:root {
  color-scheme: light;
  --ink: #2f392f;
  --muted: #56624e;
  --green: #41694b;
  --green-dark: #2f5138;
  --leaf: #e6edda;
  --cream: #fbf8ef;
  --paper: #fffefa;
  --coral: #d76d4a;
  --coral-light: #f8dfd1;
  --gold: #dfad4e;
  --line: #e6e4d8;
  --shadow: 0 18px 50px rgba(58, 70, 47, .08);
  font-family: "Aptos", "Segoe UI", "Microsoft YaHei UI", "Noto Sans SC", sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  background: var(--cream);
  color: var(--ink);
}

* { box-sizing: border-box; }
body { margin: 0; min-width: 320px; background: var(--cream); }
button, a { font: inherit; }
button { color: inherit; }
a { color: inherit; }
[hidden] { display: none !important; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
.skip-link { position: absolute; left: 1rem; top: -6rem; z-index: 20; padding: .8rem 1rem; background: #fff; border-radius: 0 0 12px 12px; }
.skip-link:focus { top: 0; }
:focus-visible { outline: 3px solid #9a6211; outline-offset: 3px; }

.site-header { min-height: 76px; padding: 12px clamp(16px, 4vw, 56px); display: flex; justify-content: space-between; align-items: center; border-bottom: 1px solid rgba(95, 112, 76, .12); background: rgba(255, 254, 250, .8); }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; }
.brand-mark { width: 42px; height: 42px; display: grid; place-items: center; border-radius: 15px; background: #e9f0dc; color: var(--green); font-size: 28px; }
.brand strong, .brand small { display: block; }
.brand strong { font-size: 16px; letter-spacing: .03em; }
.brand small { margin-top: 2px; color: var(--muted); font-size: 11px; }
.header-actions { display: flex; gap: 4px; }
.quiet-button, .back-link { min-height: 48px; display: inline-flex; align-items: center; justify-content: center; padding: 8px 12px; border: 0; border-radius: 12px; color: #53634d; background: transparent; cursor: pointer; text-decoration: none; }
.quiet-button:hover, .back-link:hover { background: #edf1e6; }
.page-shell { width: min(1160px, calc(100% - 40px)); margin: 0 auto; }

.home-screen { padding: clamp(28px, 5vw, 56px) 0 38px; display: grid; grid-template-columns: 1fr .9fr; gap: 28px 54px; align-items: center; }
.hero-copy { padding: 10px 0; }
.eyebrow { margin: 0 0 14px; color: #56624e; font-size: 12px; font-weight: 750; letter-spacing: .11em; text-transform: uppercase; }
.eyebrow-dot { width: 8px; height: 8px; display: inline-block; margin-right: 8px; border-radius: 50%; background: var(--coral); vertical-align: 1px; }
h1, h2, p { margin-top: 0; }
.hero-copy h1, .finish-screen h1 { margin: 0; font-size: clamp(38px, 5.3vw, 62px); line-height: 1.15; letter-spacing: -.045em; font-weight: 760; }
.hero-copy h1 span, .finish-screen h1 span { color: var(--green); }
.intro { max-width: 520px; margin: 19px 0 18px; color: #5d6758; font-size: 17px; line-height: 1.8; }
.promise-list { display: grid; gap: 9px; margin: 0 0 23px; padding: 0; list-style: none; color: #56634f; font-size: 14px; }
.promise-list li { display: flex; align-items: center; gap: 9px; }
.promise-list li span { width: 21px; height: 21px; display: grid; place-items: center; border-radius: 50%; background: #e4edd8; color: var(--green); font-size: 13px; font-weight: 800; }
.primary-button, .secondary-button { min-height: 50px; display: inline-flex; align-items: center; justify-content: center; gap: 12px; padding: 11px 18px; border-radius: 14px; font-weight: 700; text-decoration: none; cursor: pointer; transition: background .16s ease, transform .16s ease; }
.primary-button { border: 1px solid var(--green); background: var(--green); color: white; box-shadow: 0 5px 14px rgba(51, 91, 59, .16); }
.primary-button:hover:not(:disabled) { background: var(--green-dark); transform: translateY(-1px); }
.secondary-button { border: 1px solid #d9decf; background: #fffefa; color: #425d43; }
.secondary-button:hover:not(:disabled) { background: #f2f5eb; }
button:disabled { cursor: not-allowed; opacity: .48; transform: none; box-shadow: none; }
.start-button { min-height: 54px; padding-inline: 23px; }
.start-button span { font-size: 19px; }
.privacy-note { max-width: 430px; margin: 12px 0 0; color: #56624e; font-size: 11px; line-height: 1.6; }

.hero-art { position: relative; min-height: 345px; overflow: hidden; isolation: isolate; border-radius: 38% 38% 24px 24px; background: linear-gradient(#eaf1df 0%, #f5f1dc 62%, #e5eed7 100%); }
.sun { position: absolute; width: 81px; height: 81px; top: 35px; right: 50px; border-radius: 50%; background: #f1c66e; box-shadow: 0 0 0 12px rgba(241,198,110,.15); }
.cloud { position: absolute; width: 68px; height: 24px; border-radius: 20px; background: rgba(255,255,255,.82); }
.cloud::before, .cloud::after { content: ""; position: absolute; bottom: 6px; border-radius: 50%; background: inherit; }
.cloud::before { left: 12px; width: 28px; height: 29px; }
.cloud::after { right: 10px; width: 22px; height: 21px; }
.cloud-one { left: 11%; top: 75px; transform: scale(.8); }
.cloud-two { right: 17%; top: 122px; transform: scale(.55); opacity: .75; }
.hill { position: absolute; bottom: -47px; border-radius: 50% 50% 0 0; }
.hill-back { left: -20%; width: 150%; height: 185px; background: #d2e2bd; transform: rotate(-7deg); }
.hill-front { right: -25%; bottom: -78px; width: 120%; height: 170px; background: #afc99b; transform: rotate(8deg); }
.fox { position: absolute; width: min(58%, 235px); height: auto; right: 25%; bottom: 42px; z-index: 2; filter: drop-shadow(0 7px 2px rgba(89, 100, 68, .12)); }
.flower { position: absolute; z-index: 3; color: #e58b78; text-shadow: 0 2px #fff1d3; }
.flower-one { bottom: 33px; left: 20%; font-size: 33px; }
.flower-two { bottom: 75px; right: 9%; color: #e6b848; font-size: 25px; }
.flower-three { bottom: 18px; right: 28%; color: #fff0c2; font-size: 20px; }
.art-caption { position: absolute; z-index: 4; left: 50%; top: 18px; transform: translateX(-50%); display: flex; align-items: center; gap: 8px; padding: 9px 12px; border: 1px solid rgba(255,255,255,.8); border-radius: 14px; background: rgba(255,254,250,.8); color: #485541; font-size: 12px; font-weight: 750; }
.art-caption small { color: #56624e; font-size: 10px; font-weight: 500; }
.caption-flower { color: #df896f; font-size: 22px; }
.station-preview { grid-column: 1/-1; display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.station-preview article { min-height: 79px; display: flex; align-items: center; gap: 12px; padding: 14px 17px; border: 1px solid #e7e5d9; border-radius: 18px; background: rgba(255,254,250,.82); }
.station-icon { width: 37px; height: 37px; display: grid; place-items: center; flex: 0 0 auto; border-radius: 13px; background: #eff2e8; color: var(--green); }
.icon-pebble { font-size: 18px; }.icon-sun { color: #c58d28; }.icon-story { color: #cc765c; }
.station-preview article strong, .station-preview article small { display: block; }
.station-preview article strong { font-size: 13px; }
.station-preview article small { margin-top: 3px; color: #56624e; font-size: 11px; }
.station-number { margin-left: auto; color: #56624e; font-size: 12px; font-weight: 750; }

.site-footer { display: flex; justify-content: space-between; gap: 10px; padding: 18px 0 25px; border-top: 1px solid #e6e4d8; color: #56624e; font-size: 11px; }
.site-footer a { color: #627553; }

.lesson-screen { padding: 18px 0 28px; }
.lesson-topline { display: flex; justify-content: space-between; align-items: center; margin-bottom: 9px; }
.lesson-duration { color: #56624e; font-size: 12px; }
.station-nav { display: grid; grid-template-columns: repeat(3, 1fr); gap: 9px; padding: 7px; border: 1px solid #e6e4d8; border-radius: 18px; background: #f4f3e9; }
.station-nav button { min-height: 54px; display: flex; justify-content: center; align-items: center; gap: 9px; border: 1px solid transparent; border-radius: 13px; background: transparent; color: #56624e; cursor: pointer; }
.station-nav button span { color: #56624e; font-size: 11px; font-weight: 800; }
.station-nav button b { font-size: 13px; }
.station-nav button[aria-current="step"] { border-color: #e1e4d5; background: #fffefa; color: var(--green-dark); box-shadow: 0 4px 12px rgba(43,56,36,.06); }
.station-nav button[aria-current="step"] span { color: #8b4b32; }
.progress-row { display: flex; align-items: center; gap: 15px; margin: 15px 4px 20px; color: #56624e; font-size: 12px; }
.progress-track { height: 6px; flex: 1; overflow: hidden; border-radius: 10px; background: #e4e7da; }
.progress-track > span { display: block; width: 0; height: 100%; border-radius: inherit; background: linear-gradient(90deg, #729260, #e3b851); transition: width .25s ease; }
.lesson-heading { display: flex; justify-content: space-between; align-items: center; margin-bottom: 17px; }
.lesson-heading .eyebrow { margin-bottom: 5px; }
.lesson-heading h1 { margin-bottom: 5px; font-size: clamp(26px, 4vw, 36px); letter-spacing: -.03em; }
.lesson-heading p:last-child { margin-bottom: 0; color: #56624e; font-size: 14px; }
.momo-bubble { width: 54px; height: 54px; display: grid; place-items: center; position: relative; border-radius: 20px; background: #f8e8dc; font-size: 27px; }
.bubble-dot { position: absolute; right: 7px; bottom: 7px; width: 10px; height: 10px; border: 2px solid white; border-radius: 50%; background: #729260; }
.activity-panel { display: grid; grid-template-columns: .76fr 1.24fr; align-items: start; gap: 17px; }
.prompt-card, .play-card { border: 1px solid #e7e5da; border-radius: 21px; background: var(--paper); box-shadow: var(--shadow); }
.prompt-card { padding: 22px; background: linear-gradient(145deg,#fffefa,#f4f6eb); }
.prompt-badge { display: inline-flex; align-items: center; min-height: 25px; margin-bottom: 12px; padding: 3px 9px; border-radius: 20px; background: #e8efdf; color: #4d6a49; font-size: 11px; font-weight: 750; }
.prompt-card h2 { margin-bottom: 8px; font-size: 21px; line-height: 1.5; letter-spacing: -.02em; }
.prompt-card h2 strong { color: var(--coral); font-size: 28px; }
.prompt-card > p { margin-bottom: 16px; color: #56624e; font-size: 13px; line-height: 1.65; }
.play-card { padding: 21px; }
.play-card-heading { display: flex; justify-content: space-between; align-items: center; gap: 8px; margin-bottom: 14px; color: #53634e; font-size: 13px; font-weight: 750; }
.play-card-heading span:last-child { color: #5d594f; font-size: 12px; font-weight: 600; text-align: right; }
.number-picker { display: flex; flex-wrap: wrap; gap: 6px; }
.number-picker button { width: 48px; min-height: 48px; border: 1px solid #dfe4d7; border-radius: 12px; background: #fffefa; color: #516149; font-size: 14px; font-weight: 750; cursor: pointer; }
.number-picker button[aria-pressed="true"] { border-color: #58784f; background: #e8efdf; color: #31553a; box-shadow: inset 0 0 0 1px #58784f; }
.number-picker button:hover { background: #f1f5e9; }
.ten-frame { width: min(100%, 396px); display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 8px; margin: 0 auto; }
.frame-slot { position: relative; min-width: 48px; min-height: 51px; aspect-ratio: 1; display: grid; place-items: center; padding: 0; border: 1px solid #768268; border-radius: 15px; background: #f6f7ee; cursor: pointer; }
.frame-slot:hover:not(:disabled) { border-color: #56624e; background: #edf2e5; }
.frame-slot .counter { width: 54%; height: 54%; display: block; border-radius: 50%; background: transparent; transition: transform .12s ease, background .12s ease; }
.frame-slot.is-start .counter { background: #62875e; box-shadow: inset -3px -4px 0 rgba(39,81,45,.12); }
.frame-slot.is-added .counter { background: #ae593d; box-shadow: inset -3px -4px 0 rgba(72,35,25,.18); }
.frame-slot.is-removed .counter { border: 2px dashed #8b5142; background: #f2d8ce; }
.frame-slot.is-removed::after { content: "×"; position: absolute; display: grid; place-items: center; width: 23px; height: 23px; border: 2px solid #8b5142; border-radius: 50%; color: #733f34; background: #fff9f4; font-size: 18px; font-weight: 800; line-height: 1; }
.frame-slot.is-selected-remove { outline: 3px solid #8b5142; outline-offset: -4px; }
.frame-slot:disabled { cursor: default; opacity: 1; }
.frame-slot .slot-number { position: absolute; right: 3px; bottom: 2px; color: #56624e; font-size: 9px; }
.equation-line, .bond-equation, .story-equation { margin: 15px auto 7px; color: #556a4d; text-align: center; font-size: 19px; font-weight: 750; letter-spacing: .04em; }
.bond-equation { display: inline-flex; min-height: 45px; align-items: center; justify-content: center; margin: 4px 0 0; padding: 6px 14px; border: 1px dashed #c5d0b8; border-radius: 14px; background: #fbfcf7; font-size: 22px; }
.feedback { min-height: 26px; margin: 10px 0 13px; color: #56624e; text-align: center; font-size: 13px; line-height: 1.6; }
.feedback.success { color: #3f7046; font-weight: 700; }
.feedback.gentle { color: #725139; }
.panel-actions { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; margin-top: 15px; }
.panel-actions .primary-button, .panel-actions .secondary-button { min-width: 134px; }
.scaffold-actions { display: flex; justify-content: center; flex-wrap: wrap; gap: 2px 10px; }
.text-button { min-height: 48px; padding: 8px 10px; border: 0; border-radius: 12px; background: transparent; color: #58734c; font-size: 12px; font-weight: 700; text-decoration: underline; text-decoration-color: #b9c7ac; text-underline-offset: 3px; cursor: pointer; }
.text-button:hover { background: #f2f5eb; }
.notebook-strip { display: flex; align-items: center; gap: 12px; margin-top: 16px; padding: 13px 16px; border: 1px solid #e9e2ca; border-radius: 16px; background: #fff9e9; color: #56624e; }
.notebook-strip p { margin: 0; flex: 1; font-size: 12px; line-height: 1.6; }
.notebook-strip strong { color: #5d6046; }
.notebook-icon, .notebook-mark { color: #c49238; font-size: 19px; }
.notebook-mark { opacity: .55; }

.story-prompt-card { grid-column: 1; }
.story-title-row { display: flex; align-items: flex-start; gap: 12px; }
.story-title-row h2 { margin-bottom: 5px; }
.story-picture { width: 45px; min-width: 45px; height: 45px; display: grid; place-items: center; border-radius: 15px; background: #f8e7d9; font-size: 26px; }
.story-title-row p { color: #606e59; font-size: 15px; line-height: 1.8; }
.story-equation { min-height: 40px; padding: 7px 12px; border-radius: 12px; background: #f1f4e9; font-size: 18px; }
.story-answer-picker { justify-content: center; margin-top: 12px; }
.story-answer-picker button { min-height: 48px; width: 48px; }
.removal-legend { margin: 4px 0 0; color: #56624e; text-align: center; font-size: 12px; }
.demo-frame { grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 4px; width: min(100%, 396px); justify-content: center; margin-block: 20px; }
.demo-counter { width: 100%; min-width: 48px; min-height: 48px; aspect-ratio: 1; display: grid; place-items: center; padding: 0; border: 1px solid #768268; border-radius: 12px; background: #f6f7ee; color: #41694b; font-size: 28px; }
button.demo-counter { cursor: pointer; }
.demo-counter.is-added { color: #ae593d; }
.demo-counter { font-size: 0; }
.demo-counter.is-start::before, .demo-counter.is-added::before { content: ''; width: 54%; height: 54%; border-radius: 50%; background: #62875e; }
.demo-counter.is-added::before { background: #ae593d; }

.finish-screen { max-width: 850px; margin: 0 auto; padding: clamp(48px, 9vw, 94px) 0 64px; text-align: center; }
.finish-sparkle { width: 66px; height: 66px; display: grid; place-items: center; margin: 0 auto 20px; border-radius: 24px; background: #f8eac6; color: #c49334; font-size: 35px; }
.finish-screen .eyebrow { margin-bottom: 11px; }
.finish-screen h1 { font-size: clamp(36px, 5vw, 56px); }
.finish-copy { max-width: 580px; margin: 17px auto 25px; color: #56624e; font-size: 15px; line-height: 1.8; }
.recap-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin: 24px 0; text-align: left; }
.recap-grid article { min-height: 132px; padding: 17px; border: 1px solid #e7e5d9; border-radius: 17px; background: var(--paper); }
.recap-grid article span, .recap-grid strong, .recap-grid small { display: block; }
.recap-grid article span { margin-bottom: 12px; color: #8b5142; font-size: 11px; font-weight: 800; }
.recap-grid strong { font-size: 14px; }
.recap-grid small { margin-top: 7px; color: #788172; font-size: 12px; line-height: 1.6; }
.next-practice { max-width: 610px; margin: 0 auto 20px; padding: 13px 18px; border-radius: 14px; background: #edf2e5; color: #5c6e51; font-size: 13px; line-height: 1.7; }
.finish-actions { align-items: center; }
.guide-link { min-width: 164px; }
.toast { position: fixed; right: 16px; bottom: 16px; z-index: 10; max-width: min(380px, calc(100vw - 32px)); padding: 13px 16px; border: 1px solid #d7dfca; border-radius: 14px; background: #fffefa; color: #465e42; box-shadow: var(--shadow); font-size: 13px; }

@media (max-width: 780px) {
  .page-shell { width: min(100% - 28px, 620px); }
  .home-screen { grid-template-columns: 1fr; gap: 21px; padding-top: 30px; }
  .hero-copy h1 { font-size: clamp(38px, 9vw, 55px); }
  .hero-art { min-height: 295px; }
  .fox { width: min(58%, 220px); right: 22%; }
  .station-preview { gap: 8px; }
  .station-preview article { min-height: 72px; gap: 8px; padding: 11px 9px; }
  .station-number { display: none; }
  .activity-panel { grid-template-columns: 1fr; }
  .prompt-card { padding: 18px; }
  .play-card { padding: 17px; }
  .story-prompt-card { grid-column: auto; }
}
@media (max-width: 500px) {
  .site-header { min-height: 68px; padding-inline: 12px; }
  .brand-mark { width: 36px; height: 36px; border-radius: 12px; font-size: 24px; }
  .brand strong { font-size: 14px; }
  .brand small { font-size: 10px; }
  .header-actions { gap: 0; }
  .quiet-button { min-height: 48px; padding-inline: 7px; font-size: 11px; }
  .home-screen { padding-top: 25px; }
  .intro { font-size: 15px; }
  .hero-art { min-height: 255px; border-radius: 42% 42% 20px 20px; }
  .station-preview { grid-template-columns: 1fr; }
  .station-preview article { min-height: 62px; padding-inline: 13px; }
  .station-number { display: block; }
  .lesson-topline { margin-bottom: 4px; }
  .back-link { min-height: 48px; padding-inline: 6px; font-size: 12px; }
  .station-nav { gap: 3px; padding: 4px; }
  .station-nav button { min-height: 51px; flex-direction: column; gap: 2px; }
  .station-nav button b { font-size: 11px; }
  .progress-row { margin-block: 12px 15px; }
  .lesson-heading { align-items: flex-start; }
  .lesson-heading p:last-child { max-width: 260px; font-size: 12px; }
  .momo-bubble { width: 45px; min-width: 45px; height: 45px; border-radius: 16px; font-size: 22px; }
  .prompt-card h2 { font-size: 18px; }
  .number-picker { gap: 5px; }
  .number-picker button { width: 48px; min-height: 48px; }
  .ten-frame { gap: 4px; }
  .frame-slot { min-width: 48px; min-height: 48px; border-radius: 12px; }
  .frame-slot .slot-number { display: none; }
  .play-card-heading { font-size: 12px; }
  .play-card-heading span:last-child { font-size: 11px; }
  .panel-actions { gap: 8px; }
  .panel-actions .primary-button, .panel-actions .secondary-button { flex: 1 1 130px; min-width: 0; padding-inline: 12px; }
  .story-title-row p { font-size: 14px; }
  .recap-grid { grid-template-columns: 1fr; }
  .recap-grid article { min-height: 0; }
  .site-footer { flex-direction: column; font-size: 10px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}