:root {
  --ink: #122d35;
  --ink-soft: #456168;
  --cream: #f4f1e9;
  --paper: #fcfbf7;
  --line: #d7ded7;
  --orange: #e67c44;
  --orange-light: #f2a269;
  --sage: #a8bca2;
  --green: #698b72;
  --serif: Georgia, 'Times New Roman', serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; color: var(--ink); background: var(--cream); font-family: 'DM Sans', Arial, sans-serif; font-size: 16px; line-height: 1.55; }
a { color: inherit; text-decoration: none; }
button { color: inherit; font: inherit; }
.section-shell { width: min(1180px, calc(100% - 64px)); margin: 0 auto; }

.site-header { width: min(1280px, calc(100% - 64px)); height: 88px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; gap: 28px; border-bottom: 1px solid rgba(18, 45, 53, .15); }
.brand { display: flex; align-items: center; gap: 10px; font-family: Manrope, sans-serif; font-size: 16px; font-weight: 800; letter-spacing: -.06em; white-space: nowrap; }
.brand-light { color: var(--orange); font-weight: 500; margin-left: 4px; }
.brand-mark { width: 23px; height: 21px; display: flex; align-items: flex-end; gap: 3px; transform: rotate(-4deg); }
.brand-mark span { display: block; width: 5px; background: var(--orange); border-radius: 3px 3px 0 0; }
.brand-mark span:nth-child(1) { height: 10px; opacity: .6; }
.brand-mark span:nth-child(2) { height: 17px; }
.brand-mark span:nth-child(3) { height: 13px; opacity: .8; }
.main-nav { display: flex; align-items: center; gap: 34px; margin-left: auto; font-size: 13px; font-weight: 600; color: var(--ink-soft); }
.main-nav a, .header-link, .text-link, .source-row a, .back-top { transition: color .2s ease; }
.main-nav a:hover, .header-link:hover, .text-link:hover, .source-row a:hover, .back-top:hover { color: var(--orange); }
.header-link { color: var(--ink); font-size: 12px; font-family: 'DM Mono', monospace; letter-spacing: -.03em; }

.hero { min-height: 600px; display: grid; grid-template-columns: minmax(0, .94fr) minmax(420px, 1.06fr); align-items: center; gap: 70px; padding-top: 42px; padding-bottom: 58px; }
.eyebrow { margin: 0 0 20px; color: var(--orange); font-family: 'DM Mono', monospace; font-size: 11px; font-weight: 500; letter-spacing: .1em; text-transform: uppercase; }
.eyebrow-dot { display: inline-block; width: 7px; height: 7px; margin-right: 7px; border-radius: 50%; background: var(--orange); vertical-align: 1px; }
.hero h1 { max-width: 630px; margin: 0; font-family: Manrope, sans-serif; font-size: clamp(54px, 7vw, 92px); line-height: .96; letter-spacing: -.085em; font-weight: 800; }
h1 em, h2 span, .concept-panel h3 em { color: var(--orange); font-family: var(--serif); font-weight: 400; letter-spacing: -.06em; }
.hero-intro { max-width: 480px; margin: 31px 0 25px; color: var(--ink-soft); font-size: 17px; line-height: 1.65; }
.hero-actions { display: flex; align-items: center; gap: 25px; }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 24px; min-height: 49px; padding: 0 19px 0 22px; border-radius: 3px; font-size: 13px; font-weight: 700; transition: transform .2s ease, background .2s ease; }
.button:hover { transform: translateY(-2px); }
.button-dark { color: var(--cream); background: var(--ink); }
.button-dark:hover { background: var(--orange); }
.text-link { font-size: 13px; font-weight: 700; color: var(--ink-soft); }
.text-link span { margin-left: 7px; color: var(--orange); }
.hero-note { margin-top: 48px; color: #718187; font-size: 11px; }
.note-icon { display: inline-flex; justify-content: center; align-items: center; width: 18px; height: 18px; margin-right: 7px; border: 1px solid var(--sage); color: var(--green); border-radius: 50%; font-size: 9px; }

.hero-visual { position: relative; width: min(100%, 540px); aspect-ratio: 1 / .92; justify-self: end; background: var(--sage); overflow: hidden; border-radius: 2px; }
.hero-visual::before, .hero-visual::after { content: ''; position: absolute; border-radius: 50%; border: 1px solid rgba(18, 45, 53, .16); }
.hero-visual::before { width: 260px; height: 260px; top: -88px; right: -92px; }
.hero-visual::after { width: 170px; height: 170px; bottom: -63px; left: -58px; }
.orbit { position: absolute; inset: 13%; border: 1px solid rgba(18, 45, 53, .25); border-radius: 50%; }
.orbit-two { inset: 26% 18%; transform: rotate(49deg); border-color: rgba(252, 251, 247, .58); }
.visual-center { position: absolute; top: 50%; left: 50%; width: 184px; height: 184px; transform: translate(-50%, -50%); display: flex; align-items: center; flex-direction: column; justify-content: center; border-radius: 50%; background: var(--ink); color: var(--cream); text-align: center; box-shadow: 0 0 0 14px rgba(252, 251, 247, .09); }
.center-kicker { font-family: 'DM Mono', monospace; color: var(--orange-light); font-size: 9px; letter-spacing: .12em; }
.visual-center strong { margin-top: 9px; font-family: Manrope, sans-serif; font-size: 27px; line-height: 1; letter-spacing: -.07em; }
.visual-center strong i { color: var(--orange-light); font-family: var(--serif); font-weight: 400; }
.center-line { width: 31px; height: 1px; margin: 12px 0 7px; background: var(--orange); }
.center-caption { color: #a7bab5; font-family: 'DM Mono', monospace; font-size: 9px; line-height: 1.25; text-transform: uppercase; }
.visual-label { position: absolute; z-index: 1; color: var(--ink); font-family: 'DM Mono', monospace; font-size: 9px; letter-spacing: .08em; }
.label-top { top: 10%; left: 43%; } .label-right { top: 49%; right: 5%; transform: rotate(90deg); } .label-bottom { bottom: 10%; left: 39%; } .label-left { top: 47%; left: 3%; transform: rotate(-90deg); }
.spark { position: absolute; color: var(--orange); font-size: 27px; }
.spark-one { top: 16%; right: 24%; } .spark-two { bottom: 17%; right: 17%; color: var(--cream); font-size: 22px; } .spark-three { bottom: 24%; left: 20%; font-size: 18px; }

.principles { padding: 93px 0 113px; display: grid; grid-template-columns: .85fr 1.4fr; gap: 72px; border-top: 1px solid var(--line); }
.section-heading h2, .concepts h2, .path-intro h2, .glossary h2 { margin: 0; font-family: Manrope, sans-serif; font-size: clamp(35px, 4.2vw, 57px); line-height: 1.02; letter-spacing: -.075em; }
.section-heading > p:last-child { max-width: 325px; margin: 27px 0 0; color: var(--ink-soft); font-size: 15px; }
.principle-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.principle-card { position: relative; min-height: 224px; padding: 25px 24px; border: 1px solid var(--line); background: rgba(252, 251, 247, .46); }
.principle-card.card-highlight { color: var(--cream); background: var(--ink); border-color: var(--ink); }
.card-number { position: absolute; top: 22px; right: 23px; color: var(--orange); font-family: 'DM Mono', monospace; font-size: 10px; }
.card-icon { height: 49px; color: var(--orange); font-size: 31px; line-height: 1; }
.card-highlight .card-icon { color: var(--orange-light); }
.icon-eye { font-size: 25px; } .icon-loop { font-size: 36px; font-family: var(--serif); }
.principle-card h3 { margin: 17px 0 5px; font-family: Manrope, sans-serif; font-size: 20px; letter-spacing: -.04em; }
.principle-card p { margin: 0; color: var(--ink-soft); font-size: 13px; line-height: 1.55; }
.card-highlight p { color: #b2c4c0; }

.concepts { padding: 105px 0 110px; border-top: 1px solid var(--line); }
.concepts-head { display: flex; justify-content: space-between; align-items: flex-end; gap: 30px; margin-bottom: 51px; }
.section-aside { max-width: 260px; margin: 0 3% 4px 0; color: var(--ink-soft); font-size: 13px; }
.concept-layout { display: grid; grid-template-columns: .7fr 1.3fr; min-height: 421px; }
.concept-tabs { display: flex; flex-direction: column; border-top: 1px solid var(--line); }
.concept-tab { display: flex; align-items: center; gap: 14px; min-height: 77px; padding: 0 19px 0 0; border: 0; border-bottom: 1px solid var(--line); background: transparent; cursor: pointer; color: var(--ink-soft); text-align: left; font-family: Manrope, sans-serif; font-size: 19px; font-weight: 700; letter-spacing: -.05em; transition: color .2s ease, padding .2s ease; }
.concept-tab span { color: var(--orange); font-family: 'DM Mono', monospace; font-size: 10px; letter-spacing: 0; }
.concept-tab b { margin-left: auto; color: transparent; font-size: 20px; font-weight: 400; }
.concept-tab:hover, .concept-tab.active { color: var(--ink); padding-left: 13px; }
.concept-tab.active { border-bottom-color: var(--orange); }
.concept-tab.active b { color: var(--orange); }
.concept-panel-wrap { background: var(--paper); }
.concept-panel { min-height: 421px; padding: 35px 47px 30px; }
.panel-top, .panel-footer { display: flex; justify-content: space-between; align-items: center; }
.panel-tag, .panel-number, .panel-footer { color: var(--green); font-family: 'DM Mono', monospace; font-size: 10px; letter-spacing: .06em; }
.panel-number { color: #a2b0ab; }
.concept-panel h3 { margin: 48px 0 20px; font-family: Manrope, sans-serif; font-size: clamp(26px, 3vw, 40px); line-height: 1.1; letter-spacing: -.07em; }
.concept-panel > p { max-width: 520px; margin: 0; color: var(--ink-soft); font-size: 14px; line-height: 1.7; }
.question-box { display: flex; align-items: center; gap: 19px; margin: 30px 0 29px; padding: 15px 17px; border-left: 3px solid var(--orange); background: #f1ebe0; }
.question-box span { color: var(--orange); font-family: 'DM Mono', monospace; font-size: 9px; text-transform: uppercase; }
.question-box strong { font-family: var(--serif); font-size: 15px; font-weight: 400; }
.mini-bar { display: block; width: 76px; height: 3px; background: #d8e1d8; }
.mini-bar i { display: block; height: 100%; background: var(--orange); }

.learning-path { padding: 111px 0 116px; display: grid; grid-template-columns: .78fr 1.22fr; gap: 110px; border-top: 1px solid var(--line); }
.path-intro > p:last-child { max-width: 280px; margin: 25px 0 0; color: var(--ink-soft); font-size: 14px; }
.path-list { border-top: 1px solid var(--ink); }
.path-item { display: grid; grid-template-columns: 46px 1fr 22px; align-items: center; gap: 18px; min-height: 93px; border-bottom: 1px solid var(--line); }
.path-index { align-self: start; padding-top: 28px; color: var(--orange); font-family: 'DM Mono', monospace; font-size: 10px; }
.path-item h3 { margin: 0 0 3px; font-family: Manrope, sans-serif; font-size: 16px; letter-spacing: -.035em; }
.path-item p { margin: 0; color: var(--ink-soft); font-size: 12px; }
.path-arrow { color: var(--orange); font-size: 19px; }

.glossary { padding: 107px 0 109px; border-top: 1px solid var(--line); display: grid; grid-template-columns: .72fr 1.28fr; gap: 110px; }
.glossary-head { display: flex; justify-content: space-between; align-items: flex-start; }
.glossary-mark { color: var(--orange); font-family: var(--serif); font-size: 48px; font-style: italic; line-height: .8; }
.accordion-list { border-top: 1px solid var(--ink); }
details { border-bottom: 1px solid var(--line); }
summary { display: flex; align-items: center; justify-content: space-between; min-height: 66px; cursor: pointer; list-style: none; font-family: Manrope, sans-serif; font-size: 18px; font-weight: 700; letter-spacing: -.04em; }
summary::-webkit-details-marker { display: none; }
summary i { color: var(--orange); font-size: 24px; font-style: normal; font-weight: 400; transition: transform .2s ease; }
details[open] summary i { transform: rotate(45deg); }
details p { max-width: 590px; margin: -4px 35px 21px 0; color: var(--ink-soft); font-size: 13px; line-height: 1.65; }

.trust { padding: 0 0 72px; }
.trust-card { display: grid; grid-template-columns: 60px 1fr 1.1fr; align-items: start; gap: 28px; padding: 42px 49px; background: var(--ink); color: var(--cream); }
.trust-symbol { color: var(--orange-light); font-size: 39px; line-height: 1; }
.trust-card .eyebrow { color: var(--orange-light); }
.trust-card h2 { margin: 0; font-family: Manrope, sans-serif; font-size: clamp(25px, 3vw, 36px); line-height: 1.05; letter-spacing: -.07em; }
.trust-card h2 span { color: var(--orange-light); }
.trust-copy { max-width: 430px; color: #b5c5c2; font-size: 12px; line-height: 1.65; }
.trust-copy p { margin: 0 0 16px; }
.trust-copy p:last-child { margin-bottom: 0; }
.source-row { display: flex; justify-content: space-between; gap: 25px; padding: 19px 0 0; color: #74858a; font-family: 'DM Mono', monospace; font-size: 9px; letter-spacing: .04em; text-transform: uppercase; }
.source-row a { color: var(--ink-soft); }

.site-footer { display: flex; align-items: center; justify-content: space-between; min-height: 90px; border-top: 1px solid var(--line); color: #76878a; font-size: 11px; }
.site-footer .brand { color: var(--ink); font-size: 14px; }
.back-top { color: var(--ink); font-family: 'DM Mono', monospace; font-size: 10px; }

@media (max-width: 900px) {
  .main-nav { gap: 17px; }
  .header-link { display: none; }
  .hero { grid-template-columns: 1fr; gap: 45px; padding-top: 70px; }
  .hero-visual { justify-self: stretch; width: 100%; }
  .principles, .learning-path, .glossary { grid-template-columns: 1fr; gap: 47px; }
  .principles { padding-top: 78px; }
  .learning-path, .glossary { padding-top: 80px; }
  .concept-layout { grid-template-columns: 1fr; }
  .concept-tabs { flex-direction: row; border-top: 0; gap: 3px; }
  .concept-tab { min-height: 61px; padding: 0 15px 0 0; font-size: 16px; }
  .concept-tab.active, .concept-tab:hover { padding-left: 0; }
  .concept-panel { min-height: 380px; }
  .trust-card { grid-template-columns: 48px 1fr; }
  .trust-copy { grid-column: 2; }
}

@media (max-width: 620px) {
  .section-shell, .site-header { width: min(100% - 36px, 1180px); }
  .site-header { height: 72px; }
  .main-nav { display: none; }
  .hero { min-height: auto; padding: 63px 0 72px; }
  .hero h1 { font-size: 62px; }
  .hero-intro { margin-top: 24px; font-size: 15px; }
  .hero-actions { gap: 17px; }
  .hero-note { margin-top: 35px; }
  .hero-visual { aspect-ratio: 1 / 1.02; }
  .visual-center { width: 160px; height: 160px; }
  .visual-center strong { font-size: 23px; }
  .principle-grid { grid-template-columns: 1fr; }
  .principle-card { min-height: 190px; }
  .concepts-head { display: block; margin-bottom: 33px; }
  .section-aside { margin-top: 22px; }
  .concept-tabs { overflow-x: auto; }
  .concept-tab { flex: 1 0 125px; }
  .concept-panel { padding: 27px 23px; min-height: 440px; }
  .concept-panel h3 { margin-top: 45px; font-size: 29px; }
  .question-box { display: block; }
  .question-box strong { display: block; margin-top: 7px; }
  .learning-path { gap: 35px; }
  .path-item { grid-template-columns: 32px 1fr 15px; gap: 10px; }
  .path-item h3 { font-size: 14px; }
  .path-item p { font-size: 11px; }
  .glossary { gap: 38px; }
  .trust-card { grid-template-columns: 1fr; gap: 20px; padding: 32px 25px; }
  .trust-copy { grid-column: auto; }
  .source-row { display: block; line-height: 2; }
  .source-row a { display: block; }
  .site-footer { gap: 18px; flex-wrap: wrap; padding: 20px 0; }
  .site-footer > span { order: 3; width: 100%; }
}