:root {
  color-scheme: light;
  --bg: #ffffff;
  --surface: #ffffff;
  --surface-soft: #f7f7f7;
  --ink: #191815;
  --muted: #666157;
  --quiet: #9a9488;
  --line: #e7e7e7;
  --accent: #1d5f5a;
  --accent-soft: #dceae5;
  --gold: #a77c31;
  --max: 1120px;
  --measure: 720px;
  font-family: "Hiragino Mincho ProN", "Yu Mincho", "YuMincho", "Noto Serif JP", Georgia, serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: #ffffff;
  color: var(--ink);
  font-size: 16px;
  line-height: 1.9;
  letter-spacing: 0;
}

a {
  color: inherit;
  text-decoration: none;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid rgba(231, 231, 231, 0.86);
  background: rgba(255, 255, 255, 0.86);
  backdrop-filter: blur(18px);
}

.nav {
  width: min(var(--max), calc(100% - 40px));
  min-height: 72px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  font-size: 1.06rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  color: var(--muted);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.88rem;
}

.nav-links a {
  padding: 8px 12px;
  border-radius: 999px;
}

.nav-links a:hover,
.nav-links a[aria-current="page"] {
  color: var(--ink);
  background: rgba(247, 247, 247, 0.9);
}

main {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
}

.hero {
  position: relative;
  min-height: clamp(310px, 44vh, 480px);
  display: flex;
  align-items: center;
  overflow: hidden;
  padding: clamp(52px, 8vw, 100px) 0 clamp(44px, 6vw, 78px);
  isolation: isolate;
}

.hero::before,
.hero::after {
  content: "";
  position: absolute;
  pointer-events: none;
  z-index: -1;
}

.hero::before {
  inset: 20px 0 36px;
  background:
    linear-gradient(90deg, rgba(29, 95, 90, 0.03), transparent 72%),
    linear-gradient(rgba(25, 24, 21, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(25, 24, 21, 0.04) 1px, transparent 1px);
  background-size: auto, 46px 46px, 46px 46px;
  mask-image: linear-gradient(90deg, transparent, black 8%, black 86%, transparent);
}

.hero::after {
  inset: clamp(-18px, -2vw, -6px) 0 auto auto;
  width: min(76vw, 1020px);
  height: min(36vw, 390px);
  background: url("assets/wavepacket.png") center / contain no-repeat;
  opacity: 0.66;
  transform: translateX(17%);
}

.hero > div {
  position: relative;
  max-width: 880px;
}

.eyebrow {
  margin: 0 0 18px;
  color: var(--accent);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1 {
  max-width: 820px;
  margin: 0;
  font-size: clamp(3.8rem, 10vw, 8.6rem);
  line-height: 0.92;
  letter-spacing: 0;
}

.lead {
  max-width: 620px;
  margin: 22px 0 0;
  color: var(--muted);
  font-size: clamp(1rem, 1.6vw, 1.18rem);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 34px;
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
}

.button {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--ink);
  border-radius: 999px;
  padding: 10px 18px;
  font-size: 0.9rem;
  transition: transform 180ms ease, background 180ms ease, color 180ms ease;
}

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

.button:hover {
  transform: translateY(-2px);
}

.small-index {
  position: relative;
  display: grid;
  gap: 10px;
  margin-top: 52px;
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.86rem;
  color: var(--muted);
}

.small-index span {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  border-bottom: 1px solid rgba(231, 231, 231, 0.86);
  padding-bottom: 10px;
}

.section {
  padding: clamp(58px, 8vw, 104px) 0;
}

.section-head {
  display: grid;
  grid-template-columns: minmax(160px, 0.34fr) minmax(0, 0.66fr);
  gap: clamp(24px, 6vw, 76px);
  align-items: start;
  margin-bottom: 36px;
}

.section h2 {
  margin: 0;
  font-size: clamp(1.9rem, 4vw, 3.4rem);
  line-height: 1.1;
}

.section-head p {
  max-width: 620px;
  margin: 8px 0 0;
  color: var(--muted);
}

.category-list,
.article-list,
.term-list {
  display: grid;
}

.article-row,
.term-row {
  display: grid;
  grid-template-columns: minmax(160px, 0.32fr) minmax(0, 1fr) auto;
  gap: 24px;
  align-items: baseline;
  min-height: 86px;
  border-bottom: 1px solid var(--line);
  padding: 20px 0;
  transition: padding-left 180ms ease, color 180ms ease;
}

.article-row {
  grid-template-columns: minmax(160px, 0.28fr) minmax(0, 1fr);
}

.category-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 24px;
  align-items: baseline;
  min-height: 86px;
  border-bottom: 1px solid var(--line);
  padding: 22px 0;
  transition: padding-left 180ms ease, color 180ms ease;
}

div.category-row {
  color: var(--ink);
}

.category-row:hover,
.article-row:hover,
.term-row:hover {
  padding-left: 10px;
  color: var(--accent);
}

.meta,
.count,
.tagline {
  color: var(--muted);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.86rem;
}

.row-title {
  font-size: clamp(1.16rem, 2vw, 1.45rem);
  line-height: 1.45;
}

.pill-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
}

.pill {
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 4px 10px;
  color: var(--muted);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.78rem;
}

.page-title {
  max-width: var(--measure);
  padding: clamp(62px, 10vw, 112px) 0 clamp(38px, 7vw, 76px);
}

.page-title h1 {
  font-size: clamp(2.7rem, 7vw, 6.8rem);
}

.page-title p {
  margin: 24px 0 0;
  color: var(--muted);
  font-size: 1.08rem;
}

.content-grid {
  display: grid;
  grid-template-columns: minmax(180px, 0.34fr) minmax(0, 1fr);
  gap: clamp(28px, 6vw, 80px);
  padding-bottom: 96px;
}

.content-grid.compact-index {
  grid-template-columns: minmax(0, 1fr);
  gap: 22px;
}

.side-label {
  color: var(--quiet);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.compact-index .side-label {
  padding-bottom: 0;
}

.prose {
  max-width: var(--measure);
  font-size: 1.04rem;
}

.prose h2 {
  margin: 44px 0 12px;
  font-size: 1.55rem;
  line-height: 1.35;
}

.prose p {
  margin: 0 0 18px;
}

.note-box {
  margin: 34px 0;
  border-left: 2px solid var(--accent);
  padding: 8px 0 8px 22px;
  color: var(--muted);
}

.article-shell {
  width: min(860px, 100%);
  margin: 0 auto;
  padding: clamp(56px, 8vw, 92px) 0 96px;
}

.article-hero {
  margin-bottom: 48px;
}

.article-hero h1 {
  max-width: 100%;
  font-size: 2.3rem;
  line-height: 1.14;
}

.article-body {
  max-width: var(--measure);
  margin: 0 auto;
  font-size: 1.05rem;
  line-height: 2;
}

.article-body h2 {
  margin: 58px 0 18px;
  font-size: clamp(1.55rem, 3vw, 2.2rem);
  line-height: 1.35;
}

.article-body h3 {
  margin: 36px 0 12px;
  font-size: 1.26rem;
  line-height: 1.45;
}

.article-body p {
  margin: 0 0 22px;
}

.article-body blockquote {
  margin: 30px 0;
  border-left: 2px solid var(--accent);
  padding: 8px 0 8px 22px;
  color: var(--muted);
}

.article-body ul,
.article-body ol {
  margin: 0 0 24px;
  padding-left: 1.45rem;
}

.article-body li {
  margin: 0 0 8px;
}

.article-body a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 0.18em;
}

.article-body .math-block {
  margin: 26px 0;
  overflow-x: auto;
  padding: 8px 0;
  color: var(--ink);
}

.article-body mjx-container {
  overflow-x: auto;
  overflow-y: visible;
  max-width: 100%;
}

.article-body .math-block mjx-container[display="true"] {
  margin: 0.35em 0 !important;
}

.note-figure {
  margin: 38px auto;
}

.note-figure img,
.article-body figure img {
  display: block;
  width: min(100%, 720px);
  height: auto;
  margin: 0 auto;
}

.note-figure figcaption,
.article-body figcaption {
  margin-top: 10px;
  color: var(--quiet);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.82rem;
  line-height: 1.7;
  text-align: center;
}

.embed-card {
  margin: 34px 0;
  padding: 8px 0;
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
}

.embed-card a {
  color: var(--ink);
  text-decoration: none;
}

.embed-card a::after {
  content: " ->";
  color: var(--quiet);
}

.article-pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
  max-width: var(--measure);
  margin: 72px auto 0;
  border-top: 1px solid var(--line);
  padding-top: 24px;
}

.article-pager a {
  display: block;
  color: var(--ink);
}

.article-pager a:last-child {
  text-align: right;
}

.article-pager span {
  display: block;
  margin-bottom: 6px;
  color: var(--quiet);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.78rem;
}

.site-footer {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
  border-top: 1px solid var(--line);
  padding: 28px 0 42px;
  color: var(--quiet);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  font-size: 0.82rem;
}

@media (max-width: 820px) {
  .section-head,
  .content-grid {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: 252px;
    padding: 42px 0 40px;
  }

  .hero::before {
    inset: 12px 0 24px;
    background-size: auto, 34px 34px, 34px 34px;
    mask-image: linear-gradient(90deg, transparent, black 2%, black 94%, transparent);
  }

  .hero::after {
    top: -4px;
    width: 112vw;
    height: 250px;
    opacity: 0.38;
    transform: translateX(42%);
  }

  .article-row,
  .term-row {
    grid-template-columns: 1fr;
    gap: 6px;
    min-height: 0;
  }

  .category-row {
    grid-template-columns: 1fr;
    gap: 4px;
    min-height: 0;
  }

  .article-pager {
    grid-template-columns: 1fr;
  }

  .article-pager a:last-child {
    text-align: left;
  }
}

@media (max-width: 640px) {
  .nav {
    min-height: auto;
    padding: 16px 0;
    align-items: flex-start;
    flex-direction: column;
  }

  .nav-links {
    width: 100%;
    overflow-x: auto;
    padding-bottom: 4px;
  }

  .article-hero h1 {
    font-size: 2rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition: none !important;
  }
}