@font-face {
  font-family: "Shippori Mincho";
  src: url("/assets/riichi-orbit-v5/fonts/shippori-mincho-500-subset.woff2") format("woff2");
  font-style: normal;
  font-weight: 500;
  font-display: swap;
}

@font-face {
  font-family: "Noto Sans JP";
  src: url("/assets/riichi-orbit-v5/fonts/noto-sans-jp-subset.woff2") format("woff2");
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
}

:root {
  color-scheme: dark;
  --void: #020308;
  --surface: #060a12;
  --white: #f4f7fb;
  --silver: #9aa4b2;
  --dim: #687282;
  --cyan: #8ce7f2;
  --indigo: #5c66ff;
  --line: rgba(244, 247, 251, 0.13);
  --line-bright: rgba(244, 247, 251, 0.3);
  --page-pad: clamp(24px, 5vw, 80px);
  --content-width: 1440px;
  --header-height: 68px;
  --ease-out: cubic-bezier(0.2, 0.85, 0.2, 1);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  overflow-x: clip;
  background: var(--void);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  overflow-x: clip;
  background:
    radial-gradient(circle at 78% 5%, rgba(92, 102, 255, 0.1), transparent 30rem),
    var(--void);
  color: var(--white);
  font-family: "Noto Sans JP", "Hiragino Kaku Gothic ProN", "Yu Gothic", sans-serif;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

a {
  color: inherit;
}

h1,
h2,
p,
figure,
ol,
ul,
dl,
dd {
  margin: 0;
}

ol,
ul {
  padding: 0;
  list-style: none;
}

h1,
h2 {
  font-family: "Shippori Mincho", "Yu Mincho", "Hiragino Mincho ProN", serif;
  font-weight: 500;
  letter-spacing: -0.03em;
  text-wrap: balance;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 10px;
  left: 10px;
  padding: 10px 14px;
  background: var(--white);
  color: var(--void);
  font-weight: 700;
  transform: translateY(-180%);
}

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

.section-shell,
.ai-page-hero-shell {
  width: min(100%, var(--content-width));
  margin-inline: auto;
  padding-inline: var(--page-pad);
}

.ai-site-header {
  position: sticky;
  z-index: 30;
  top: 0;
  display: grid;
  min-height: var(--header-height);
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding: 9px var(--page-pad);
  border-bottom: 1px solid var(--line);
  background: rgba(2, 3, 8, 0.88);
  backdrop-filter: blur(18px);
}

.ai-site-brand {
  display: inline-flex;
  width: max-content;
  align-items: center;
  gap: 12px;
  font-family: Inter, Helvetica, Arial, sans-serif;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.26em;
  text-decoration: none;
}

.ai-site-brand img {
  width: 40px;
  height: 40px;
  border-radius: 20%;
}

.ai-site-header nav {
  display: flex;
  gap: clamp(22px, 3vw, 42px);
}

.ai-site-header nav a,
.ai-header-back {
  min-height: 44px;
  align-content: center;
  color: var(--silver);
  font-size: 11px;
  text-decoration: none;
  transition: color 180ms ease;
}

.ai-site-header nav a:hover,
.ai-site-header nav a:focus-visible,
.ai-header-back:hover,
.ai-header-back:focus-visible {
  color: var(--white);
}

.ai-header-back {
  justify-self: end;
  padding-inline: 15px;
  border: 1px solid var(--line-bright);
}

.reading-progress {
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 100%;
  height: 1px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: left;
}

.ai-page-hero {
  border-bottom: 1px solid var(--line);
}

.ai-page-hero-shell {
  display: grid;
  min-height: calc(100svh - var(--header-height));
  grid-template-columns: minmax(360px, 0.84fr) minmax(0, 1.16fr);
  align-items: center;
  gap: clamp(54px, 7vw, 118px);
  padding-top: clamp(75px, 8vh, 110px);
  padding-bottom: clamp(75px, 8vh, 110px);
}

.ai-page-hero-copy {
  max-width: 620px;
}

.orbit-ai-lockup {
  display: flex;
  align-items: center;
  gap: 14px;
}

.orbit-ai-lockup > img {
  width: 62px;
  height: 62px;
  object-fit: contain;
}

.orbit-ai-lockup > div {
  display: grid;
  gap: 7px;
}

.orbit-ai-lockup p {
  font-family: Inter, Helvetica, Arial, sans-serif;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.18em;
}

.orbit-ai-lockup small {
  color: var(--dim);
  font-family: Inter, Helvetica, Arial, sans-serif;
  font-size: 8px;
  font-weight: 700;
  letter-spacing: 0.2em;
}

.ai-page-hero h1 {
  margin-top: 41px;
  font-size: clamp(50px, 4.4vw, 64px);
  line-height: 1.34;
}

.ai-page-hero-copy > p {
  max-width: 560px;
  margin-top: 28px;
  color: var(--silver);
  font-size: clamp(14px, 1.2vw, 17px);
  line-height: 2;
}

.hero-scroll-link {
  display: inline-flex;
  min-height: 56px;
  align-items: center;
  gap: 46px;
  margin-top: 36px;
  padding: 0 19px 0 23px;
  border: 1px solid var(--line-bright);
  font-size: 13px;
  text-decoration: none;
  transition: border-color 180ms ease, background-color 180ms ease, transform 180ms var(--ease-out);
}

.hero-scroll-link svg {
  width: 20px;
  height: 20px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 1.4;
}

.hero-scroll-link:hover,
.hero-scroll-link:focus-visible {
  border-color: var(--cyan);
  background: rgba(140, 231, 242, 0.06);
  transform: translateY(-3px);
}

.hero-scroll-link:focus-visible,
.ai-header-back:focus-visible,
.ai-site-header nav a:focus-visible,
.ai-site-brand:focus-visible,
.ai-page-end a:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 4px;
}

.ai-page-hero-figure {
  min-width: 0;
}

.ai-page-hero-figure img,
.chapter-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  border: 1px solid rgba(140, 231, 242, 0.17);
  background: #03050a;
  object-fit: cover;
}

.ai-page-hero-figure figcaption,
.chapter-figure figcaption {
  margin-top: 13px;
  color: var(--dim);
  font-size: 9px;
  line-height: 1.75;
}

.ai-overview {
  padding-top: clamp(130px, 14vw, 210px);
  padding-bottom: clamp(125px, 13vw, 190px);
}

.overview-heading {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  align-items: end;
  gap: 60px;
}

.overview-heading h2 {
  font-size: clamp(44px, 4.6vw, 68px);
  line-height: 1.35;
}

.overview-heading p {
  max-width: 620px;
  color: var(--silver);
  font-size: 15px;
  line-height: 2;
}

.overview-flow {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  margin-top: clamp(65px, 7vw, 100px);
  border-block: 1px solid var(--line);
}

.overview-flow li {
  position: relative;
  display: grid;
  min-height: 148px;
  align-content: center;
  gap: 9px;
  padding: 22px clamp(14px, 2vw, 28px);
  border-left: 1px solid var(--line);
}

.overview-flow li:last-child {
  border-right: 1px solid var(--line);
}

.overview-flow li:not(:last-child)::after {
  position: absolute;
  z-index: 2;
  top: calc(50% - 4px);
  right: -4px;
  width: 7px;
  height: 7px;
  border-top: 1px solid var(--cyan);
  border-right: 1px solid var(--cyan);
  background: var(--void);
  content: "";
  transform: rotate(45deg);
}

.overview-flow span,
.chapter-index,
.ai-principles li > span {
  color: var(--cyan);
  font-family: Inter, Helvetica, Arial, sans-serif;
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.18em;
}

.overview-flow strong {
  font-family: "Shippori Mincho", "Yu Mincho", "Hiragino Mincho ProN", serif;
  font-size: clamp(20px, 1.8vw, 28px);
  font-weight: 500;
}

.overview-flow small {
  color: var(--dim);
  font-size: 10px;
}

.overview-facts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 28px;
}

.overview-facts li {
  display: flex;
  min-height: 104px;
  align-items: center;
  justify-content: center;
  gap: clamp(18px, 2.5vw, 38px);
  border-bottom: 1px solid var(--line);
}

.overview-facts strong {
  font-family: "Shippori Mincho", "Yu Mincho", "Hiragino Mincho ProN", serif;
  font-size: clamp(38px, 4vw, 58px);
  font-weight: 500;
}

.overview-facts span {
  color: var(--silver);
  font-size: 11px;
}

.ai-chapter {
  display: grid;
  min-height: min(940px, 100svh);
  grid-template-columns: minmax(0, 1.08fr) minmax(330px, 0.92fr);
  align-items: center;
  gap: clamp(60px, 8vw, 130px);
  padding-top: clamp(110px, 11vw, 165px);
  padding-bottom: clamp(110px, 11vw, 165px);
  border-top: 1px solid var(--line);
}

.ai-chapter-reverse {
  grid-template-columns: minmax(330px, 0.92fr) minmax(0, 1.08fr);
}

.ai-chapter-reverse .chapter-figure {
  order: 2;
}

.ai-chapter-reverse .chapter-copy {
  order: 1;
}

.chapter-figure {
  min-width: 0;
}

.chapter-copy {
  max-width: 590px;
}

.chapter-index {
  display: flex;
  align-items: center;
  gap: 14px;
}

.chapter-index span {
  min-width: 35px;
  padding-bottom: 4px;
  border-bottom: 1px solid var(--cyan);
  color: var(--white);
  letter-spacing: 0.08em;
}

.chapter-copy h2 {
  margin-top: 26px;
  font-size: clamp(40px, 4.1vw, 62px);
  line-height: 1.38;
}

.chapter-copy > p:not(.chapter-index) {
  margin-top: 25px;
  color: var(--silver);
  font-size: clamp(13px, 1.1vw, 16px);
  line-height: 2;
}

.chapter-copy > p:not(.chapter-index) + p {
  margin-top: 15px;
}

.chapter-facts {
  margin-top: 34px;
  border-top: 1px solid var(--line-bright);
}

.chapter-facts > div {
  display: grid;
  min-height: 56px;
  grid-template-columns: 90px 1fr;
  align-items: center;
  border-bottom: 1px solid var(--line);
}

.chapter-facts dt {
  color: var(--cyan);
  font-size: 10px;
}

.chapter-facts dd {
  color: var(--silver);
  font-size: 11px;
  line-height: 1.7;
}

.validation-chapter {
  background: linear-gradient(140deg, rgba(8, 12, 21, 0.5), transparent 55%);
}

.explain-chapter {
  background:
    radial-gradient(circle at 25% 50%, rgba(140, 231, 242, 0.06), transparent 26rem),
    linear-gradient(145deg, rgba(8, 12, 21, 0.58), transparent 58%);
}

.ai-principles {
  padding-top: clamp(120px, 13vw, 190px);
  padding-bottom: clamp(130px, 14vw, 210px);
  border-top: 1px solid var(--line);
}

.ai-principles h2 {
  font-size: clamp(42px, 4.6vw, 68px);
  line-height: 1.35;
}

.ai-principles ul {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 72px;
  border-block: 1px solid var(--line);
}

.ai-principles li {
  min-height: 220px;
  padding: 38px clamp(24px, 3vw, 44px);
  border-left: 1px solid var(--line);
}

.ai-principles li:last-child {
  border-right: 1px solid var(--line);
}

.ai-principles li > span {
  color: var(--dim);
}

.ai-principles strong {
  display: block;
  margin-top: 25px;
  font-family: "Shippori Mincho", "Yu Mincho", "Hiragino Mincho ProN", serif;
  font-size: clamp(22px, 2.2vw, 32px);
  font-weight: 500;
  line-height: 1.45;
}

.ai-principles li p {
  margin-top: 17px;
  color: var(--silver);
  font-size: 12px;
  line-height: 1.85;
}

.ai-page-end {
  display: grid;
  min-height: 700px;
  place-items: center;
  align-content: center;
  padding: 100px var(--page-pad);
  border-top: 1px solid var(--line);
  background:
    radial-gradient(circle, rgba(92, 102, 255, 0.14), transparent 26rem),
    #03050a;
  text-align: center;
}

.ai-page-end img {
  width: 82px;
  height: 82px;
  object-fit: contain;
}

.ai-page-end h2 {
  margin-top: 31px;
  font-size: clamp(42px, 5vw, 72px);
  line-height: 1.38;
}

.ai-page-end a {
  display: inline-flex;
  min-height: 58px;
  align-items: center;
  margin-top: 39px;
  padding-inline: 25px;
  border: 1px solid var(--white);
  background: var(--white);
  color: var(--void);
  font-size: 13px;
  font-weight: 700;
  text-decoration: none;
  transition: background-color 180ms ease, color 180ms ease, transform 180ms var(--ease-out);
}

.ai-page-end a:hover {
  background: transparent;
  color: var(--white);
  transform: translateY(-3px);
}

footer {
  display: flex;
  width: min(100%, var(--content-width));
  min-height: 100px;
  align-items: center;
  justify-content: space-between;
  margin-inline: auto;
  padding: 24px var(--page-pad);
  color: var(--dim);
  font-size: 10px;
}

footer a {
  color: var(--silver);
  font-family: Inter, Helvetica, Arial, sans-serif;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.22em;
  text-decoration: none;
}

footer p {
  line-height: 1.7;
  text-align: right;
}

[data-reveal] {
  opacity: 1;
  transform: none;
}

.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 800ms ease, transform 900ms var(--ease-out);
}

.has-js [data-reveal].is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 1050px) {
  .ai-site-header nav {
    gap: 18px;
  }

  .ai-page-hero-shell {
    grid-template-columns: minmax(320px, 0.9fr) minmax(0, 1.1fr);
    gap: 50px;
  }

  .ai-page-hero h1 {
    font-size: 44px;
  }

  .ai-chapter,
  .ai-chapter-reverse {
    grid-template-columns: minmax(0, 1fr) minmax(310px, 0.9fr);
    gap: 55px;
  }

  .ai-chapter-reverse {
    grid-template-columns: minmax(310px, 0.9fr) minmax(0, 1fr);
  }
}

@media (max-width: 820px) {
  :root {
    --page-pad: 20px;
    --header-height: 62px;
  }

  .ai-site-header {
    grid-template-columns: 1fr auto;
  }

  .ai-site-header nav {
    display: none;
  }

  .ai-site-brand {
    font-size: 9px;
    letter-spacing: 0.2em;
  }

  .ai-site-brand img {
    width: 36px;
    height: 36px;
  }

  .ai-header-back {
    padding-inline: 12px;
    font-size: 10px;
  }

  .ai-page-hero-shell {
    display: flex;
    min-height: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding-top: 70px;
    padding-bottom: 86px;
  }

  .orbit-ai-lockup {
    gap: 11px;
  }

  .orbit-ai-lockup > img {
    width: 50px;
    height: 50px;
  }

  .orbit-ai-lockup p {
    font-size: 14px;
  }

  .orbit-ai-lockup small {
    font-size: 6px;
  }

  .ai-page-hero h1 {
    margin-top: 31px;
    font-size: clamp(36px, 10vw, 48px);
    line-height: 1.38;
  }

  .ai-page-hero-copy > p {
    margin-top: 22px;
    font-size: 14px;
    line-height: 1.95;
  }

  .hero-scroll-link {
    width: 100%;
    justify-content: space-between;
    margin-top: 29px;
  }

  .ai-page-hero-figure {
    margin-top: 52px;
  }

  .ai-page-hero-figure img {
    width: calc(100% + var(--page-pad) * 2);
    max-width: none;
    margin-left: calc(var(--page-pad) * -1);
    border-right: 0;
    border-left: 0;
  }

  .ai-page-hero-figure figcaption,
  .chapter-figure figcaption {
    font-size: 10px;
  }

  .ai-overview {
    padding-top: 100px;
    padding-bottom: 100px;
  }

  .overview-heading {
    display: block;
  }

  .overview-heading h2 {
    font-size: clamp(32px, 8.6vw, 44px);
  }

  .overview-heading p {
    margin-top: 22px;
    font-size: 13px;
  }

  .overview-flow {
    grid-template-columns: 1fr;
    margin-top: 52px;
  }

  .overview-flow li {
    min-height: 82px;
    grid-template-columns: 42px 1fr auto;
    align-items: center;
    gap: 12px;
    padding: 15px 17px;
    border-right: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
  }

  .overview-flow li:not(:last-child)::after {
    top: auto;
    right: auto;
    bottom: -4px;
    left: 18px;
    transform: rotate(135deg);
  }

  .overview-flow strong {
    font-size: 22px;
  }

  .overview-facts {
    grid-template-columns: 1fr;
    margin-top: 24px;
  }

  .overview-facts li {
    min-height: 78px;
    justify-content: flex-start;
    padding-inline: 18px;
    border-left: 1px solid var(--line);
    border-right: 1px solid var(--line);
  }

  .overview-facts strong {
    min-width: 66px;
    font-size: 42px;
  }

  .ai-chapter,
  .ai-chapter-reverse {
    display: flex;
    min-height: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding-top: 88px;
    padding-bottom: 94px;
  }

  .ai-chapter .chapter-figure,
  .ai-chapter-reverse .chapter-figure {
    order: 1;
  }

  .ai-chapter .chapter-copy,
  .ai-chapter-reverse .chapter-copy {
    order: 2;
  }

  .chapter-figure {
    width: calc(100% + var(--page-pad) * 2);
    margin-left: calc(var(--page-pad) * -1);
  }

  .chapter-figure img {
    border-right: 0;
    border-left: 0;
  }

  .chapter-figure figcaption {
    padding-inline: var(--page-pad);
  }

  .chapter-copy {
    max-width: none;
    margin-top: 49px;
  }

  .chapter-copy h2 {
    margin-top: 23px;
    font-size: clamp(30px, 8.2vw, 40px);
    line-height: 1.42;
  }

  .chapter-copy > p:not(.chapter-index) {
    margin-top: 21px;
    font-size: 14px;
    line-height: 1.95;
  }

  .chapter-facts {
    margin-top: 29px;
  }

  .chapter-facts > div {
    min-height: 62px;
    grid-template-columns: 74px 1fr;
  }

  .chapter-facts dd {
    font-size: 11px;
  }

  .ai-principles {
    padding-top: 100px;
    padding-bottom: 110px;
  }

  .ai-principles h2 {
    font-size: clamp(34px, 9vw, 46px);
  }

  .ai-principles ul {
    grid-template-columns: 1fr;
    margin-top: 50px;
  }

  .ai-principles li,
  .ai-principles li:last-child {
    min-height: 0;
    padding: 29px 22px 32px;
    border-right: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
  }

  .ai-principles strong {
    margin-top: 17px;
    font-size: 25px;
  }

  .ai-page-end {
    min-height: 620px;
    padding-block: 90px;
  }

  .ai-page-end img {
    width: 70px;
    height: 70px;
  }

  .ai-page-end h2 {
    font-size: clamp(34px, 9vw, 46px);
  }

  .ai-page-end a {
    width: 100%;
    justify-content: center;
  }

  footer {
    align-items: flex-start;
    flex-direction: column;
    gap: 12px;
  }

  footer p {
    text-align: left;
  }

}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }

  .has-js [data-reveal] {
    opacity: 1;
    transform: none;
  }
}