: #f4f8fa;
  --surface: #ffffff;
  --surface-subtle: #edf3f6;
  --text: #0b1720;
  --muted: #425461;
  --border: #cbd8df;
  --interactive: #004f8c;
  --interactive-hover: #00365f;
  --primary: #005999;
  --primary-hover: #004373;
  --digit-span: #007f9a;
  --n-back: #6842c2;
  --percentage: #1769aa;
  --planning: #9a5200;
  --probability: #9b2f67;
  --magnitude: #09745a;
  --hero-glow-one: rgb(0 127 154 / 12%);
  --hero-glow-two: rgb(104 66 194 / 10%);
  --shadow: 0 14px 40px rgb(15 38 51 / 8%);
  --radius-control: 12px;
  --radius-card: 16px;
  --radius-hero: 20px;
  --ratio-golden: 1.618;
  --ratio-silver: 1.414;
  --space-silver-sm: 0.707rem;
  --space-silver-md: 1.414rem;
  --space-silver-lg: 2rem;
  --space-silver-xl: 2.828rem;
  --content-width: 70rem;
  --reading-width: 44rem;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  font-size: 1rem;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

:lang(ja) {
  line-break: strict;
}

img {
  display: block;
  max-width: 100%;
}

a {
  color: var(--interactive);
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--interactive-hover);
}

a:focus-visible,
button:focus-visible {
  outline: 3px solid var(--interactive);
  outline-offset: 4px;
  border-radius: 4px;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 0.75rem;
  left: 0.75rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-control);
  background: var(--text);
  color: var(--surface);
  font-weight: 700;
  transform: translateY(-180%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--background) 94%, transparent);
}

.nav,
.container,
.reading-container {
  width: min(100% - 2rem, var(--content-width));
  margin-inline: auto;
}

.reading-container {
  max-width: var(--reading-width);
}

.nav {
  display: flex;
  min-height: 4.5rem;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.brand-link {
  display: inline-flex;
  min-height: 2.75rem;
  align-items: center;
  gap: 0.7rem;
  color: var(--text);
  font-size: 1.05rem;
  font-weight: 750;
  text-decoration: none;
}

.brand-mark {
  width: 2rem;
  height: 2rem;
}

.nav-links {
  display: flex;
  min-width: 0;
  align-items: center;
  justify-content: flex-end;
  flex-wrap: wrap;
  gap: 0.35rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  display: inline-flex;
  min-height: 2.75rem;
  align-items: center;
  padding: 0.45rem 0.7rem;
  border-radius: var(--radius-control);
  color: var(--text);
  font-size: 0.92rem;
  font-weight: 650;
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a[aria-current="page"] {
  background: var(--surface-subtle);
}

.hero {
  position: relative;
  display: grid;
  grid-template-areas:
    "visual"
    "content";
  grid-template-columns: minmax(0, 1fr);
  align-items: center;
  gap: var(--space-silver-md);
  margin-block: var(--space-silver-md) var(--space-silver-xl);
  padding: clamp(1.25rem, 5vw, 2rem);
  border: 1px solid var(--border);
  border-radius: var(--radius-hero);
  background:
    radial-gradient(circle at 12% 20%, var(--hero-glow-one), transparent 34%),
    radial-gradient(circle at 88% 10%, var(--hero-glow-two), transparent 30%),
    var(--surface);
  box-shadow: var(--shadow);
}

.hero-content {
  grid-area: content;
  min-width: 0;
  max-width: none;
}

.hero h1 {
  font-size: clamp(1.875rem, 8.2vw, 2.625rem);
  letter-spacing: -0.025em;
  line-height: 1.16;
}

.hero-visual {
  grid-area: visual;
  width: min(100%, 34rem);
  min-width: 0;
  margin: 0;
  justify-self: center;
}

.hero-visual img {
  width: 100%;
  height: auto;
  aspect-ratio: 1200 / 630;
  border: 1px solid var(--border);
  border-radius: var(--radius-control);
  background: #02041c;
  box-shadow: 0 18px 42px rgb(2 4 28 / 18%);
  object-fit: cover;
}

.hero-title-line {
  display: block;
  overflow-wrap: anywhere;
}

:lang(ja) .hero h1 {
  letter-spacing: -0.02em;
}

.eyebrow {
  margin: 0 0 0.65rem;
  color: var(--interactive);
  font-size: 0.85rem;
  font-weight: 750;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  margin-top: 0;
  line-height: 1.25;
  overflow-wrap: break-word;
  text-wrap: balance;
}

p,
li,
dd {
  overflow-wrap: break-word;
}

h1 {
  margin-bottom: 1rem;
  font-size: clamp(2.35rem, 8vw, 5rem);
  letter-spacing: -0.045em;
}

.reading-container h1 {
  font-size: clamp(2rem, 6vw, 3.5rem);
}

h2 {
  margin-bottom: 1rem;
  font-size: clamp(1.65rem, 4vw, 2.4rem);
  letter-spacing: -0.025em;
}

h3 {
  margin-bottom: 0.5rem;
  font-size: 1.2rem;
}

.lead {
  max-width: 42rem;
  margin: 0;
  color: var(--muted);
  font-size: clamp(1.08rem, 2.5vw, 1.3rem);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-silver-sm);
  margin-top: var(--space-silver-md);
}

.button {
  display: inline-flex;
  max-width: 100%;
  min-height: 3rem;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-control);
  background: var(--surface);
  color: var(--text);
  font-weight: 750;
  white-space: normal;
  overflow-wrap: anywhere;
  text-align: center;
  text-decoration: none;
}

.button.primary {
  border-color: var(--primary);
  background: var(--primary);
  color: #ffffff;
}

.button.primary:hover {
  border-color: var(--primary-hover);
  background: var(--primary-hover);
  color: #ffffff;
}

.pill-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  list-style: none;
  margin: 2rem 0 0;
  padding: 0;
}

.pill-list li {
  padding: 0.38rem 0.7rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface-subtle);
  color: var(--muted);
  font-size: 0.88rem;
  font-weight: 650;
}

.section {
  padding-block: 1.5rem 4rem;
}

.section-heading {
  max-width: 42rem;
  margin-bottom: 1.6rem;
}

.section-heading p,
.card p,
.muted {
  color: var(--muted);
}

.game-grid,
.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

.card {
  min-width: 0;
  padding: 1.25rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  background: var(--surface);
  overflow-wrap: break-word;
}

.game-card {
  border-width: 2px;
}

.game-card.digit-span {
  border-color: var(--digit-span);
}

.game-card.n-back {
  border-color: var(--n-back);
}

.game-card.percentage {
  border-color: var(--percentage);
}

.game-card.planning {
  border-color: var(--planning);
}

.game-card.probability {
  border-color: var(--probability);
}

.game-card.magnitude {
  border-color: var(--magnitude);
}

.game-symbol {
  display: inline-grid;
  min-width: 3rem;
  min-height: 3rem;
  padding: 0.3rem 0.5rem;
  margin-bottom: 1rem;
  place-items: center;
  border: 2px solid currentColor;
  border-radius: 10px;
  font-size: 1.35rem;
  font-weight: 800;
  line-height: 1;
}

.digit-span .game-symbol {
  color: var(--digit-span);
}

.n-back .game-symbol {
  color: var(--n-back);
}

.percentage .game-symbol {
  color: var(--percentage);
}

.planning .game-symbol {
  color: var(--planning);
}

.probability .game-symbol {
  color: var(--probability);
}

.magnitude .game-symbol {
  color: var(--magnitude);
}

.callout {
  padding: 1.25rem;
  border-left: 4px solid var(--interactive);
  border-radius: 0 var(--radius-card) var(--radius-card) 0;
  background: var(--surface-subtle);
}

.callout > :last-child,
.card > :last-child,
.prose-section > :last-child {
  margin-bottom: 0;
}

.page-intro {
  padding-block: clamp(2.5rem, 7vw, 5rem) 2rem;
}

.breadcrumbs {
  margin: 0 0 1rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.prose-section {
  margin-block: 2rem;
  padding: clamp(1rem, 4vw, 1.6rem);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  background: var(--surface);
}

.prose-section ul,
.prose-section ol {
  padding-left: 1.4rem;
}

.prose-section h3 {
  margin-top: 1.75rem;
}

.prose-section h2 + h3 {
  margin-top: 1.25rem;
}

.meta-list {
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: 0.45rem 1rem;
  margin: 1.5rem 0;
}

.meta-list dt {
  font-weight: 750;
}

.meta-list dd {
  margin: 0;
  color: var(--muted);
}

.meta-list time {
  font-variant-numeric: tabular-nums;
}

.contact-address {
  overflow-wrap: anywhere;
  font-style: normal;
}

.site-footer {
  margin-top: 3rem;
  border-top: 1px solid var(--border);
}

.footer-inner {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 2rem 3rem;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.language-choice {
  display: grid;
  width: min(100% - 2rem, 42rem);
  min-height: 100vh;
  margin-inline: auto;
  place-content: center;
  gap: 1.5rem;
  padding-block: 3rem;
  text-align: center;
}

.language-choice .brand-mark {
  width: 5rem;
  height: 5rem;
  margin-inline: auto;
}

.language-choice h1 {
  margin-bottom: 0.25rem;
}

.language-actions {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
}

@media (max-width: 48rem) {
  .nav {
    align-items: flex-start;
    flex-direction: column;
    padding-block: 0.75rem;
  }

  .nav-links {
    width: 100%;
    justify-content: flex-start;
    flex-wrap: wrap;
    overflow-x: visible;
  }

  .game-grid,
  .feature-grid {
    grid-template-columns: 1fr;
  }

  .section {
    padding-block: var(--space-silver-md) var(--space-silver-xl);
  }

  .footer-inner {
    flex-direction: column;
  }
}

@media (max-width: 32rem) {
  .language-actions {
    grid-template-columns: 1fr;
  }

  .meta-list {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }

  .meta-list dt:not(:first-of-type) {
    margin-top: var(--space-silver-sm);
  }

  .meta-list dd {
    min-width: 0;
    overflow-wrap: anywhere;
  }
}

@media (min-width: 64rem) {
  .hero {
    grid-template-areas: "content visual";
    grid-template-columns: minmax(0, 1.618fr) minmax(18rem, 1fr);
    gap: clamp(2rem, 3.4vw, 3.5rem);
    margin-block: 2rem 3.5rem;
    padding: clamp(3rem, 5vw, 4.5rem) clamp(2.5rem, 4.5vw, 4rem);
  }

  .hero h1 {
    font-size: clamp(2.65rem, 4.2vw, 3.5rem);
    line-height: 1.14;
  }

  .hero-visual {
    width: 100%;
  }
}

@media (min-width: 48.0625rem) {
  .game-grid .game-card:nth-child(5):last-child {
    grid-column: 1 / -1;
    width: calc((100% - 1rem) / 2);
    justify-self: center;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #071219;
    --surface: #0e1d26;
    --surface-subtle: #142731;
    --text: #f2f7f9;
    --muted: #c8d4da;
    --border: #36505d;
    --interactive: #66b3ff;
    --interactive-hover: #a3d3ff;
    --primary: #0b6cab;
    --primary-hover: #1686ce;
    --digit-span: #51e8ff;
    --n-back: #a78bfa;
    --percentage: #5ea7ff;
    --planning: #ffb45c;
    --probability: #ff8bc2;
    --magnitude: #5ee2b6;
    --hero-glow-one: rgb(81 232 255 / 12%);
    --hero-glow-two: rgb(167 139 250 / 12%);
    --shadow: 0 14px 44px rgb(0 0 0 / 22%);
  }
}

@media (prefers-contrast: more) {
  :root {
    --border: currentColor;
    --shadow: none;
  }

  .card,
  .hero,
  .button {
    border-width: 2px;
  }
}

@media (forced-colors: active) {
  .hero,
  .card,
  .button,
  .pill-list li,
  .prose-section {
    border: 1px solid CanvasText;
  }

  .game-symbol {
    color: CanvasText;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}