:root {
  --paper: #f2f0e9;
  --paper-2: #e8e5dc;
  --ink: #151a18;
  --muted: #626963;
  --line: #c8c8be;
  --white: #fffef9;
  --dark: #10241d;
  --dark-2: #1b3028;
  --acid: #d7f743;
  --red: #ef5a3c;
  --blue: #356ca8;
  --orange: #e76d3f;
  --purple: #7158a2;
  --radius: 24px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 76px;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Hiragino Sans", "Yu Gothic", "YuGothic", "Noto Sans JP", sans-serif;
  font-feature-settings: "palt";
  line-height: 1.8;
}

a { color: inherit; }
button { font: inherit; }
code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }
em { font-style: normal; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; }
.skip-link { position: fixed; z-index: 100; top: 10px; left: 10px; padding: 10px 14px; transform: translateY(-160%); color: white; background: var(--ink); }
.skip-link:focus { transform: none; }

.site-header {
  position: sticky;
  z-index: 40;
  top: 0;
  display: grid;
  min-height: 72px;
  padding: 0 4vw;
  border-bottom: 1px solid rgba(21, 26, 24, 0.16);
  background: rgba(242, 240, 233, 0.92);
  backdrop-filter: blur(16px);
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
}

.brand {
  display: inline-flex;
  width: fit-content;
  align-items: center;
  gap: 11px;
  font-weight: 900;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 39px;
  height: 39px;
  place-items: center;
  color: var(--dark);
  background: var(--acid);
  font-family: ui-monospace, SFMono-Regular, monospace;
  font-size: 10px;
  font-weight: 950;
  letter-spacing: -0.05em;
}

.brand-name { font-size: 14px; letter-spacing: 0.02em; }

.desktop-nav { display: flex; gap: 32px; }
.desktop-nav a { color: #4f5752; font-size: 11px; font-weight: 800; text-decoration: none; }
.desktop-nav a:hover, .desktop-nav a:focus-visible { color: var(--red); }

.header-cta {
  justify-self: end;
  padding: 9px 15px;
  border: 1px solid var(--ink);
  font-family: ui-monospace, monospace;
  font-size: 10px;
  font-weight: 900;
  letter-spacing: 0.06em;
  text-decoration: none;
}
.header-cta span { margin-left: 7px; }

.menu-button, .mobile-menu { display: none; }

.hero {
  display: grid;
  min-height: calc(100vh - 72px);
  max-width: 1440px;
  margin: 0 auto;
  padding: clamp(78px, 9vw, 132px) 5vw clamp(84px, 10vw, 140px);
  grid-template-columns: minmax(0, 1.08fr) minmax(390px, 0.92fr);
  gap: clamp(55px, 8vw, 120px);
  align-items: center;
}

.eyebrow, .section-label {
  display: flex;
  margin: 0 0 24px;
  align-items: center;
  gap: 12px;
  color: #606861;
  font-family: ui-monospace, SFMono-Regular, monospace;
  font-size: 10px;
  font-weight: 900;
  letter-spacing: 0.13em;
}

.eyebrow span, .section-label span {
  padding: 4px 8px;
  color: var(--dark);
  background: var(--acid);
}

.hero h1 {
  max-width: 800px;
  margin: 0;
  font-family: "Yu Mincho", "Hiragino Mincho ProN", Georgia, serif;
  font-size: clamp(45px, 5.5vw, 82px);
  font-weight: 700;
  letter-spacing: -0.065em;
  line-height: 1.2;
}

.hero h1 em { position: relative; color: var(--red); }
.hero h1 em::after {
  position: absolute;
  right: 0;
  bottom: -7px;
  left: 0;
  height: 5px;
  transform: rotate(-1deg);
  background: var(--red);
  content: "";
  opacity: 0.22;
}

.hero-lead {
  margin: 34px 0 16px;
  color: #525b55;
  font-size: clamp(15px, 1.4vw, 18px);
  line-height: 2;
}

.hero-answer {
  max-width: 690px;
  margin: 0;
  padding-left: 18px;
  border-left: 3px solid var(--ink);
  font-size: 14px;
}

.hero-actions { display: flex; margin-top: 34px; gap: 25px; align-items: center; }

.primary-button {
  display: inline-flex;
  min-height: 58px;
  padding: 14px 18px 14px 24px;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  border: 1px solid var(--dark);
  color: white;
  background: var(--dark);
  font-size: 13px;
  font-weight: 900;
  text-decoration: none;
  transition: transform 160ms ease, box-shadow 160ms ease;
}

.primary-button span {
  display: grid;
  width: 27px;
  height: 27px;
  place-items: center;
  color: var(--dark);
  background: var(--acid);
}

.primary-button:hover, .primary-button:focus-visible { transform: translateY(-2px); box-shadow: 7px 7px 0 var(--acid); }

.text-link { font-size: 12px; font-weight: 800; text-underline-offset: 5px; }
.text-link span { margin-left: 7px; }

.hero-visual { position: relative; }
.feed-window {
  overflow: hidden;
  transform: rotate(1.2deg);
  border: 1px solid #8f948e;
  background: var(--white);
  box-shadow: 18px 22px 0 rgba(16, 36, 29, 0.1);
}

.feed-bar {
  display: flex;
  height: 42px;
  padding: 0 15px;
  align-items: center;
  gap: 6px;
  border-bottom: 1px solid var(--line);
  background: #e4e3dc;
}
.feed-bar > span { width: 8px; height: 8px; border: 1px solid #767b76; border-radius: 50%; }
.feed-bar b { margin-left: auto; font-family: ui-monospace, monospace; font-size: 8px; letter-spacing: 0.12em; }

.feed-post { display: grid; padding: 24px; border-bottom: 1px solid var(--line); grid-template-columns: 42px 1fr; gap: 14px; }
.avatar { display: grid; width: 42px; height: 42px; place-items: center; border-radius: 50%; color: white; background: var(--ink); font-family: Georgia, serif; font-size: 18px; }
.feed-post p { margin: 0; font-size: 13px; line-height: 1.7; }
.feed-post .handle { margin-bottom: 5px; color: #7a817b; font-family: ui-monospace, monospace; font-size: 9px; }

.reaction-prompt { display: flex; padding: 11px 24px; align-items: center; gap: 12px; color: white; background: var(--dark); }
.reaction-prompt span { font-size: 10px; font-weight: 900; }
.reaction-prompt i { height: 1px; flex: 1; background: rgba(255,255,255,.25); }

.reply-stack { padding: 14px; }
.reply-stack p {
  display: grid;
  margin: 0;
  padding: 14px 10px;
  border-bottom: 1px solid #dddcd4;
  grid-template-columns: 30px 1fr;
  gap: 3px 10px;
}
.reply-stack p:last-child { border-bottom: 0; }
.reply-stack p > span { grid-row: 1 / 3; color: var(--red); font-family: Georgia, serif; font-size: 15px; font-weight: 700; }
.reply-stack b { font-family: Georgia, serif; font-size: clamp(15px, 1.6vw, 19px); line-height: 1.35; }
.reply-stack small { color: #747a75; font-size: 9px; }

.visual-note {
  position: absolute;
  right: -18px;
  bottom: -32px;
  padding: 13px 16px;
  transform: rotate(-2deg);
  color: white;
  background: var(--red);
  font-size: 10px;
  font-weight: 900;
}
.visual-note span { margin-right: 10px; color: var(--acid); font-family: ui-monospace, monospace; font-size: 8px; }

.concept-strip {
  display: flex;
  overflow: hidden;
  min-height: 64px;
  padding: 0 5vw;
  align-items: center;
  justify-content: space-around;
  gap: 28px;
  color: white;
  background: var(--ink);
  font-family: ui-monospace, monospace;
  font-size: clamp(10px, 1.2vw, 13px);
  font-weight: 900;
  letter-spacing: 0.13em;
  white-space: nowrap;
}
.concept-strip i { color: var(--acid); font-style: normal; }

.problem-section, .phrase-section, .method-section, .curriculum-section {
  padding: 125px max(5vw, calc((100vw - 1180px) / 2));
}

.problem-grid { display: grid; grid-template-columns: 0.88fr 1.12fr; gap: clamp(55px, 8vw, 110px); }
.problem-grid h2, .phrase-heading h2, .method-heading h2, .curriculum-heading h2, .learn-heading h2, .concept-intro h2 {
  margin: 0;
  font-family: "Yu Mincho", "Hiragino Mincho ProN", Georgia, serif;
  font-size: clamp(38px, 5vw, 66px);
  font-weight: 700;
  letter-spacing: -0.055em;
  line-height: 1.28;
}
.problem-grid h2 em, .method-heading h2 em { color: var(--red); }

.problem-copy > p { margin: 0 0 28px; color: #4e5650; font-size: 15px; }
.known-list { margin: 0 0 30px; padding: 0; border-top: 1px solid var(--line); list-style: none; }
.known-list li { display: grid; padding: 18px 0; border-bottom: 1px solid var(--line); grid-template-columns: 105px 1fr; font-weight: 700; }
.known-list span { color: var(--red); font-family: ui-monospace, monospace; font-size: 9px; font-weight: 900; letter-spacing: 0.1em; }
.problem-copy .problem-turn { margin: 0; color: var(--ink); font-size: 16px; line-height: 2; }

.gap-statement {
  display: grid;
  margin-top: 80px;
  padding: 40px 44px;
  border: 1px solid var(--ink);
  background: var(--white);
  grid-template-columns: 95px 0.8fr 1.2fr;
  gap: 30px;
  align-items: center;
}
.gap-statement span { color: var(--red); font-family: ui-monospace, monospace; font-size: 12px; font-weight: 950; }
.gap-statement p { margin: 0; font-family: "Yu Mincho", Georgia, serif; font-size: 18px; font-weight: 700; }
.gap-statement strong { font-size: 15px; line-height: 1.9; }

.concept-section {
  display: grid;
  padding: 130px max(5vw, calc((100vw - 1180px) / 2));
  color: white;
  background: var(--dark);
  grid-template-columns: 0.8fr 1.2fr;
  gap: clamp(60px, 10vw, 140px);
}
.section-label.light { color: #aebdb7; }
.concept-intro h2 { color: white; font-size: clamp(56px, 7vw, 92px); }
.concept-intro h2 em { color: var(--acid); }
.definition-lead { margin: 0; font-family: "Yu Mincho", Georgia, serif; font-size: clamp(21px, 2.5vw, 31px); font-weight: 600; line-height: 1.8; }
.definition-rule { width: 100%; height: 1px; margin: 38px 0; background: rgba(255,255,255,.22); }
.concept-definition > p:last-of-type { margin: 0; color: #d4dfda; font-size: 15px; line-height: 2; }
.serious-note { display: grid; margin-top: 58px; padding: 27px; border: 1px solid rgba(215,247,67,.5); grid-template-columns: 0.9fr 1.1fr; gap: 28px; }
.serious-note > span { color: var(--acid); font-family: ui-monospace, monospace; font-size: 9px; font-weight: 900; letter-spacing: 0.12em; line-height: 1.8; }
.serious-note p { margin: 0; font-size: 14px; }

.phrase-section { background: var(--white); }
.phrase-heading { display: flex; margin-bottom: 52px; align-items: end; justify-content: space-between; gap: 40px; }
.phrase-heading p { max-width: 370px; margin: 0; color: var(--muted); font-size: 14px; }
.phrase-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.phrase-grid article { min-height: 300px; padding: 28px; border: 1px solid var(--line); background: var(--paper); }
.phrase-grid article:nth-child(2) { transform: translateY(22px); color: white; background: var(--dark); }
.phrase-grid article > span { color: var(--red); font-family: ui-monospace, monospace; font-size: 9px; font-weight: 900; letter-spacing: 0.14em; }
.phrase-grid article:nth-child(2) > span { color: var(--acid); }
.phrase-grid h3 { margin: 56px 0 35px; font-family: Georgia, serif; font-size: clamp(24px, 2.8vw, 36px); font-weight: 500; letter-spacing: -0.025em; line-height: 1.25; }
.phrase-grid p { margin: 0; color: var(--muted); font-size: 12px; }
.phrase-grid article:nth-child(2) p { color: #b7c6c0; }

.phrase-heading h2 em { color: var(--red); }

.chunk-system {
  margin-top: 115px;
  padding-top: 70px;
  border-top: 1px solid var(--line);
}

.chunk-system-heading {
  display: grid;
  margin-bottom: 46px;
  grid-template-columns: 0.8fr 1.15fr 1.05fr;
  gap: 38px;
  align-items: start;
}

.chunk-system-heading > span {
  color: var(--red);
  font-family: ui-monospace, SFMono-Regular, monospace;
  font-size: 9px;
  font-weight: 900;
  letter-spacing: 0.13em;
}

.chunk-system-heading h3 {
  margin: 0;
  font-family: "Yu Mincho", "Hiragino Mincho ProN", Georgia, serif;
  font-size: clamp(27px, 3.4vw, 44px);
  line-height: 1.42;
}

.chunk-system-heading p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 2;
}

.learning-loop {
  display: grid;
  margin: 0;
  padding: 0;
  border: 1px solid var(--ink);
  list-style: none;
  grid-template-columns: repeat(3, 1fr);
}

.learning-loop li {
  display: grid;
  min-height: 225px;
  padding: 25px;
  border-right: 1px solid var(--ink);
  grid-template-columns: 38px 1fr;
  gap: 15px;
}

.learning-loop li:last-child { border-right: 0; }
.learning-loop li:nth-child(2) { background: var(--paper-2); }
.learning-loop li:nth-child(3) { color: white; background: var(--dark); }

.loop-no {
  color: var(--red);
  font-family: Georgia, serif;
  font-size: 17px;
  font-weight: 700;
}

.learning-loop b {
  color: var(--red);
  font-family: ui-monospace, monospace;
  font-size: 9px;
  letter-spacing: 0.12em;
}

.learning-loop li:nth-child(3) b,
.learning-loop li:nth-child(3) .loop-no { color: var(--acid); }

.learning-loop h4 {
  margin: 29px 0 10px;
  font-family: "Yu Mincho", Georgia, serif;
  font-size: 19px;
}

.learning-loop p {
  margin: 0;
  color: var(--muted);
  font-size: 11px;
  line-height: 1.8;
}

.learning-loop li:nth-child(3) p { color: #b7c7c1; }

.chunk-demo {
  display: grid;
  margin-top: 16px;
  grid-template-columns: 0.82fr 1.18fr;
  gap: 16px;
}

.repeat-demo,
.integrate-demo {
  padding: 28px;
  border: 1px solid var(--line);
  background: var(--paper);
}

.repeat-demo > span,
.integrate-demo > span {
  color: var(--red);
  font-family: ui-monospace, monospace;
  font-size: 9px;
  font-weight: 900;
  letter-spacing: 0.12em;
}

.repeat-demo p {
  margin: 13px 0 0;
  font-family: Georgia, serif;
  font-size: clamp(18px, 2vw, 24px);
  line-height: 1.35;
}

.repeat-demo p:nth-of-type(n+2) { color: #69706b; }
.repeat-demo b { color: var(--red); }

.repeat-demo small,
.integrate-demo > small {
  display: block;
  margin-top: 22px;
  color: var(--muted);
  font-size: 10px;
  font-weight: 700;
}

.integrated-sentence {
  display: flex;
  margin-top: 21px;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 8px;
  font-family: Georgia, serif;
  font-size: clamp(17px, 1.8vw, 22px);
}

.integrated-sentence > b { padding-top: 15px; white-space: nowrap; }

.chunk-box {
  display: grid;
  padding: 12px;
  border: 2px solid var(--orange);
  border-radius: 10px;
  background: #fff4ed;
  grid-template-columns: auto 1fr;
  gap: 9px;
}

.chunk-box > i {
  color: var(--orange);
  font-family: ui-monospace, monospace;
  font-size: 9px;
  font-style: normal;
  font-weight: 900;
  letter-spacing: 0.08em;
}

.chunk-box p { margin: 0; }

.about-box {
  margin-top: 10px;
  border-color: var(--blue);
  background: #edf5ff;
}

.about-box > i { color: var(--blue); }
.about-box strong { font-weight: 500; }

.method-section { padding-top: 150px; }
.method-heading { display: grid; margin-bottom: 60px; grid-template-columns: 1.2fr 0.8fr; gap: 45px; align-items: end; }
.method-heading .section-label { grid-column: 1 / -1; }
.method-heading > p:last-child { margin: 0; color: var(--muted); font-size: 14px; }
.de-card { display: grid; min-height: 360px; border: 1px solid var(--ink); background: var(--white); grid-template-columns: 0.55fr 0.8fr 0.25fr 1.4fr; align-items: stretch; }
.de-mark { display: grid; place-items: center; color: white; background: var(--red); font-family: "Yu Mincho", Georgia, serif; font-size: clamp(78px, 10vw, 130px); font-weight: 700; }
.de-copy { display: flex; padding: 34px; justify-content: space-between; flex-direction: column; }
.de-copy p { margin: 0; font-family: "Yu Mincho", Georgia, serif; font-size: 22px; font-weight: 700; line-height: 1.7; }
.de-copy span { color: var(--muted); font-size: 10px; font-weight: 800; }
.de-arrow { display: grid; place-items: center; border-right: 1px solid var(--line); border-left: 1px solid var(--line); font-size: 30px; }
.relation-split { display: grid; grid-template-rows: 1fr 1fr; }
.relation-split article { display: flex; padding: 30px; justify-content: center; flex-direction: column; }
.relation-split article:first-child { border-bottom: 1px solid var(--line); }
.relation-split article > span { font-family: ui-monospace, monospace; font-size: 9px; font-weight: 900; letter-spacing: 0.12em; }
.relation-split h3 { margin: 12px 0 0; font-family: Georgia, serif; font-size: clamp(20px, 2.3vw, 30px); font-weight: 500; line-height: 1.35; }
.with-relation span, .with-relation b { color: var(--orange); }
.from-relation span, .from-relation b { color: var(--purple); }

.method-message { display: grid; margin: 52px 0; grid-template-columns: 1fr 1fr; gap: 55px; }
.method-message p { margin: 0; font-size: 15px; line-height: 2; }
.method-message p:last-child { color: var(--muted); }

.lesson-banner {
  display: grid;
  min-height: 128px;
  padding: 25px 32px;
  align-items: center;
  border: 1px solid var(--dark);
  color: white;
  background: var(--dark);
  grid-template-columns: 150px 1fr 50px;
  text-decoration: none;
  transition: transform 160ms ease, box-shadow 160ms ease;
}
.lesson-banner:hover, .lesson-banner:focus-visible { transform: translate(-3px, -3px); box-shadow: 8px 8px 0 var(--acid); }
.lesson-no { color: var(--acid); font-family: ui-monospace, monospace; font-size: 10px; font-weight: 900; letter-spacing: .12em; }
.lesson-title { font-family: "Yu Mincho", Georgia, serif; font-size: clamp(19px, 2.2vw, 28px); font-weight: 700; line-height: 1.5; }
.lesson-arrow { display: grid; width: 42px; height: 42px; place-items: center; color: var(--dark); background: var(--acid); }

.learn-section {
  display: grid;
  padding: 130px max(5vw, calc((100vw - 1180px) / 2));
  color: white;
  background: #1b2723;
  grid-template-columns: 0.82fr 1.18fr;
  gap: clamp(60px, 9vw, 120px);
}
.learn-heading { position: sticky; top: 110px; align-self: start; }
.learn-heading h2 { color: white; }
.learn-list { margin: 0; padding: 0; border-top: 1px solid rgba(255,255,255,.2); list-style: none; }
.learn-list li { display: grid; padding: 22px 0; border-bottom: 1px solid rgba(255,255,255,.2); grid-template-columns: 55px 1fr; gap: 18px; }
.learn-list span { color: var(--acid); font-family: Georgia, serif; font-size: 17px; }
.learn-list p { margin: 0; color: #d7dfdc; font-size: 14px; }
.learn-list strong { color: white; }
.learn-list code { color: var(--acid); }

.curriculum-heading { display: flex; margin-bottom: 55px; align-items: end; justify-content: space-between; gap: 30px; }
.curriculum-heading .section-label { position: absolute; margin-top: -65px; }
.lesson-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 15px; }
.lesson-grid-single { grid-template-columns: minmax(0, 620px); }
.curriculum-heading > p:last-child { max-width: 430px; margin: 0; color: var(--muted); line-height: 1.9; }
.curriculum-card { position: relative; min-height: 385px; padding: 30px; overflow: hidden; border: 1px solid var(--line); background: var(--paper-2); }
a.curriculum-card { text-decoration: none; }
.curriculum-card.current { color: white; background: var(--dark); }
.card-status { font-family: ui-monospace, monospace; font-size: 9px; font-weight: 900; letter-spacing: .13em; }
.current .card-status { color: var(--acid); }
.card-number { position: absolute; top: 7px; right: 20px; color: rgba(21,26,24,.08); font-family: Georgia, serif; font-size: 120px; font-weight: 700; line-height: 1; }
.current .card-number { color: rgba(255,255,255,.09); }
.curriculum-card > p { margin: 92px 0 8px; color: var(--muted); font-family: ui-monospace, monospace; font-size: 9px; font-weight: 900; letter-spacing: .12em; }
.current > p { color: #a9bbb4; }
.curriculum-card > p.card-summary { margin: 18px 0 0; max-width: 410px; color: #d4ded9; font-family: inherit; font-size: 14px; font-weight: 500; letter-spacing: 0; line-height: 1.9; }
.curriculum-card h3 { margin: 0; font-family: "Yu Mincho", Georgia, serif; font-size: clamp(24px, 3vw, 38px); line-height: 1.4; }
.card-tags { display: flex; margin-top: 28px; flex-wrap: wrap; gap: 7px; }
.card-tags span { padding: 4px 9px; border: 1px solid var(--line); font-family: ui-monospace, monospace; font-size: 9px; }
.current .card-tags span { border-color: rgba(255,255,255,.25); }
.curriculum-card > b { position: absolute; right: 30px; bottom: 26px; color: var(--acid); font-size: 11px; }

.goal-section { padding: 145px 5vw; color: white; background: var(--red); text-align: center; }
.goal-section .section-label { justify-content: center; color: #ffd8cf; }
.goal-section h2 { margin: 0 auto; font-family: "Yu Mincho", Georgia, serif; font-size: clamp(38px, 5.8vw, 78px); letter-spacing: -.06em; line-height: 1.3; }
.goal-section h2 em { color: var(--acid); }
.goal-section > p { margin: 36px 0 25px; font-weight: 800; }
.goal-parts { display: flex; max-width: 940px; margin: 0 auto 60px; padding: 19px; justify-content: center; flex-wrap: wrap; gap: 12px; border: 1px solid rgba(255,255,255,.35); }
.goal-parts span { padding: 5px 10px; color: var(--dark); background: white; font-size: 11px; font-weight: 900; }
.goal-parts i { color: var(--acid); font-style: normal; font-weight: 900; }
.goal-section blockquote { margin: 0 auto 44px; font-family: "Yu Mincho", Georgia, serif; font-size: clamp(22px, 3vw, 36px); font-weight: 700; line-height: 1.7; }
.light-button { border-color: white; color: var(--dark); background: white; }
.light-button:hover, .light-button:focus-visible { box-shadow: 7px 7px 0 var(--dark); }

.site-footer { display: flex; min-height: 130px; padding: 30px 5vw; align-items: center; justify-content: space-between; border-top: 1px solid var(--line); }
.site-footer p { color: var(--muted); font-size: 11px; }
.site-footer > a:last-child { font-family: ui-monospace, monospace; font-size: 10px; font-weight: 900; }

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

.hero-copy h1 { font-size: clamp(40px, 4.6vw, 68px); }

.contrast-list li { align-items: start; }
.contrast-list p { margin: -4px 0 0; font-weight: 600; }
.contrast-list b { display: block; margin-top: 3px; color: var(--red); }

.bottleneck-flow {
  display: flex;
  margin-top: 34px;
  padding: 20px;
  align-items: center;
  flex-wrap: wrap;
  gap: 9px;
  border: 1px solid rgba(255,255,255,.22);
  background: rgba(255,255,255,.04);
}

.bottleneck-flow span {
  padding: 6px 9px;
  color: var(--dark);
  background: white;
  font-size: 9px;
  font-weight: 900;
}

.bottleneck-flow i { color: #91a098; font-style: normal; }
.bottleneck-flow strong { padding: 6px 10px; color: white; background: var(--red); font-family: ui-monospace, monospace; font-size: 10px; }

.concept-definition .solution-line {
  display: flex;
  margin: 15px 0 0;
  align-items: center;
  gap: 13px;
  color: white;
  font-size: 13px;
}

.solution-line > span {
  flex: 0 0 auto;
  padding: 4px 8px;
  color: var(--dark);
  background: var(--acid);
  font-size: 9px;
  font-weight: 900;
}

.mother-bridge {
  margin-top: 72px;
  overflow: hidden;
  border: 1px solid var(--ink);
  background: var(--white);
}

.mother-bridge-intro {
  display: grid;
  padding: 42px;
  border-bottom: 1px solid var(--line);
  grid-template-columns: 0.7fr 1.25fr 1fr;
  gap: 35px;
  align-items: start;
}

.mother-bridge-intro > span {
  color: var(--red);
  font-family: ui-monospace, monospace;
  font-size: 9px;
  font-weight: 900;
  letter-spacing: 0.13em;
}

.mother-bridge-intro h3 {
  margin: 0;
  font-family: "Yu Mincho", "Hiragino Mincho ProN", Georgia, serif;
  font-size: clamp(25px, 3.1vw, 40px);
  line-height: 1.5;
}

.mother-bridge-intro h3 em { color: var(--red); }
.mother-bridge-intro p { margin: 0; color: var(--muted); font-size: 12px; line-height: 2; }

.mother-story-grid {
  display: grid;
  grid-template-columns: 0.82fr 1.18fr;
}

.mother-timeline {
  margin: 0;
  padding: 28px 34px;
  border-right: 1px solid var(--line);
  list-style: none;
}

.mother-timeline li {
  display: grid;
  padding: 15px 0;
  border-bottom: 1px solid var(--line);
  grid-template-columns: 38px 1fr;
  gap: 10px;
}

.mother-timeline li:last-child { border-bottom: 0; }
.mother-timeline span { color: var(--red); font-family: Georgia, serif; font-size: 15px; font-weight: 700; }
.mother-timeline p { margin: 0; font-size: 12px; font-weight: 700; }

.mother-complaint {
  padding: 34px;
  color: white;
  background: var(--dark);
}

.mother-complaint > span {
  color: var(--acid);
  font-family: ui-monospace, monospace;
  font-size: 9px;
  font-weight: 900;
  letter-spacing: 0.13em;
}

.mother-complaint > p {
  margin: 29px 0 24px;
  font-family: Georgia, serif;
  font-size: clamp(19px, 2.25vw, 30px);
  line-height: 1.65;
}

.mother-complaint > p b { color: #ff9a80; font-weight: 500; }
.mother-complaint > p i { color: #8fbfff; font-style: normal; }

.mother-complaint > small {
  display: block;
  color: #bac9c3;
  font-size: 10px;
  line-height: 1.9;
}

.mother-complaint > small strong { color: white; }

.mother-complaint > a {
  display: flex;
  margin-top: 26px;
  padding-top: 19px;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid rgba(255,255,255,.2);
  color: var(--acid);
  font-size: 11px;
  font-weight: 900;
  text-decoration: none;
}

.mother-complaint > a i { font-style: normal; }

.story-door {
  display: grid;
  min-height: 230px;
  padding: 36px;
  align-items: center;
  color: white;
  background: var(--dark);
  grid-template-columns: .85fr 1.15fr 52px;
  gap: 38px;
  text-decoration: none;
}

.story-door-route {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

.story-door-route span {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  border: 1px solid rgba(255,255,255,.35);
  border-radius: 50%;
  font-family: Georgia, serif;
  font-size: 13px;
}

.story-door-route span:last-child { border-color: var(--acid); color: var(--dark); background: var(--acid); }
.story-door-route i { color: #71837c; font-style: normal; }

.story-door small {
  color: var(--acid);
  font-family: ui-monospace, monospace;
  font-size: 9px;
  font-weight: 900;
  letter-spacing: .13em;
}

.story-door b {
  display: block;
  margin-top: 10px;
  font-family: "Yu Mincho", Georgia, serif;
  font-size: clamp(21px, 2.4vw, 31px);
  line-height: 1.5;
}

.story-door p { margin: 10px 0 0; color: #b6c5bf; font-size: 11px; }
.story-door > strong { display: grid; width: 46px; height: 46px; place-items: center; color: var(--dark); background: var(--acid); }
.story-door:hover > strong, .story-door:focus-visible > strong { transform: translateX(4px); }

.bridge-foot {
  display: grid;
  padding: 17px 28px;
  border-top: 1px solid var(--line);
  grid-template-columns: 120px 1fr;
  gap: 18px;
  background: var(--paper-2);
}

.bridge-foot span {
  color: var(--red);
  font-family: ui-monospace, monospace;
  font-size: 9px;
  font-weight: 900;
  letter-spacing: .12em;
}

.bridge-foot p { margin: 0; font-size: 11px; font-weight: 700; }

@media (max-width: 900px) {
  .site-header { grid-template-columns: 1fr auto; padding: 0 20px; }
  .desktop-nav, .header-cta { display: none; }
  .menu-button { display: grid; width: 42px; height: 42px; padding: 11px; place-items: center; border: 1px solid var(--ink); background: transparent; }
  .menu-button > span:not(.sr-only) { display: block; width: 18px; height: 1px; background: var(--ink); }
  .mobile-menu { position: absolute; top: 71px; right: 0; left: 0; padding: 16px 20px 24px; border-bottom: 1px solid var(--line); background: var(--paper); }
  .mobile-menu:not([hidden]) { display: grid; }
  .mobile-menu a { padding: 13px 0; border-bottom: 1px solid var(--line); font-size: 13px; font-weight: 800; text-decoration: none; }
  .hero { min-height: auto; padding: 74px 20px 105px; grid-template-columns: 1fr; gap: 72px; }
  .hero-lead br { display: none; }
  .hero-visual { max-width: 620px; }
  .concept-strip { justify-content: flex-start; }
  .problem-section, .phrase-section, .method-section, .curriculum-section { padding: 90px 20px; }
  .problem-grid, .concept-section, .learn-section { grid-template-columns: 1fr; }
  .problem-grid { gap: 45px; }
  .gap-statement { grid-template-columns: 1fr; gap: 10px; }
  .concept-section, .learn-section { padding: 95px 20px; gap: 55px; }
  .serious-note { grid-template-columns: 1fr; }
  .phrase-heading, .method-heading, .curriculum-heading { align-items: flex-start; flex-direction: column; }
  .phrase-grid { grid-template-columns: 1fr; }
  .phrase-grid article:nth-child(2) { transform: none; }
  .method-heading { display: grid; grid-template-columns: 1fr; }
  .method-heading .section-label { grid-column: 1; }
  .de-card { grid-template-columns: .6fr 1fr; }
  .de-mark { min-height: 210px; }
  .de-arrow { display: none; }
  .relation-split { grid-column: 1 / -1; grid-template-columns: 1fr 1fr; grid-template-rows: auto; border-top: 1px solid var(--line); }
  .relation-split article:first-child { border-right: 1px solid var(--line); border-bottom: 0; }
  .chunk-system { margin-top: 80px; padding-top: 55px; }
  .chunk-system-heading { grid-template-columns: 1fr; gap: 20px; }
  .learning-loop { grid-template-columns: 1fr; }
  .learning-loop li { min-height: auto; border-right: 0; border-bottom: 1px solid var(--ink); }
  .learning-loop li:last-child { border-bottom: 0; }
  .chunk-demo { grid-template-columns: 1fr; }
  .method-message { grid-template-columns: 1fr; gap: 22px; }
  .mother-bridge-intro { padding: 30px 24px; grid-template-columns: 1fr; gap: 18px; }
  .mother-story-grid { grid-template-columns: 1fr; }
  .story-door { grid-template-columns: 1fr 52px; gap: 25px; }
  .story-door-route { grid-column: 1 / -1; justify-content: flex-start; }
  .mother-timeline { border-right: 0; border-bottom: 1px solid var(--line); }
  .bridge-foot { grid-template-columns: 1fr; gap: 5px; }
  .learn-heading { position: static; }
  .lesson-grid { grid-template-columns: 1fr; }
  .curriculum-heading .section-label { position: static; margin: 0 0 24px; }
  .curriculum-heading { display: block; }
}

@media (max-width: 560px) {
  .hero h1 { font-size: 43px; }
  .hero-copy h1 { font-size: 38px; }
  .bottleneck-flow { align-items: stretch; flex-direction: column; }
  .bottleneck-flow i { transform: rotate(90deg); align-self: center; }
  .concept-definition .solution-line { align-items: flex-start; }
  .mother-timeline, .mother-complaint { padding: 24px 20px; }
  .story-door { padding: 28px 20px; }
  .story-door-route { gap: 4px; }
  .story-door-route span { width: 34px; height: 34px; }
  .hero-actions { align-items: stretch; flex-direction: column; }
  .primary-button { width: 100%; }
  .text-link { text-align: center; }
  .visual-note { right: -5px; }
  .problem-grid h2, .phrase-heading h2, .method-heading h2, .curriculum-heading h2, .learn-heading h2, .concept-intro h2 { font-size: 39px; }
  .known-list li { grid-template-columns: 85px 1fr; gap: 12px; }
  .gap-statement { padding: 28px 22px; }
  .concept-intro h2 { font-size: 53px; }
  .phrase-grid article { min-height: 260px; }
  .phrase-grid h3 { margin-top: 42px; }
  .de-card { grid-template-columns: 1fr; }
  .de-mark { min-height: 170px; }
  .de-copy { min-height: 215px; }
  .relation-split { grid-column: 1; grid-template-columns: 1fr; }
  .relation-split article:first-child { border-right: 0; border-bottom: 1px solid var(--line); }
  .integrated-sentence { display: grid; }
  .integrated-sentence > b { padding-top: 0; }
  .chunk-box { grid-template-columns: 1fr; }
  .lesson-banner { padding: 24px 20px; grid-template-columns: 1fr 42px; gap: 15px; }
  .lesson-no { grid-column: 1 / -1; }
  .lesson-title { font-size: 18px; }
  .learn-list li { grid-template-columns: 38px 1fr; }
  .curriculum-card { min-height: 350px; padding: 24px; }
  .goal-parts { align-items: center; flex-direction: column; }
  .goal-parts i { transform: rotate(90deg); }
  .site-footer { align-items: flex-start; flex-direction: column; gap: 20px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; }
}