/* study_chemistry.hk — one canvas, product-led composition. */
:root{
  --paper:#F6F5F0;--raised:#fff;--grey:#EAECE6;--ink:#1D241F;--muted:#646C65;
  --brand:#245846;--brand-hover:#164533;--mint:#DDE9DF;--mint-300:#C4DDCB;
  --line:#DADFD6;--deep:#142A21;--deep-raised:#1D392C;--deep-line:#355144;
  --on-deep:#F4F6F1;--on-deep-muted:#C4D3C6;--coral:#A53E43;
  --sans:-apple-system,BlinkMacSystemFont,"Helvetica Neue","PingFang HK","Noto Sans TC",Arial,sans-serif;
  --serif:var(--sans);--mono:ui-monospace,"SF Mono",monospace;
  --wrap:1120px;--gutter:clamp(24px,5vw,64px);--ease:cubic-bezier(.23,1,.32,1);
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:86px;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font:17px/1.7 var(--sans);-webkit-font-smoothing:antialiased}
h1,h2,h3,p,figure,dl,dd,ul,ol{margin:0;padding:0}
ul,ol{list-style:none}
a{color:inherit;text-decoration:none}
button{font:inherit;cursor:pointer;color:inherit}
img,svg{display:block;max-width:100%}
h1,h2,h3{text-wrap:balance;letter-spacing:-.025em;line-height:1.2;font-weight:650}
p,li{text-wrap:pretty}
strong,b{font-weight:600}
:focus-visible{outline:2px solid var(--brand);outline-offset:5px}
::selection{background:var(--mint)}
.wrap{width:min(var(--wrap),calc(100% - 2 * var(--gutter)));margin-inline:auto}
.skip{position:fixed;top:-100px;left:16px;padding:12px 20px;background:var(--brand);color:#fff;z-index:100}
.skip:focus{top:12px}
.progress,.arr,.dock{display:none}
/* Functional chrome stays visually separate from the story. */
.header{position:sticky;top:0;z-index:50;background:rgba(246,245,240,.9);backdrop-filter:blur(20px);-webkit-backdrop-filter:blur(20px)}
.header::after{content:"";position:absolute;inset:auto 0 0;height:1px;background:var(--line);opacity:0;transition:opacity var(--motion-color)}
.header.scrolled::after{opacity:1}
.header-in{width:min(1200px,calc(100% - 48px));margin:auto;min-height:64px;display:flex;align-items:center;gap:36px}
.brand{display:flex;align-items:center;gap:10px;font-size:14px;font-weight:600;white-space:nowrap;letter-spacing:-.015em}
.brand img{width:28px;height:28px;border-radius:7px}
.nav{display:flex;align-items:center;gap:28px;margin-left:auto;font-size:13px;color:var(--muted)}
.nav a{display:flex;align-items:center;min-height:44px;position:relative;white-space:nowrap}
.nav a[aria-current]{color:var(--ink)}
.nav a[aria-current]::after{content:"";position:absolute;bottom:5px;left:0;right:0;height:2px;background:var(--brand)}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:46px;padding:11px 24px;background:var(--brand);color:#fff;border:1px solid var(--brand);border-radius:999px;font-size:15px;font-weight:500;line-height:1.35;text-align:center;white-space:normal;touch-action:manipulation}
.btn-sm{min-height:34px;padding:7px 17px;font-size:12px;white-space:nowrap;flex-shrink:0}
.btn-ghost{background:transparent;color:var(--brand);border-color:transparent}
.btn-line,.btn-light{background:transparent;color:var(--brand);border-color:var(--line)}
.actions{display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:12px}
.link{display:inline-flex;align-items:center;gap:8px;min-height:44px;font-size:14px;font-weight:500;color:var(--brand)}
.link span{font-size:18px}
.fine{font-size:12px;line-height:1.7;color:var(--muted)}
.kicker{font-size:14px;font-weight:600;line-height:1.5;color:var(--brand);margin-bottom:12px}
/* Hero: editorial type, then an expansive, balanced spread of real notes. */
.hero{padding:72px 0 0;overflow:hidden;text-align:center}
.hero-in{display:flex;flex-direction:column;align-items:center}
.hero .kicker{font-size:15px;margin-bottom:20px}
.hero h1{font-size:clamp(40px,5.4vw,74px);line-height:1.15;letter-spacing:-.04em;max-width:15em}
.hero .lede{max-width:30em;font-size:20px;line-height:1.7;color:var(--muted);margin-top:24px}
.hero .actions{margin-top:28px}
.hero-note{font-size:12px;color:var(--muted);margin-top:22px;max-width:42em}
.hero-material{position:relative;display:block;width:min(1040px,95%);aspect-ratio:2.2;margin:64px auto 0;isolation:isolate}
.hero-sheet{position:absolute;width:34%;height:auto;border:1px solid #E4E7DF;border-radius:3px;box-shadow:0 20px 42px -26px rgba(27,47,33,.3)}
.hero-sheet-left{left:4%;top:12%;transform:rotate(-8deg)}
.hero-sheet-back{right:4%;top:12%;transform:rotate(8deg)}
.hero-sheet-front{width:36%;left:32%;top:0;z-index:2}
.hero-material::after{content:"";position:absolute;inset:65% -5% -2%;z-index:3;background:linear-gradient(transparent,var(--paper) 94%);pointer-events:none}
/* Chapter heads are an introduction to a composition, not a stack of paragraphs. */
.section{padding:132px 0}
.head{max-width:800px;margin:0 auto 52px;text-align:center}
.head h2{font-size:clamp(36px,4.2vw,56px);letter-spacing:-.035em}
.head .section-subtitle{font-size:24px;line-height:1.4;font-weight:600;color:var(--ink);margin-top:20px}
.section-subtitle em{font-style:normal;color:var(--brand)}
.head>p:not(.section-subtitle){font-size:18px;line-height:1.7;color:var(--muted);max-width:34em;margin:20px auto 0}
/* Open, typographic statements, not a row of rectangles. */
.fit{padding:72px 0 96px}
.fit .head{margin-bottom:48px}
.fit .section-subtitle{font-size:17px;font-weight:400;color:var(--muted);margin-top:14px}
.fit-list{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:60px;text-align:center}
.fit-n{display:block;width:30px;height:30px;margin:0 auto 20px;border:1px solid var(--line);border-radius:50%;font-size:12px;line-height:28px;color:var(--muted)}
.fit-list p{font-size:15px;line-height:1.8;color:var(--muted)}
.fit-list strong{display:block;color:var(--ink);font-size:23px;line-height:1.45;letter-spacing:-.025em;margin-top:9px}
/* A clear viewing stage. Details sit underneath, where they belong. */
.sample{padding-top:100px}
.sample-in{max-width:1040px}
.sample .head{margin-bottom:44px}
.sample .head .section-subtitle{font-size:28px;margin-top:18px}
.sample .head .section-subtitle br{display:none}
.sample .head>p:not(.section-subtitle){max-width:33em}
.player{position:relative;width:100%;aspect-ratio:16/9;background:var(--deep);border-radius:18px;overflow:hidden;box-shadow:0 24px 52px -38px rgba(23,44,29,.4)}
.player-btn{all:unset;cursor:pointer;display:block;position:absolute;inset:0;width:100%;height:100%}
.player-btn img{width:100%;height:100%;object-fit:cover}
.play{position:absolute;right:24px;bottom:24px;width:62px;height:62px;border-radius:50%;display:grid;place-items:center;background:var(--brand);color:#fff;box-shadow:0 8px 24px #0002}
.play svg{width:23px;height:23px;fill:currentColor;margin-left:3px}
.player-label{position:absolute;left:24px;bottom:24px;display:flex;gap:12px;align-items:baseline;color:#fff;padding:8px 14px;background:rgba(20,42,33,.82);border-radius:7px;font-size:15px}
.player-label small{font-size:12px;color:var(--mint-300)}
.player iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.sample-caption{max-width:1040px;display:grid;grid-template-columns:auto 1fr;align-items:start;gap:32px;margin-top:20px}
.sample-links{display:flex;gap:24px;flex-wrap:wrap}
.sample-caption-copy{max-width:36em;justify-self:end}
.sample-caption-copy .fine{font-size:11px;margin-top:6px}
.sample-caption-copy .fine:first-child{color:var(--ink)}
.notes{max-width:960px;margin-top:88px}
.notes-head{display:flex;justify-content:space-between;align-items:end;gap:24px;margin-bottom:30px}
.notes-head h3{font-size:22px;line-height:1.4;letter-spacing:-.02em}
.notes-head .kicker{font-size:12px;margin-bottom:8px}
.notes-meta{font-size:12px;color:var(--muted);white-space:nowrap}
.notes-rail{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:22px}
.notes-rail button{all:unset;display:block;position:relative;cursor:zoom-in;background:#fff;border-radius:3px;box-shadow:0 4px 20px -12px #142A2144;outline:1px solid #142A2110}
.notes-rail img{width:100%;height:auto;aspect-ratio:1200/1697}
.notes-rail span{position:absolute;bottom:8px;right:8px;width:23px;height:23px;border-radius:50%;background:var(--paper);color:var(--muted);font-size:11px;text-align:center;line-height:23px}
/* Course comparison uses a consistent product silhouette, on the same canvas. */
#courses{padding-top:96px}
#courses .head .section-subtitle{font-size:28px}
.courses{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:56px;margin-top:72px}
.course{display:flex;flex-direction:column;align-items:flex-start;min-width:0}
.cover{position:relative;width:132px;height:176px;align-self:center;margin-bottom:38px;background:var(--brand);color:#fff;border-radius:2px 7px 7px 2px;padding:18px 15px 18px 21px;display:flex;flex-direction:column;justify-content:space-between;box-shadow:4px 12px 18px -13px #142A2155,inset 5px 0 0 #0001,inset 6px 0 0 #ffffff1a;transform:rotate(-4deg)}
.course:nth-child(2) .cover{transform:rotate(0);background:#385349}
.course:nth-child(3) .cover{transform:rotate(4deg);background:#60745F}
.cover small{font-size:10px;letter-spacing:.12em;font-weight:600;color:var(--mint-300)}
.cover span{font-size:21px;letter-spacing:-.04em;line-height:1.1;font-weight:500}
.course h3{font-size:23px;line-height:1.25;letter-spacing:-.025em}
.course .zh{font-size:13px;margin-top:7px;color:var(--muted)}
.tag{display:inline-block;font-size:11px;font-weight:500;color:var(--brand);line-height:1.4;margin-top:10px}
.course .blurb{font-size:15px;color:var(--muted);line-height:1.7;margin-top:20px;min-height:76px}
.price{font-size:28px;font-weight:600;letter-spacing:-.025em;line-height:1.2;font-variant-numeric:tabular-nums;white-space:nowrap}
.course .price{margin-top:auto;padding-top:20px}
.course .go{display:inline-flex;align-items:center;gap:6px;min-height:44px;margin-top:12px;color:var(--brand);font-size:14px;font-weight:500}
.bundles{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:64px;margin-top:64px;padding-top:36px;border-top:1px solid var(--line)}
.bundle{display:grid;grid-template-columns:1fr auto;column-gap:24px;align-items:start}
.bundle-tag{font-size:20px;font-weight:600;line-height:1.5}
.bundle .tag{margin:0 0 0 8px;padding:2px 7px;background:var(--mint);border-radius:5px;font-size:10px;vertical-align:middle}
.bundle h3{grid-column:1;font-size:12px;line-height:1.5;font-weight:400;color:var(--muted);margin-top:6px}
.bundle-save{grid-column:1;font-size:12px;color:var(--muted);margin-top:6px}
.bundle .price{grid-column:2;grid-row:1 / span 3;align-self:center;font-size:30px}
.bundle .btn{grid-column:1 / -1;justify-self:start;margin-top:20px;padding:9px 18px;min-height:40px;font-size:13px;background:transparent;border-color:var(--line);color:var(--brand)}
.offer-strip{margin:32px 0 12px;font-size:13px;color:var(--muted);line-height:1.8}
.offer-strip b{color:var(--brand)}
.spec{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px;border-top:1px solid var(--line);padding-top:28px;margin-top:48px}
.spec dt{font-size:11px;color:var(--muted);margin-bottom:6px}
.spec dd{font-size:13px;line-height:1.6}
.howto{font-size:13px;color:var(--muted);max-width:65em;margin-top:24px;line-height:1.9}
.howto b{color:var(--ink)}
.howto a,.fine a,.terms a,.privacy a,.faq-list a{color:var(--brand);text-decoration:underline;text-underline-offset:3px}
.more-topics{font-size:12px;color:var(--muted);margin-top:20px;display:flex;gap:9px;align-items:center}
.dot-live{width:5px;height:5px;background:var(--brand);border-radius:50%;flex:none}
/* Actual work is the centerpiece of the marking chapter. */
.marking{padding-top:112px}
.marking .head{max-width:780px}
.examples{max-width:1040px;margin:auto}
.journey{margin-top:64px;margin-bottom:72px}
.ex-label{font-size:12px;color:var(--brand);font-weight:500;margin-bottom:20px}
.journey>.ex-label{text-align:center}
.jr-stage{aspect-ratio:16/9;border-radius:20px;background:#193B2D}
.jr-bars{max-width:220px;margin:0 auto 16px}
.jr-bars i{height:2px;background:var(--line)}
.jr-bars i::after{background:var(--brand)}
.jr-caption{max-width:700px;margin:24px auto 0;grid-template-columns:32px 1fr auto}
.jr-caption h3{color:var(--ink);font-size:22px}
.jr-caption p:not(.jr-n){color:var(--muted);font-size:14px;line-height:1.7}
.jr-n{color:var(--brand)}
.jr-pause{color:var(--muted);border-color:var(--line);min-height:32px;font-size:12px}
.jr-more{text-align:center;margin-top:20px}
.jr-more a{color:var(--brand);font-size:12px}
.pillars{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:32px;margin:72px 0 104px}
.pillars span{font-size:11px;color:var(--muted);display:block;margin-bottom:16px}
.pillars b{font-size:20px;display:block;margin-bottom:10px;letter-spacing:-.02em}
.pillars p{font-size:13px;line-height:1.8;color:var(--muted)}
.ex-top{display:flex;flex-direction:column;align-items:center;gap:4px;margin-bottom:42px}
.ex-tabs{display:flex;position:relative;justify-content:center;gap:28px;border-bottom:1px solid var(--line);max-width:100%;overflow:auto;scrollbar-width:none}
.ex-tabs button{all:unset;box-sizing:border-box;position:relative;z-index:1;cursor:pointer;flex:none;padding:12px 0 16px;font-size:13px;line-height:1.4;color:var(--muted);min-height:44px}
.ex-tabs button[aria-selected="true"]{color:var(--brand);font-weight:600}
.ex-ind{position:absolute;top:auto;left:0;bottom:0;height:2px!important;background:var(--brand);border-radius:0}
.ex[hidden]{display:none}
.ex h3{font-size:32px;text-align:center;max-width:26em;margin:0 auto 36px}
.ex h3 em{font-style:normal;color:var(--brand)}
.ex-grid{display:grid;grid-template-columns:1fr 1fr;gap:48px;align-items:start}
.ex-ans figcaption,.ex-cap{font-size:12px;color:var(--muted);margin-bottom:16px}
.ex-ans img{width:100%;height:auto;border-radius:5px;background:#fff;padding:16px}
.ex-note{display:grid;gap:14px;font-size:15px;line-height:1.85}
.ex-note .ex-cap{margin:0}
.ex-note .math{padding:16px 20px;background:#FFFFFF80;border-radius:6px;font-size:14px;border-left:2px solid var(--line)}
.ex-note .key{padding-top:16px;border-top:1px solid var(--line);font-size:13px}
.key b{color:var(--brand);margin-right:8px}
.ex-take{text-align:center;font-size:16px;line-height:1.8;margin:32px auto 0;max-width:40em}
.ex-foot{font-size:11px;color:var(--muted);text-align:center;margin-top:20px}
.marking-grid{max-width:760px;margin:96px auto 0}
.plans>.kicker,.plans-title{text-align:center}
.plans-title{font-size:30px;margin-bottom:32px}
.plan-list{border-top:1px solid var(--line)}
.plan{display:grid;grid-template-columns:1fr auto;gap:6px 24px;align-items:center;padding:24px 0;border-bottom:1px solid var(--line)}
.plan h3{font-size:19px;line-height:1.4}
.plan .tag{margin:0 0 0 8px;font-size:10px;vertical-align:middle}
.plan .per{grid-column:1;font-size:12px;color:var(--muted)}
.plan .price{grid-column:2;grid-row:1 / 3;font-size:25px}
.plan-rule{font-size:12px;line-height:1.9;color:var(--muted);margin:24px 0}
.plans .fine{margin-top:20px}
.flow{margin-top:96px}
.flow>.kicker,.flow>h3{text-align:center}
.flow>h3{font-size:28px;margin-bottom:40px}
.flow-steps{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:28px}
.flow-steps span{font-size:20px;color:var(--brand);display:block;margin-bottom:18px}
.flow-steps b{display:block;font-size:14px;line-height:1.6;margin-bottom:10px}
.flow-steps p{font-size:12px;line-height:1.8;color:var(--muted);overflow-wrap:anywhere}
.flow-steps a{color:var(--brand)}
/* Long reading remains left aligned and deliberately narrow. */
.about .section-subtitle br{display:none}
.about-copy{max-width:640px;margin:auto;display:grid;gap:24px;font-size:18px;line-height:1.95;color:var(--muted)}
.about-copy p:nth-child(2){color:var(--ink)}
.about-copy .quiet{font-size:15px;margin-top:8px;color:var(--brand)}
.faq{padding-top:80px;padding-bottom:100px}
.faq .section-subtitle{font-size:17px;font-weight:400;color:var(--muted);margin-top:14px}
.faq-list{max-width:760px;margin:auto}
.faq-list details{border-bottom:1px solid var(--line)}
summary{list-style:none;cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:24px;min-height:64px;padding:20px 0;font-size:15px;font-weight:500;line-height:1.6}
summary::-webkit-details-marker{display:none}
.plus{width:12px;height:12px;position:relative;flex:none}
.plus::before,.plus::after{content:"";position:absolute;top:50%;left:0;width:12px;height:1px;background:currentColor;transition:transform var(--motion-disclosure)}
.plus::after{transform:rotate(90deg)}
details[open] .plus::after{transform:rotate(0)}
.faq-list p{font-size:14px;line-height:1.9;color:var(--muted);padding:0 24px 24px 0}
.terms{margin-top:36px;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.terms summary{font-size:13px}
.terms ul{max-width:800px;display:grid;gap:14px;padding:0 0 24px}
.terms li{font-size:12px;line-height:1.9;color:var(--muted)}
.terms-more{font-size:12px;color:var(--muted);margin-bottom:24px}
.privacy{padding-bottom:48px}
.privacy .wrap{max-width:760px}
.privacy .terms{margin-top:0}
.privacy-body{display:grid;gap:12px;font-size:12px;line-height:1.9;color:var(--muted);padding-bottom:24px}
.contact{padding:80px 0 120px;text-align:center}
.contact h2{font-size:clamp(30px,3.6vw,44px)}
.contact p{font-size:17px;color:var(--muted);margin:20px 0 28px}
.footer{border-top:1px solid var(--line);font-size:12px;color:var(--muted)}
.footer-top{display:grid;grid-template-columns:1fr 2fr;gap:64px;padding:48px 0}
.footer-mark{display:flex;align-items:center;gap:12px;font-size:13px;color:var(--ink);align-self:start}
.footer-mark img{width:32px;height:32px;border-radius:7px}
.footer-cols{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:32px}
.footer-cols>div{display:flex;flex-direction:column;gap:10px;min-width:0}
.footer-h{font-size:12px;color:var(--ink);font-weight:600;margin-bottom:6px}
.footer-cols a{overflow-wrap:anywhere}
.footer-base{display:flex;flex-wrap:wrap;gap:12px 24px;padding:24px 0;border-top:1px solid var(--line);font-size:10px}
/* Native notes viewer keeps its own contrast and focus handling. */
.viewer{border:0;padding:0;margin:0;width:100vw;height:100dvh;max-width:none;max-height:none;background:#142A21F5;color:var(--on-deep)}
.viewer[open]{display:flex;flex-direction:column}
.viewer::backdrop{background:#0006}
.viewer-open{overflow:hidden}
.viewer-bar{display:flex;justify-content:space-between;align-items:center;padding:16px 24px;padding-top:max(16px,env(safe-area-inset-top));font-size:14px}
.viewer-close{all:unset;cursor:pointer;padding:10px 4px;min-height:24px}
.viewer-stage{display:flex;align-items:center;justify-content:center;gap:20px;flex:1;min-height:0;padding:0 16px 24px}
.viewer-stage img{max-width:min(100%,820px);max-height:100%;object-fit:contain;border-radius:4px}
.viewer-nav{all:unset;cursor:pointer;display:grid;place-items:center;width:44px;height:44px;flex:none;background:#ffffff1a;border-radius:50%;font-size:28px}
.noscript{padding:24px;font-size:14px}
/* Calm motion: no hidden chapter, no decorative reveal delays. */
.js .reveal,.js .reveal.visible{opacity:1;transform:none;transition:none}
.hero .lede,.hero .actions,.hero-note{animation:none}
@media(hover:hover) and (pointer:fine){
  .btn:hover{background:var(--brand-hover);border-color:var(--brand-hover)}
  .btn-ghost:hover,.bundle .btn:hover,.btn-line:hover,.btn-light:hover{background:var(--mint);color:var(--brand);border-color:transparent}
  .link:hover,.course .go:hover,.nav a:hover,.footer a:hover{color:var(--brand);text-decoration:underline;text-underline-offset:4px}
  .notes-rail button:hover{box-shadow:0 8px 24px -14px #142A2155}
}
@media(max-width:960px){
  .header-in{gap:20px}.nav{gap:20px}.brand{font-size:13px}
  .section{padding:100px 0}.fit{padding:64px 0 80px}.hero{padding-top:60px}
  .fit-list{gap:28px}.fit-list strong{font-size:20px}
  .courses{gap:32px}.course h3{font-size:21px}
  .sample-caption{grid-template-columns:1fr;gap:12px}.sample-caption-copy{justify-self:start;max-width:58em}
  .pillars{grid-template-columns:repeat(2,minmax(0,1fr));gap:36px 48px}
  .flow-steps{grid-template-columns:repeat(3,minmax(0,1fr));gap:32px}
  .ex-tabs{gap:20px}.ex-tabs button{font-size:12px}
  .footer-top{grid-template-columns:1fr;gap:36px}
}
@media(max-width:700px){
  html{scroll-padding-top:104px}
  .header-in{min-height:0;flex-wrap:wrap;gap:0 12px;padding-top:10px;width:calc(100% - 40px)}
  .brand{font-size:12px;gap:8px}.brand img{width:24px;height:24px}
  .header-buy{margin-left:auto;font-size:11px;padding:7px 13px;min-height:32px}
  .nav{order:3;width:100%;margin:4px 0 0;justify-content:center;gap:28px;overflow-x:auto;scrollbar-width:none;font-size:12px}
  .nav a{min-height:42px;flex:none}.nav a[aria-current]::after{bottom:3px}
  .hero{padding-top:44px}.hero .kicker{font-size:12px;margin-bottom:18px}
  .hero h1{font-size:clamp(33px,8.5vw,50px)}
  .hero .lede{font-size:16px;max-width:22em;margin-top:20px}
  .hero .actions{margin-top:24px;gap:4px}.btn{font-size:14px;padding:10px 20px;min-height:44px}
  .hero-note{font-size:10px;max-width:29em;margin-top:20px}
  .hero-material{margin-top:44px;width:114%;margin-left:-7%;aspect-ratio:1.9}
  .hero-sheet{width:35%}.hero-sheet-left{left:3%;top:9%}.hero-sheet-back{right:3%;top:9%}.hero-sheet-front{width:38%;left:31%}
  .section{padding:80px 0}.head{margin-bottom:36px}.head h2{font-size:36px;line-height:1.2}
  .head .section-subtitle{font-size:20px;margin-top:16px}
  .head>p:not(.section-subtitle){font-size:15px;line-height:1.85;margin-top:18px}
  .fit{padding-top:56px;padding-bottom:48px}.fit .head{margin-bottom:32px}
  .fit-list{grid-template-columns:1fr;gap:32px;max-width:380px;margin:auto}
  .fit-list li{position:relative;padding-left:38px;text-align:left}
  .fit-n{position:absolute;left:0;top:2px;width:23px;height:23px;line-height:21px;font-size:10px;margin:0}
  .fit-list p{font-size:13px}.fit-list strong{font-size:20px;margin-top:5px;max-width:15em}
  .sample .head{margin-bottom:32px}.sample .head .section-subtitle{font-size:20px}
  .player{border-radius:10px}.player-label{left:12px;bottom:12px;font-size:11px;padding:6px 10px;gap:8px}.player-label small{font-size:10px}
  .play{width:44px;height:44px;right:12px;bottom:12px}.play svg{width:18px}
  .sample-caption{margin-top:12px;gap:8px}.sample-links{gap:20px}.link{font-size:12px;min-height:40px}
  .sample-caption-copy .fine{font-size:10px;line-height:1.8}
  .notes{margin-top:52px}.notes-head{align-items:start;flex-direction:column;gap:10px;margin-bottom:24px}.notes-head h3{font-size:20px}
  .notes-head .kicker{font-size:11px}.notes-meta{font-size:11px}
  .notes-rail{grid-template-columns:none;grid-auto-flow:column;grid-auto-columns:58%;gap:16px;overflow-x:auto;scroll-snap-type:x mandatory;margin-inline:calc(-1 * var(--gutter));padding:2px var(--gutter) 18px;scroll-padding-inline:var(--gutter);scrollbar-width:none}
  .notes-rail li{scroll-snap-align:start}
  #courses .head .section-subtitle{font-size:20px}
  .courses{grid-template-columns:1fr;gap:36px;margin-top:44px}
  .course{display:grid;grid-template-columns:80px minmax(0,1fr);column-gap:24px;row-gap:6px;align-items:start;padding-bottom:30px;border-bottom:1px solid var(--line)}
  .cover{grid-column:1;grid-row:1 / span 4;align-self:start;justify-self:center;width:78px;height:106px;margin:8px 0 0;padding:10px 9px 10px 14px}.cover small{font-size:7px}.cover span{font-size:13px}
  .course>div:nth-child(2){grid-column:2}.course h3{font-size:21px}.course .zh{font-size:11px}.tag{font-size:10px;margin-top:6px}
  .course .blurb{grid-column:2;font-size:13px;min-height:0;margin:8px 0 0;line-height:1.75}
  .course .price{grid-column:2;font-size:24px;margin-top:6px;padding:0}
  .course .go{grid-column:2;margin:0;font-size:12px;min-height:36px}
  .bundles{grid-template-columns:1fr;gap:30px;margin-top:36px;padding-top:0;border:0}
  .bundle{padding-bottom:28px;border-bottom:1px solid var(--line)}
  .bundle-tag{font-size:18px}.bundle .price{font-size:27px}.bundle .btn{font-size:12px;padding:8px 16px;min-height:38px}
  .offer-strip{font-size:12px;margin-top:24px}.spec{grid-template-columns:1fr;gap:16px;padding-top:24px;margin-top:32px}.spec>div{display:flex;justify-content:space-between;gap:24px}.spec dt{margin:0}.spec dd{text-align:right;font-size:12px;max-width:20em}
  .howto{font-size:12px}.more-topics{font-size:11px;align-items:start}.dot-live{margin-top:8px}
  .journey{margin:36px 0 48px}.jr-stage{aspect-ratio:4/5;border-radius:12px}.jr-bars{max-width:160px;margin-bottom:12px}
  .jr-caption{grid-template-columns:24px 1fr auto;gap:10px;margin-top:20px}.jr-caption h3{font-size:19px}.jr-caption p:not(.jr-n){font-size:12px}.jr-n{font-size:11px;padding-top:4px}.jr-pause{padding:5px 9px;font-size:10px}
  .pillars{gap:28px 24px;margin:48px 0 64px}.pillars span{font-size:10px;margin-bottom:10px}.pillars b{font-size:18px;margin-bottom:8px}.pillars p{font-size:12px}
  .ex-top{align-items:stretch;margin-bottom:28px}.ex-top .ex-label{text-align:center}.ex-tabs{justify-content:flex-start;gap:22px;margin-right:calc(-1 * var(--gutter));padding-right:var(--gutter)}
  .ex h3{font-size:25px;margin-bottom:28px}.ex-grid{grid-template-columns:1fr;gap:28px}.ex-ans img{padding:12px}.ex-note{font-size:14px;gap:12px}.ex-note .math{font-size:13px;padding:14px}.ex-take{font-size:14px;margin-top:24px}
  .marking-grid{margin-top:64px}.plans-title{font-size:26px}.plan .price{font-size:23px}.plans .actions{flex-direction:column;align-items:stretch}
  .flow{margin-top:64px}.flow>h3{font-size:24px;margin-bottom:32px}.flow-steps{grid-template-columns:1fr;gap:24px}.flow-steps li{position:relative;padding-left:36px}.flow-steps span{position:absolute;left:0;top:0;font-size:18px}.flow-steps b{font-size:14px;margin-bottom:5px}.flow-steps p{font-size:12px}
  .about-copy{font-size:16px;gap:20px}.about .section-subtitle br{display:block}.about-copy .quiet{font-size:14px}
  .faq{padding:64px 0}.faq-list summary{font-size:14px;min-height:60px}.faq-list p{font-size:13px}
  .contact{padding:64px 0 88px}.contact h2{font-size:30px}.contact p{font-size:15px}.contact .actions{gap:8px}
  .footer-top{padding:36px 0;gap:32px}.footer-cols{grid-template-columns:1fr 1fr;gap:28px}.footer-cols>div:nth-child(2){grid-column:1 / -1;order:3}.footer-base{font-size:10px}
  .viewer-stage{padding:0 8px 16px}.viewer-nav{display:none}.viewer-bar{padding-inline:16px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}.js .reveal{transform:none!important;opacity:1!important}.hero *{animation:none!important}
  .jr-stage *{transition:opacity var(--motion-fade)!important}.jr-mail-body img{transform:none!important}
  .btn:active,.notes-rail button:active{transform:none!important}
}
@media(prefers-reduced-transparency:reduce){.header{background:var(--paper);backdrop-filter:none;-webkit-backdrop-filter:none}}
@media(prefers-contrast:more){:root{--muted:#414A42;--line:#9FA99E}.header{background:var(--paper)}}