:root {
  --mint: #d8f2e9;
  --mint-deep: #087a70;
  --teal: #063f3b;
  --coral: #f06c4f;
  --yellow: #f1cf54;
  --white: #f8fbf7;
  --ink: #102c2b;
  --muted: #5d706d;
  --line: #b4ccc4;
  --sans: "Avenir Next", "Noto Sans SC", "PingFang SC", sans-serif;
  --mono: "SFMono-Regular", Consolas, monospace;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--mint); color: var(--ink); font-family: var(--sans); font-size: 17px; line-height: 1.72; }
a { color: inherit; text-underline-offset: .22em; }
img { display: block; width: 100%; height: auto; }
button { font: inherit; }
:focus-visible { outline: 3px solid var(--coral); outline-offset: 4px; }
.skip { position: fixed; top: -70px; left: 12px; z-index: 20; padding: 8px 12px; background: var(--teal); color: white; }
.skip:focus { top: 12px; }
.head { background: var(--teal); color: var(--white); }
.head-inner { display: flex; width: min(calc(100% - 48px), 1320px); min-height: 100px; align-items: center; justify-content: space-between; gap: 28px; margin: auto; }
.brand { display: flex; align-items: center; gap: 13px; text-decoration: none; }
.brand > span:last-child { display: grid; grid-template-columns: auto auto; gap: 0 4px; align-items: baseline; }
.brand b { font-family: var(--mono); font-size: 25px; letter-spacing: -.07em; line-height: 1; }
.brand b:nth-child(2) { color: var(--yellow); }
.brand small { grid-column: 1 / -1; color: #8db8b0; font: 9px var(--mono); letter-spacing: .14em; }
.switch { position: relative; width: 42px; height: 24px; border: 2px solid var(--yellow); border-radius: 15px; background: var(--mint-deep); }
.switch::after { position: absolute; top: 3px; right: 3px; width: 14px; height: 14px; border-radius: 50%; background: var(--yellow); content: ""; }
.learning-mode { display: flex; align-items: center; gap: 8px; margin: 0; color: #a7c4be; font: 10px var(--mono); letter-spacing: .1em; }
.learning-mode i { width: 8px; height: 8px; border-radius: 50%; background: var(--coral); }
.head nav { display: flex; width: min(calc(100% - 48px), 1320px); margin: auto; border-top: 1px solid #275a54; }
.head nav a { padding: 12px 24px; border-right: 1px solid #275a54; color: #c9dfda; font-size: 12px; font-weight: 700; text-decoration: none; }
.head nav a:first-child { padding-left: 0; }
.head nav a:hover, .head nav a[aria-current="page"] { color: var(--yellow); }
.menu { display: none; }
.hero { display: grid; width: min(calc(100% - 48px), 1320px); grid-template-columns: 1.07fr 1fr; gap: 42px; align-items: center; margin: 48px auto 66px; }
.hero-board { padding: 28px; border: 2px solid var(--teal); background: var(--yellow); }
.label { margin: 0 0 9px; color: var(--mint-deep); font: 800 10px var(--mono); letter-spacing: .13em; text-transform: uppercase; }
.hero-board .label { color: var(--teal); }
.hero h1 { margin: 0 0 20px; font-size: clamp(55px, 8vw, 106px); font-weight: 860; letter-spacing: -.085em; line-height: .86; }
.hero h1 em { color: var(--mint-deep); font-style: normal; }
.hero-board > p:not(.label) { max-width: 560px; margin: 0; font-size: 18px; }
.path-tags { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 23px; }
.path-tags span { padding: 5px 8px; border: 1px solid var(--teal); background: var(--white); font: 9px var(--mono); }
.hero-lesson .lesson { border: 2px solid var(--teal); padding: 16px; background: var(--white); }
.hero-lesson .lesson-img img { aspect-ratio: 16 / 10; object-fit: cover; }
.hero-lesson h2 { font-size: 31px; }
.lesson { min-width: 0; padding: 0 0 23px; border-bottom: 2px solid var(--teal); }
.step { display: flex; justify-content: space-between; margin: 0 0 11px; color: var(--mint-deep); font: 800 9px var(--mono); letter-spacing: .11em; }
.step span { color: var(--muted); font-weight: 400; }
.lesson-img { display: block; overflow: hidden; margin-bottom: 13px; border: 2px solid var(--teal); }
.lesson-img img { aspect-ratio: 4 / 3; object-fit: cover; transition: transform .35s ease; }
.lesson-img:hover img { transform: scale(1.035); }
.topic { margin: 0 0 6px; color: var(--coral); font-size: 10px; font-weight: 800; letter-spacing: .1em; }
.lesson h2 { margin: 0 0 7px; font-size: 23px; font-weight: 780; letter-spacing: -.035em; line-height: 1.2; }
.lesson h2 a { text-decoration: none; }
.lesson h2 a:hover { color: var(--mint-deep); }
.lesson > p:last-child { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.55; }
.hero-lesson h2 { font-size: 30px; }
.main-layout { display: grid; width: min(calc(100% - 48px), 1320px); grid-template-columns: 240px minmax(0,1fr); gap: 42px; align-items: start; margin: 0 auto 80px; }
.path { position: sticky; top: 15px; }
.path-note { color: var(--muted); font-size: 12px; }
.path nav { border-top: 2px solid var(--teal); }
.path nav a { display: flex; justify-content: space-between; padding: 11px 0; border-bottom: 1px solid var(--line); text-decoration: none; }
.path nav a span { font-size: 13px; font-weight: 800; }
.path nav a b { color: var(--mint-deep); font: 10px var(--mono); }
.path nav a:hover span { color: var(--coral); }
.check-box { margin-top: 20px; padding: 16px; border: 2px solid var(--teal); background: var(--white); font-size: 12px; }
.check-box p { margin: 7px 0 0; color: var(--muted); }
.list-title { display: flex; justify-content: space-between; gap: 18px; align-items: end; padding: 13px 0; border-top: 2px solid var(--teal); border-bottom: 2px solid var(--teal); }
.list-title h2 { margin: 0; font-size: 34px; letter-spacing: -.05em; }
.list-title span { color: var(--muted); font: 9px var(--mono); }
.lessons { display: grid; grid-template-columns: 1fr 1fr; gap: 32px 22px; padding-top: 22px; }
.lesson.featured { grid-column: 1 / -1; display: grid; grid-template-columns: .9fr 1.1fr; column-gap: 20px; }
.lesson.featured .step, .lesson.featured .topic, .lesson.featured h2, .lesson.featured > p:last-child { grid-column: 2; }
.lesson.featured .lesson-img { grid-row: 1 / 5; margin: 0; }
.lesson.featured h2 { font-size: 28px; }
.archive { width: min(calc(100% - 48px), 1240px); margin: 48px auto 80px; }
.archive > header { max-width: 870px; padding: 22px 0 36px; border-top: 2px solid var(--teal); }
.archive > header h1 { margin: 0 0 10px; font-size: clamp(60px, 10vw, 126px); letter-spacing: -.08em; line-height: .86; }
.archive > header > p:last-child { max-width: 680px; color: var(--muted); font-size: 18px; }
.archive .main-layout { width: 100%; margin: 0; }
.article { width: min(calc(100% - 48px), 1200px); margin: 48px auto 80px; }
.article header { max-width: 920px; margin: 0 auto 38px; text-align: center; }
.article header h1 { margin: 12px 0 22px; font-size: clamp(46px, 7.3vw, 92px); letter-spacing: -.07em; line-height: .98; }
.outcome { display: grid; max-width: 760px; grid-template-columns: 100px 1fr; gap: 14px; margin: 0 auto; padding: 16px; border: 2px solid var(--teal); background: var(--yellow); text-align: left; }
.outcome b { font-size: 12px; }
.outcome p { margin: 0; font-size: 14px; }
.meta { margin-top: 14px; color: var(--muted); font: 10px var(--mono); }
.lesson-layout { display: grid; grid-template-columns: 180px minmax(0, 720px) 190px; gap: 32px; align-items: start; justify-content: center; }
.toc, .lesson-side { position: sticky; top: 15px; }
.toc > a { display: block; padding: 8px 0; border-bottom: 1px solid var(--line); color: var(--muted); font-size: 12px; text-decoration: none; }
.toc > a:hover, .toc > a.active { color: var(--mint-deep); font-weight: 800; }
.progress { display: flex; flex-wrap: wrap; gap: 4px; margin-top: 18px; padding: 12px; border: 2px solid var(--teal); background: var(--white); font: 8px var(--mono); }
.progress b { width: 100%; color: var(--coral); }
.progress span { padding: 2px 4px; background: var(--mint); }
.lesson-side > div { margin-bottom: 18px; padding: 16px; border: 2px solid var(--teal); background: var(--white); font-size: 13px; }
.lesson-side p:not(.label) { color: var(--muted); font-size: 12px; line-height: 1.6; }
.lesson-side a { color: var(--mint-deep); font-weight: 800; }
.prose { min-width: 0; }
.prose figure { margin: 0 0 28px; }
.prose figure img { aspect-ratio: 3 / 2; object-fit: cover; border: 2px solid var(--teal); }
.prose figcaption { margin-top: 6px; color: var(--muted); font: 9px var(--mono); }
.intro p:first-child { color: var(--mint-deep); font-size: 20px; font-weight: 650; }
.prose section { scroll-margin-top: 20px; }
.prose h2 { margin: 34px 0 14px; padding-top: 12px; border-top: 2px solid var(--teal); font-size: 30px; letter-spacing: -.045em; line-height: 1.2; }
.prose p { margin: 0 0 18px; font-size: 17px; line-height: 1.9; }
.prose ol, .prose ul { padding: 19px 24px 19px 42px; border: 1px solid var(--line); background: var(--white); }
.prose li { margin-bottom: 9px; }
.practice-card { margin-top: 30px; padding: 20px; border-left: 7px solid var(--coral); background: var(--white); }
.practice-card p:last-child { margin: 0; font-size: 14px; }
.more { margin-top: 55px; padding-top: 18px; border-top: 2px solid var(--teal); }
.more > div { display: grid; grid-template-columns: repeat(3,1fr); gap: 16px; margin-top: 16px; }
.more a { padding: 15px; border: 2px solid var(--teal); background: var(--white); text-decoration: none; }
.more small { display: block; color: var(--coral); font: 9px var(--mono); }
.more b { display: block; margin-top: 5px; font-size: 16px; line-height: 1.35; }
.about { width: min(calc(100% - 48px), 1120px); margin: 56px auto 80px; }
.about h1 { margin: 12px 0 24px; font-size: clamp(60px, 10vw, 126px); letter-spacing: -.085em; line-height: .87; }
.about h1 em { color: var(--mint-deep); font-style: normal; }
.lead { max-width: 760px; color: var(--muted); font-size: 20px; }
.about-grid { display: grid; grid-template-columns: 1fr 1fr; margin-top: 48px; border-top: 2px solid var(--teal); }
.about-grid section { padding: 28px 38px 28px 0; border-bottom: 1px solid var(--line); }
.about-grid section:nth-child(even) { padding-left: 38px; border-left: 1px solid var(--line); }
.about-grid h2 { margin: 8px 0 12px; font-size: 29px; letter-spacing: -.04em; }
.about-grid p:not(.label) { color: var(--muted); font-size: 15px; }
.about-grid a { color: var(--mint-deep); font-weight: 800; }
.foot { padding: 45px 0 30px; background: var(--teal); color: var(--white); }
.foot-inner { display: grid; width: min(calc(100% - 48px), 1320px); grid-template-columns: 1.4fr .75fr .8fr 1fr; gap: 36px; margin: auto; }
.foot .label { color: var(--yellow); }
.foot h2 { margin: 0 0 10px; font-size: 28px; letter-spacing: -.045em; line-height: 1.15; }
.foot p:not(.label), .foot-inner section > a { color: #b5d6cf; font-size: 12px; }
.foot-inner section > a { display: block; margin: 5px 0; }
@media (max-width: 980px) {
  .hero { grid-template-columns: 1fr; }
  .lesson-layout { grid-template-columns: 155px minmax(0,1fr); }
  .lesson-side { display: none; }
}
@media (max-width: 720px) {
  .head-inner, .head nav, .hero, .main-layout, .archive, .article, .about, .foot-inner { width: min(calc(100% - 28px), 1320px); }
  .head-inner { min-height: 82px; }
  .learning-mode { display: none; }
  .menu { display: block; padding: 8px 12px; border: 1px solid var(--yellow); background: transparent; color: var(--yellow); font-size: 11px; }
  .head nav { display: none; padding: 7px; }
  .head nav.open { display: grid; }
  .head nav a { padding: 10px 3px; border-right: 0; border-bottom: 1px solid #275a54; }
  .hero { display: block; margin-top: 26px; }
  .hero-board { padding: 20px; }
  .hero h1 { font-size: 57px; }
  .hero-board > p:not(.label) { font-size: 16px; }
  .hero-lesson { margin-top: 25px; }
  .main-layout { display: block; }
  .path { position: static; margin-bottom: 28px; }
  .path-note, .check-box { display: none; }
  .path nav { display: flex; overflow-x: auto; }
  .path nav a { min-width: max-content; gap: 11px; padding: 9px 10px; border: 1px solid var(--line); border-top: 0; }
  .list-title { align-items: start; }
  .list-title h2 { font-size: 28px; }
  .lessons { display: block; }
  .lesson { margin-bottom: 28px; }
  .lesson.featured { display: block; }
  .lesson.featured h2, .lesson h2 { font-size: 23px; }
  .archive { margin-top: 30px; }
  .archive > header h1 { font-size: 68px; }
  .article { margin-top: 28px; }
  .article header h1 { font-size: 41px; }
  .outcome { grid-template-columns: 1fr; gap: 6px; }
  .lesson-layout { display: block; }
  .toc, .lesson-side { display: none; }
  .prose h2 { font-size: 27px; }
  .prose p { font-size: 16px; line-height: 1.88; }
  .more > div { grid-template-columns: 1fr; }
  .more a:nth-child(n+3) { display: none; }
  .about { margin-top: 32px; }
  .about h1 { font-size: 54px; }
  .lead { font-size: 17px; }
  .about-grid { display: block; }
  .about-grid section, .about-grid section:nth-child(even) { padding: 24px 0; border-left: 0; }
  .foot-inner { grid-template-columns: 1fr; gap: 18px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}