:root {
  --paper: #f2f4f0;
  --paper-light: #fafbf8;
  --ink: #19271e;
  --ink-soft: #647067;
  --blue: #315f42;
  --teal: #3f7654;
  --red: #8c691f;
  --gold: #c59c42;
  --control-bg: #315f42;
  --control-fg: #ffffff;
  --control-hover: #284d36;
  --reveal-bg: #e5c968;
  --reveal-fg: #19271e;
  --reveal-hover: #f0d983;
  --learning-new: #2168c4;
  --learning-new-bg: #e3efff;
  --learning-correct: #14733f;
  --learning-correct-bg: #dff5e7;
  --learning-incorrect: #b92f3b;
  --learning-incorrect-bg: #fde3e5;
  --learning-unsure: #965800;
  --learning-unsure-bg: #fff0c7;
  --grammar-time: #1769aa;
  --grammar-subject: #7046a8;
  --grammar-place: #087b83;
  --grammar-adverb: #a35d00;
  --grammar-modal: #8d3b76;
  --grammar-verb: #157442;
  --grammar-object: #b23b32;
  --grammar-complement: #b34c78;
  --grammar-modifier: #7a6300;
  --grammar-measure: #b85119;
  --grammar-connector: #4453a6;
  --grammar-particle: #606b63;
  --grammar-question: #a42b85;
  --grammar-greeting: #8a6300;
  --line: rgba(25, 51, 33, 0.16);
  --shadow: 0 24px 80px rgba(31, 53, 38, 0.12);
  --sans: "DM Sans", system-ui, sans-serif;
  --serif-sc: "Noto Serif SC", "Songti SC", serif;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --paper: #121713;
  --paper-light: #1d261f;
  --ink: #f2f5f1;
  --ink-soft: #adb7af;
  --blue: #a6ceb0;
  --teal: #9dc6a8;
  --red: #d2aa58;
  --gold: #8e7135;
  --control-bg: #a6ceb0;
  --control-fg: #121713;
  --control-hover: #c2dfc8;
  --reveal-bg: #d2aa58;
  --reveal-fg: #121713;
  --reveal-hover: #e6c470;
  --learning-new: #86baff;
  --learning-new-bg: #19395f;
  --learning-correct: #7fe0a6;
  --learning-correct-bg: #163c29;
  --learning-incorrect: #ff9ba4;
  --learning-incorrect-bg: #4c2026;
  --learning-unsure: #ffd071;
  --learning-unsure-bg: #4c3714;
  --grammar-time: #79bfff;
  --grammar-subject: #c7a3ff;
  --grammar-place: #72d9df;
  --grammar-adverb: #ffc164;
  --grammar-modal: #f0a2d5;
  --grammar-verb: #79dfa3;
  --grammar-object: #ff9e94;
  --grammar-complement: #ffa7ca;
  --grammar-modifier: #f0d475;
  --grammar-measure: #ffae73;
  --grammar-connector: #aeb6ff;
  --grammar-particle: #b8c3bb;
  --grammar-question: #ff9ce4;
  --grammar-greeting: #f3cf6f;
  --line: rgba(237, 244, 238, 0.14);
  --shadow: 0 28px 85px rgba(0, 0, 0, 0.34);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1.6;
  overflow-x: hidden;
}
button, input { font: inherit; }
button { color: var(--ink); }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
.mandarin-page[hidden] { display: none; }
.section-shell { width: min(1180px, calc(100% - 40px)); margin-inline: auto; }
.visually-hidden {
  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: fixed; top: 10px; left: 10px; z-index: 1000; padding: 10px 14px;
  background: var(--control-bg); color: var(--control-fg); transform: translateY(-150%);
}
.skip-link:focus { transform: translateY(0); }

.brand { display: inline-flex; gap: 12px; align-items: center; text-decoration: none; line-height: 1.1; }
.brand strong { display: block; font-size: 0.88rem; letter-spacing: 0.02em; }
.brand small { display: block; margin-top: 5px; color: var(--ink-soft); font-size: 0.72rem; }
.brand-mark {
  display: grid; place-items: center; width: 42px; height: 42px; background: transparent; color: white;
  font-family: var(--serif-sc); font-weight: 700; border: 0; border-radius: 50%;
  overflow: hidden; box-shadow: none;
}
.brand-mark img { width: 100%; height: 100%; display: block; object-fit: cover; }
.brand-mark.small { width: 36px; height: 36px; }
.hero { min-height: 650px; display: grid; grid-template-columns: .78fr 1.22fr; gap: 64px; align-items: center; padding-block: 70px; }
.eyebrow { margin: 0 0 16px; color: var(--teal); font-size: .75rem; font-weight: 700; letter-spacing: .14em; text-transform: uppercase; }
.hero h1, .section-heading h2, .closing-section h2 {
  margin: 0; font-family: var(--serif-sc); font-weight: 700; line-height: 1.05; letter-spacing: -0.045em;
}
.hero h1 { max-width: 740px; font-size: clamp(5rem, 10vw, 9rem); }
.hero h1 em { color: var(--red); font-style: normal; }
.hero-lede { max-width: 600px; margin: 30px 0 0; color: var(--ink-soft); font-size: clamp(1.05rem, 1.7vw, 1.28rem); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }
.section-menu { display: grid; grid-template-columns: repeat(2, minmax(130px, 1fr)); gap: 10px; margin-top: 32px; }
.section-menu a { display: flex; min-height: 58px; align-items: center; justify-content: center; border: 1px solid var(--line); border-radius: 8px; background: var(--paper-light); font-weight: 700; text-decoration: none; }
.section-menu a:hover, .section-menu a:focus-visible { border-color: var(--ink); background: var(--paper-light); }
.mandarin-section-menu {
  width: min(1000px, calc(100% - 40px));
  grid-template-columns: repeat(4, minmax(120px, 1fr));
  margin: 40px auto 0;
}
.mandarin-section-menu a[aria-current="page"] { border-color: var(--control-bg); background: var(--control-bg); color: var(--control-fg); }
.button {
  display: inline-flex; min-height: 50px; align-items: center; justify-content: center; padding: 0 22px;
  border: 1px solid var(--line); border-radius: 8px; font-weight: 700; text-decoration: none; cursor: pointer;
  transition: transform .2s ease, background .2s ease, border-color .2s ease;
}
.button:hover { transform: translateY(-2px); }
.button-primary { background: var(--control-bg); color: var(--control-fg); }
.button-primary:hover { background: var(--control-hover); color: var(--control-fg); }
.button-accent { border-color: var(--reveal-bg); background: var(--reveal-bg); color: var(--reveal-fg); }
.button-accent:hover { border-color: var(--reveal-hover); background: var(--reveal-hover); color: var(--reveal-fg); }
.button-quiet { background: transparent; border-color: var(--line); color: var(--ink); }
.button-quiet:hover { border-color: var(--ink); }
.hero-stats { display: flex; gap: 34px; margin: 48px 0 0; }
.hero-stats div { display: grid; gap: 2px; }
.hero-stats dt { font-family: var(--serif-sc); font-size: 1.65rem; font-weight: 700; }
.hero-stats dd { margin: 0; color: var(--ink-soft); font-size: .72rem; text-transform: uppercase; letter-spacing: .08em; }

.hero-phrase {
  position: relative; padding: clamp(32px, 5vw, 58px); background: var(--ink); color: white; border-radius: 28px 28px 28px 5px;
  box-shadow: var(--shadow);
}
.hero-phrase::before {
  content: ""; position: absolute; inset: 12px; border: 1px solid rgba(255,255,255,.14); border-radius: 20px 20px 20px 3px; pointer-events: none;
}
.seal {
  position: absolute; top: -24px; right: 30px; display: grid; place-items: center; width: 82px; height: 82px;
  border: 4px double var(--red); color: var(--red); background: var(--paper); font-family: var(--serif-sc);
  font-size: 1.1rem; font-weight: 900; writing-mode: vertical-rl; border-radius: 8px; transform: rotate(5deg);
}
.card-kicker { margin: 0 0 28px; color: #9fcfd0; font-size: .72rem; font-weight: 700; letter-spacing: .14em; text-transform: uppercase; }
.featured-hanzi { margin: 0; font-family: var(--serif-sc); font-size: clamp(2.8rem, 5vw, 5rem); line-height: 1.15; }
.featured-pinyin { margin: 18px 0 2px; color: #9fcfd0; font-size: 1.05rem; }
.featured-meaning { margin: 0; color: rgba(255,255,255,.65); }
.hero-phrase .progress-row { margin-top: 36px; }
.tone-line { display: flex; gap: 8px; margin: 36px 0; }
.tone { padding: 4px 8px; border-bottom: 3px solid; color: rgba(255,255,255,.72); font-size: .77rem; }
.tone-1 { border-color: #68c2e8; }.tone-2 { border-color: #69c290; }.tone-3 { border-color: #f1c75b; }.tone-4 { border-color: #ea7a6a; }
.progress-row { display: flex; justify-content: space-between; margin-bottom: 8px; color: rgba(255,255,255,.64); font-size: .76rem; }
.progress-row strong { color: white; }
.progress-track { height: 6px; overflow: hidden; background: rgba(255,255,255,.12); border-radius: 99px; }
.progress-track span { display: block; width: 0; height: 100%; background: var(--red); transition: width .4s ease; }

.lessons-section, .lesson-section, .study-section, .pronunciation-section, .vocab-section, .writing-section, .practice-section { padding-block: 84px; }
.section-heading { margin-bottom: 48px; }
.section-heading h2, .closing-section h2 { font-size: clamp(2.5rem, 5vw, 4.8rem); }
.compact-heading { margin-bottom: 26px; }
.compact-heading h2 { font-size: clamp(2.35rem, 4vw, 3.5rem); }
.lesson-heading { display: flex; align-items: center; justify-content: space-between; gap: 18px; }
.section-heading > p:last-child { max-width: 660px; color: var(--ink-soft); }
.split-heading { display: grid; grid-template-columns: 1.2fr .8fr; gap: 40px; align-items: end; }
.split-heading > p { margin: 0 0 8px; }

.lessons-section, .lesson-section { border-top: 1px solid var(--line); }
.lesson-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.lesson-list-card {
  position: relative; display: grid; min-height: 210px; align-content: end; overflow: hidden; border: 1px solid var(--line);
  border-radius: 22px; background: var(--paper-light); padding: 24px; color: var(--ink); text-decoration: none;
  transition: border-color .2s ease, box-shadow .2s ease, transform .2s ease;
}
.lesson-list-card:hover, .lesson-list-card:focus-visible { border-color: var(--control-bg); box-shadow: var(--shadow); outline: 3px solid color-mix(in srgb, var(--control-bg) 24%, transparent); outline-offset: 2px; transform: translateY(-3px); }
.lesson-list-card strong { position: relative; font: 700 clamp(1.55rem, 3vw, 2.4rem) var(--serif-sc); }
.lesson-list-card small { position: relative; margin-top: 4px; color: var(--ink-soft); font-weight: 700; }
.lesson-list-card b { position: absolute; right: 22px; bottom: 22px; display: grid; width: 38px; height: 38px; place-items: center; border-radius: 50%; background: var(--control-bg); color: var(--control-fg); }
.lesson-card-sample { position: absolute; top: -20px; right: 18px; color: color-mix(in srgb, var(--gold) 42%, transparent); font: 700 7.5rem/1 var(--serif-sc); }
.greeting-grid { display: grid; grid-template-columns: repeat(5, 1fr); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.greeting-card { display: flex; min-height: 165px; flex-direction: column; justify-content: center; padding: 22px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.greeting-card span, .lesson-feature span { color: var(--red); font-size: .68rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; }
.greeting-card strong { margin-top: 14px; font-family: var(--serif-sc); font-size: clamp(2rem, 3vw, 3.1rem); font-weight: 600; line-height: 1.15; }
.greeting-card small { margin-top: 8px; color: var(--teal); }
.greeting-card em { margin-top: 5px; color: var(--ink-soft); font-size: .76rem; font-style: normal; }
.lesson-feature-grid { display: grid; grid-template-columns: 1fr; gap: 14px; margin-top: 14px; }
.lesson-feature { min-height: 190px; padding: 28px; border-radius: 5px 22px 22px 22px; background: #e4ebe9; }
.lesson-feature strong { display: block; margin-top: 24px; font-family: var(--serif-sc); font-size: clamp(1.6rem, 2.6vw, 2.45rem); line-height: 1.45; }
.lesson-feature p { margin: 18px 0 0; color: var(--ink-soft); }
.lesson-feature small { display: block; margin-top: 8px; color: var(--ink-soft); }
.lesson-sound-focus { display: flex; gap: 18px; align-items: center; margin-top: 18px; padding: 18px; border: 1px solid var(--line); border-radius: 14px; }
.lesson-sound-focus > strong { flex: 0 0 auto; font-size: .76rem; letter-spacing: .08em; text-transform: uppercase; }
.lesson-sound-chips { display: flex; flex-wrap: wrap; gap: 8px; }
.lesson-sound-chips button { display: inline-flex; gap: 7px; align-items: center; min-height: 38px; padding: 7px 12px; border: 1px solid var(--line); border-radius: 999px; background: var(--paper-light); color: var(--ink); cursor: pointer; }
.lesson-sound-chips button strong { color: var(--red); }
.listening-card { background: #e9e1cf; }
.listening-card strong { font-family: var(--sans); font-size: 1.55rem; line-height: 1.3; }

.study-section { border-top: 1px solid var(--line); }
.study-layout { display: grid; grid-template-columns: minmax(0, 1fr) 340px; gap: 34px; align-items: stretch; }
.flashcard-wrap { min-width: 0; }
.flashcard {
  min-height: 350px; padding: 32px; display: flex; flex-direction: column; justify-content: space-between;
  background: var(--paper-light); border: 1px solid var(--line); border-radius: 22px; cursor: pointer; outline: none;
  box-shadow: 0 16px 50px rgba(20,38,58,.07); transition: border-color .2s ease, background .2s ease, box-shadow .2s ease, color .2s ease, transform .2s ease;
}
.flashcard:hover, .flashcard:focus-visible { border-color: var(--teal); transform: translateY(-3px); }
.flashcard.is-resolving { cursor: default; }
.flashcard.is-correct,.flashcard.is-complete { border: 2px solid var(--learning-correct); background: var(--learning-correct-bg); color: var(--learning-correct); box-shadow: 0 18px 42px color-mix(in srgb, var(--learning-correct) 24%, transparent); animation: flashcard-correct-pop .4s ease-out; }
.flashcard.is-incorrect { border: 2px solid var(--learning-incorrect); background: var(--learning-incorrect-bg); color: var(--learning-incorrect); box-shadow: 0 14px 34px color-mix(in srgb, var(--learning-incorrect) 19%, transparent); }
.flashcard.is-correct .flash-answer p,.flashcard.is-incorrect .flash-answer p,.flashcard.is-complete .flash-answer p { color: currentColor; }
.flashcard-topline { display: flex; justify-content: space-between; gap: 14px; color: var(--ink-soft); font-size: .76rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; }
.flashcard-meta { display: inline-flex; flex-wrap: wrap; align-items: center; justify-content: flex-end; gap: 9px; }
.learning-status { display: inline-flex; align-items: center; min-height: 26px; border: 1px solid currentColor; border-radius: 999px; padding: 3px 9px; font-size: .64rem; font-weight: 900; letter-spacing: .08em; }
.learning-status[data-state="new"] { background: var(--learning-new-bg); color: var(--learning-new); }
.learning-status[data-state="correct"] { background: var(--learning-correct-bg); color: var(--learning-correct); }
.learning-status[data-state="incorrect"] { background: var(--learning-incorrect-bg); color: var(--learning-incorrect); }
.flashcard-center { text-align: center; }
.flash-hanzi { margin: 0; font-family: var(--serif-sc); font-size: clamp(4.5rem, 10vw, 8.5rem); line-height: 1; }
.flashcard[data-front="pinyin"] .flash-hanzi { font-family: var(--sans); font-size: clamp(2.6rem, 7vw, 5rem); line-height: 1.12; }
.flashcard[data-front="english"] .flash-hanzi { font-family: var(--sans); font-size: clamp(2.15rem, 6vw, 4.25rem); line-height: 1.16; }
.flash-prompt { margin: 20px 0 0; color: var(--ink-soft); }
.flash-answer { min-height: 73px; margin-top: 16px; opacity: 0; transform: translateY(8px); transition: opacity .2s ease, transform .2s ease; }
.flashcard.revealed .flash-answer { opacity: 1; transform: translateY(0); }
.flashcard.revealed .flash-prompt { display: none; }
.flash-answer p { margin: 0; color: var(--teal); font-size: 1.15rem; }
.flash-answer strong { display: block; margin-top: 4px; font-size: 1.25rem; }
.flash-hint { color: var(--ink-soft); font-size: .72rem; text-align: center; }
.flash-actions { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; margin-top: 16px; }
.flash-actions .button { min-width: 140px; }
.flash-actions .button:disabled { cursor: not-allowed; opacity: .42; transform: none; }
.button.learning-correct { border-color: var(--learning-correct); background: var(--learning-correct-bg); color: var(--learning-correct); }
.button.learning-incorrect { border-color: var(--learning-incorrect); background: var(--learning-incorrect-bg); color: var(--learning-incorrect); }
.button.learning-correct:not(:disabled):hover,.button.learning-correct:not(:disabled):focus-visible { box-shadow: 0 8px 20px color-mix(in srgb, var(--learning-correct) 19%, transparent); }
.button.learning-incorrect:not(:disabled):hover,.button.learning-incorrect:not(:disabled):focus-visible { box-shadow: 0 8px 20px color-mix(in srgb, var(--learning-incorrect) 16%, transparent); }

@keyframes flashcard-correct-pop {
  0% { transform: scale(.985); }
  72% { transform: scale(1.025); }
  100% { transform: scale(1); }
}
.session-panel { padding: 28px; background: #e4ebe9; border-radius: 22px 4px 22px 22px; }
.session-panel h3 { margin: 0 0 28px; font-family: var(--serif-sc); font-size: 1.65rem; line-height: 1.25; }
.session-list { list-style: none; margin: 0 0 24px; padding: 0; border-top: 1px solid rgba(20,38,58,.14); }
.session-list li { display: flex; align-items: center; gap: 12px; padding: 13px 0; border-bottom: 1px solid rgba(20,38,58,.14); }
.session-list .session-number { display: grid; place-items: center; width: 25px; height: 25px; border: 1px solid var(--line); border-radius: 50%; font-size: .7rem; }
.session-list li.active .session-number { background: var(--control-bg); color: var(--control-fg); }
.session-list li.known { color: var(--teal); }
.session-list .session-empty { color: var(--teal); font-weight: 800; }
.flashcard-settings { display: grid; gap: 10px; margin: 6px 0 18px; padding-top: 16px; border-top: 1px solid rgba(20,38,58,.14); }
.flashcard-settings label { display: flex; align-items: center; gap: 9px; color: var(--ink); font-size: .82rem; font-weight: 750; cursor: pointer; }
.flashcard-settings input { width: 18px; height: 18px; margin: 0; accent-color: var(--control-bg); }
.flashcard-settings .flash-front-setting { justify-content: space-between; }
.flash-front-setting select { min-height: 44px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper-light); color: var(--ink); padding: 0 10px; font: 750 .8rem var(--sans); }
.known-words-panel { margin-top: 24px; padding: 26px; border: 1px solid var(--line); border-radius: 18px; background: var(--paper-light); }
.known-words-heading { display: flex; align-items: center; justify-content: space-between; gap: 18px; margin-bottom: 18px; }
.known-words-heading h3 { margin: 0; font-family: var(--serif-sc); font-size: 1.45rem; }
.known-words-heading strong { display: grid; min-width: 42px; height: 42px; place-items: center; border-radius: 50%; background: #f3d46b; color: #2a2415; }
.known-word-list { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 9px; }
.known-word-chip { display: grid; gap: 2px; min-width: 0; padding: 13px; border-radius: 10px; background: #fff0a8; color: #2d2a1d; }
.known-word-chip strong { font: 600 1.35rem var(--serif-sc); }
.known-word-chip span { font-size: .76rem; }
.known-word-chip small { overflow: hidden; color: #655d3d; text-overflow: ellipsis; white-space: nowrap; }
.text-button { padding: 0; border: 0; background: transparent; color: var(--blue); font-weight: 700; cursor: pointer; }
.text-button:hover, .text-button:focus-visible { color: var(--red); }
.local-note { margin: 20px 0 0; color: var(--ink-soft); font-size: .74rem; }

.pronunciation-section { border-top: 1px solid var(--line); }
.sound-group-tabs { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 18px; }
.sound-group-tabs button,
.practice-toggle-row button {
  min-height: 42px; padding: 0 16px; border: 1px solid var(--line); border-radius: 9px; background: transparent; color: var(--ink-soft); font: 700 .8rem var(--sans); cursor: pointer;
}
.sound-group-tabs button[aria-selected="true"],
.practice-toggle-row button[aria-selected="true"],
.practice-toggle-row button[aria-pressed="true"] { border-color: var(--control-bg); background: var(--control-bg); color: var(--control-fg); }
.sound-grid { display: grid; grid-template-columns: repeat(4, 1fr); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.sound-card { position: relative; display: grid; min-height: 135px; place-content: center; border: 0; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); background: transparent; color: var(--ink); text-align: center; cursor: pointer; }
.sound-card:hover,.sound-card:focus-visible { background: var(--paper-light); outline: 2px solid var(--gold); outline-offset: -2px; }
.sound-card.lesson-practiced { box-shadow: inset 0 -4px 0 rgba(215, 75, 56, .45); }
.sound-card strong { font-size: 2.25rem; font-weight: 500; }
.sound-card > span:not(.sound-number) { margin-top: 4px; font: 600 1.3rem var(--serif-sc); }
.sound-card small { margin-top: 5px; color: var(--ink-soft); font-size: .7rem; }
.sound-number { position: absolute; top: 12px; left: 12px; display: grid; width: 25px; height: 25px; place-items: center; border-radius: 7px; background: var(--gold); color: var(--ink); font-size: .68rem; font-weight: 800; }
.sound-notes { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; margin-top: 18px; }
.spelling-rule { border-radius: 14px; background: var(--ink); color: white; padding: 18px 22px; }
.spelling-rule strong { color: #e8cf8b; font-size: 1.5rem; }
.spelling-rule p { margin: 9px 0 0; color: rgba(255,255,255,.72); line-height: 1.6; }

.vocab-section { background: var(--paper-light); width: 100%; max-width: none; padding-inline: max(20px, calc((100vw - 1180px) / 2)); }
.vocab-controls { display: grid; gap: 20px; }
.search-box { display: flex; align-items: center; gap: 12px; min-height: 58px; padding: 0 18px; border: 1px solid var(--line); background: var(--paper-light); border-radius: 10px; }
.search-box:focus-within { border-color: var(--teal); box-shadow: 0 0 0 3px rgba(63,118,84,.12); }
.search-box input { width: 100%; border: 0; outline: 0; background: transparent; color: var(--ink); }
.filter-row { display: flex; flex-wrap: wrap; gap: 8px; }
.filter-chip {
  min-height: 38px; padding: 0 14px; border: 1px solid var(--line); background: transparent; color: var(--ink-soft);
  border-radius: 99px; cursor: pointer; font-size: .78rem; font-weight: 700;
}
.filter-chip.active { background: var(--control-bg); border-color: var(--control-bg); color: var(--control-fg); }
.mastery-filters .filter-chip { display: inline-flex; align-items: center; gap: 7px; }
.mastery-dot { width: 12px; height: 12px; border: 1px solid rgba(25,39,30,.2); border-radius: 50%; }
.mastery-dot.yellow { background: #f3d46b; }
.mastery-dot.orange { background: #f2a65a; }
.mastery-dot.purple { background: #a982d5; }
.vocab-meta { display: flex; justify-content: space-between; align-items: center; margin: 32px 0 18px; }
.vocab-meta p { margin: 0; color: var(--ink-soft); font-size: .82rem; }
.vocab-grid { display: grid; grid-template-columns: repeat(4, 1fr); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.word-card { min-height: 190px; padding: 24px; border: 0; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); background: transparent; color: var(--ink); text-align: left; }
.word-card:hover { background: var(--paper-light); }
.word-card.mastery-known { background: #fff0a8; color: #2d2a1d; }
.word-card.mastery-writing { background: #ffd0a3; color: #382414; }
.word-card.mastery-both { background: #dac1ff; color: #281d36; }
.word-card.mastery-known:hover { background: #f9e381; }
.word-card.mastery-writing:hover { background: #f9bc83; }
.word-card.mastery-both:hover { background: #c9a6f6; }
.word-card.mastery-known .word-pinyin,.word-card.mastery-writing .word-pinyin,.word-card.mastery-both .word-pinyin { color: currentColor; opacity: .72; }
.word-card.mastery-known .word-meaning,.word-card.mastery-writing .word-meaning,.word-card.mastery-both .word-meaning { color: currentColor; opacity: .72; }
.mastery-label { display: inline-block; margin-top: 10px; color: currentColor; font-size: .65rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.mastery-label.state-new { border: 1px solid var(--learning-new); border-radius: 999px; background: var(--learning-new-bg); padding: 3px 8px; color: var(--learning-new); }
.word-hanzi { margin: 0; font-family: var(--serif-sc); font-size: 2.35rem; line-height: 1.2; }
.word-pinyin { margin: 8px 0 0; color: var(--teal); font-size: .84rem; transition: opacity .2s ease; }
.vocab-grid.hide-pinyin .word-card .word-pinyin { opacity: 0; }
.word-meaning { margin: 18px 0 0; color: var(--ink-soft); font-size: .86rem; line-height: 1.4; }
.word-category { display: block; margin-top: 16px; color: var(--red); font-size: .66rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase; }
.empty-state { padding: 50px; text-align: center; color: var(--ink-soft); }

.writing-section { min-height: 560px; }
.writing-heading { display: flex; align-items: center; justify-content: space-between; gap: 18px; }
.writing-heading strong { display: grid; min-width: 62px; height: 62px; place-items: center; border-radius: 50%; background: var(--control-bg); color: var(--control-fg); font-size: 1.2rem; }
.writing-word-form { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 10px; max-width: 680px; }
.writing-word-form input { width: 100%; min-height: 50px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper-light); color: var(--ink); padding: 0 16px; font: 600 1.35rem var(--serif-sc); outline: none; }
.writing-word-form input:focus { border-color: var(--teal); box-shadow: 0 0 0 3px rgba(63,118,84,.12); }
.writing-save-status { margin: 12px 0 24px; color: var(--ink-soft); font-size: .74rem; }
.writing-word-list { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 9px; margin: 0; padding: 0; list-style: none; }
.writing-word-list li { display: flex; min-height: 70px; align-items: center; justify-content: space-between; gap: 8px; border: 1px solid var(--line); border-radius: 10px; background: var(--paper-light); padding: 12px 10px 12px 16px; }
.writing-word-list span { font: 600 1.55rem var(--serif-sc); }
.writing-word-list button { width: 30px; height: 30px; border: 0; border-radius: 50%; background: transparent; color: var(--ink-soft); cursor: pointer; font-size: 1.1rem; }
.writing-word-list button:hover,.writing-word-list button:focus-visible { background: var(--red); color: white; }

.practice-section { min-height: 640px; }
.practice-controls { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; margin-bottom: 18px; }
.practice-toggle-row { display: flex; flex-wrap: wrap; gap: 8px; }
.practice-topic-tabs { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 22px; }
.practice-list { display: grid; gap: 12px; }
.practice-card { padding: 24px; border: 1px solid var(--line); border-radius: 14px; background: var(--paper-light); }
.practice-card-top { display: flex; align-items: center; justify-content: space-between; gap: 12px; color: var(--ink-soft); font-size: .72rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.practice-speak { display: grid; width: 34px; height: 34px; place-items: center; border: 1px solid var(--line); border-radius: 50%; background: transparent; color: var(--ink); cursor: pointer; }
.practice-prompt { margin: 22px 0; }
.practice-chinese { font: 600 clamp(1.45rem, 3vw, 2rem)/1.6 var(--serif-sc); }
.practice-pinyin { color: var(--teal); font-size: 1rem; }
.practice-reveal { min-height: 42px; padding: 0 18px; border: 1px solid var(--reveal-bg); border-radius: 8px; background: var(--reveal-bg); color: var(--reveal-fg); font-weight: 800; cursor: pointer; }
.practice-reveal:hover, .practice-reveal:focus-visible { border-color: var(--reveal-hover); background: var(--reveal-hover); color: var(--reveal-fg); outline: 3px solid color-mix(in srgb, var(--reveal-hover) 28%, transparent); outline-offset: 2px; }
.practice-answer { margin-top: 16px; padding: 16px; border-left: 4px solid var(--gold); background: var(--paper); }
.practice-answer strong { color: var(--red); font-size: .7rem; letter-spacing: .08em; text-transform: uppercase; }
.practice-answer p { margin: 6px 0 0; }
.practice-new-words { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 14px; }
.practice-new-words span { padding: 5px 8px; border: 1px solid var(--learning-new); border-radius: 6px; background: var(--learning-new-bg); color: var(--learning-new); font-size: .7rem; }
.practice-new-words span::before { content: "NEW · "; font-weight: 900; }
.lesson-grammar-block { margin: 18px 0 14px; }
.lesson-grammar-block .grammar-sentence { gap: 10px 4px; padding: 4px 0 8px; }
.lesson-grammar-block .grammar-layer-hanzi .grammar-unit,
.lesson-grammar-block .grammar-layer-pinyin .grammar-unit { min-width: 46px; grid-template-rows: auto 36px; }
.lesson-grammar-block .grammar-layer-both .grammar-unit { min-width: 46px; grid-template-rows: auto auto 36px; }
.lesson-grammar-block .grammar-hanzi { font-size: clamp(1.5rem, 3vw, 2.15rem); line-height: 1.3; }
.lesson-grammar-block .grammar-pinyin { color: currentColor; }
.lesson-grammar-block .grammar-pinyin-primary { min-height: 0; font-size: clamp(.95rem, 2vw, 1.25rem); line-height: 1.45; opacity: 1; }
.lesson-grammar-block .grammar-layer-pinyin .grammar-punctuation { font: 700 clamp(.95rem, 2vw, 1.25rem)/1.45 var(--sans); }
.lesson-grammar-block .grammar-bracket { min-width: 46px; margin-top: 5px; font-size: .54rem; }
.lesson-grammar-block .grammar-punctuation { font-size: clamp(1.5rem, 3vw, 2.15rem); line-height: 1.3; }
.lesson-grammar-legend { margin-top: 4px; }
.practice-grammar-reading .grammar-sentence { gap-block: 8px; line-height: 1.5; }
.practice-grammar-reading .grammar-hanzi,
.practice-grammar-reading .grammar-punctuation { font-size: clamp(1.3rem, 2.5vw, 1.8rem); }
.practice-grammar-reading .grammar-pinyin-primary { font-size: clamp(.82rem, 1.7vw, 1.05rem); }
.practice-grammar-reading .grammar-layer-pinyin .grammar-punctuation { font-size: clamp(.82rem, 1.7vw, 1.05rem); line-height: 1.45; }
.practice-answer-grammar { margin: 8px 0 0; }
.practice-answer-grammar .grammar-sentence { padding-top: 0; }
.practice-answer-grammar .grammar-legend { margin-top: 2px; }
.lesson-feature-grammar { margin-top: 20px; }
.lesson-feature-grammar .grammar-sentence { padding-bottom: 2px; }
.lesson-feature-grammar .grammar-hanzi,
.lesson-feature-grammar .grammar-punctuation { font-size: clamp(1.45rem, 2.6vw, 2.1rem); }

.grammar-reading-section { min-height: 640px; padding-block: 72px; }
.reading-heading { display: flex; align-items: center; justify-content: space-between; gap: 20px; margin-bottom: 22px; }
.reading-heading h2 { margin: 0; font: 700 clamp(2rem, 5vw, 3.2rem)/1 var(--serif-sc); }
.reading-heading > strong { border: 1px solid var(--line); border-radius: 999px; background: var(--paper-light); padding: 8px 14px; font-size: .76rem; }
.reading-toolbar { display: flex; align-items: end; gap: 10px; margin-bottom: 16px; }
.reading-toolbar label { display: grid; gap: 5px; min-width: 190px; color: var(--ink-soft); font-size: .72rem; font-weight: 800; }
.reading-toolbar select { min-height: 50px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper-light); color: var(--ink); padding: 0 38px 0 14px; font: 750 .86rem var(--sans); }
.grammar-reading-card { min-height: 390px; border: 1px solid var(--line); border-radius: 20px; background: var(--paper-light); padding: clamp(22px, 4vw, 46px); box-shadow: var(--shadow); }
.grammar-reading-card.is-empty { display: grid; place-content: center; text-align: center; }
.reading-card-top { display: flex; align-items: center; justify-content: space-between; gap: 16px; color: var(--ink-soft); font-size: .73rem; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; }
.reading-speak { display: grid; width: 44px; height: 44px; place-items: center; border: 1px solid var(--line); border-radius: 50%; background: var(--paper); color: var(--ink); cursor: pointer; }
.reading-speak.speakable-mandarin::after { content: none; }
.reading-focus { display: flex; align-items: baseline; flex-wrap: wrap; gap: 10px; margin: 14px 0 28px; }
.reading-focus strong { font: 700 1.4rem var(--serif-sc); }
.reading-focus span { color: var(--ink-soft); font-size: .78rem; }
.grammar-sentence { display: flex; align-items: flex-start; flex-wrap: wrap; gap: 14px 5px; padding: 10px 0 20px; }
.grammar-unit { display: grid; min-width: 50px; grid-template-rows: auto auto 42px; justify-items: center; color: var(--grammar-particle); }
.grammar-hanzi { color: currentColor; font: 700 clamp(1.9rem, 4.2vw, 3.5rem)/1.15 var(--serif-sc); white-space: nowrap; }
.grammar-pinyin { min-height: 23px; color: currentColor; font-size: clamp(.65rem, 1.3vw, .82rem); font-weight: 700; opacity: .82; white-space: nowrap; }
.grammar-bracket { position: relative; display: grid; width: 100%; min-width: 52px; place-items: start center; margin-top: 8px; border-top: 2px solid currentColor; color: currentColor; font-size: .6rem; font-style: normal; font-weight: 900; letter-spacing: .025em; line-height: 1.15; text-align: center; }
.grammar-bracket::before,.grammar-bracket::after { content: ""; position: absolute; top: -2px; width: 2px; height: 7px; background: currentColor; }
.grammar-bracket::before { left: 0; }
.grammar-bracket::after { right: 0; }
.grammar-bracket span { padding-top: 7px; }
.grammar-punctuation { align-self: start; margin-top: -2px; color: var(--ink); font: 700 clamp(1.9rem, 4.2vw, 3.5rem)/1.15 var(--serif-sc); }
.grammar-sentence .speakable-mandarin::after { content: none; }
.reading-english { margin: 22px 0 0; border-top: 1px solid var(--line); padding-top: 20px; font-size: 1rem; font-weight: 700; }
.grammar-legend { display: flex; flex-wrap: wrap; gap: 7px 14px; margin-top: 18px; }
.grammar-legend > span { display: inline-flex; align-items: center; gap: 6px; color: var(--ink-soft); font-size: .68rem; font-weight: 800; }
.grammar-legend i { display: block; width: 10px; height: 10px; border-radius: 3px; background: currentColor; }
.reading-navigation { display: flex; justify-content: center; gap: 10px; margin-top: 16px; }
.reading-navigation .button { min-width: 150px; }
.hearing-section { min-height: 640px; padding-block: 72px; }
.hearing-heading { display: flex; align-items: center; justify-content: space-between; gap: 20px; margin-bottom: 22px; }
.hearing-heading h2 { margin: 0; font: 700 clamp(2rem, 5vw, 3.2rem)/1 var(--serif-sc); }
.hearing-heading > strong { border: 1px solid var(--line); border-radius: 999px; background: var(--paper-light); padding: 8px 14px; font-size: .76rem; }
.hearing-toolbar { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 16px; color: var(--ink-soft); font-size: .76rem; font-weight: 800; }
.hearing-card { display: grid; min-height: 360px; place-items: center; align-content: center; gap: 28px; border: 1px solid var(--line); border-radius: 20px; background: var(--paper-light); padding: clamp(24px, 5vw, 52px); box-shadow: var(--shadow); text-align: center; }
.hearing-play { display: grid; width: 150px; height: 150px; place-content: center; gap: 8px; border: 1px solid var(--control-bg); border-radius: 50%; background: var(--control-bg); color: var(--control-fg); cursor: pointer; box-shadow: 0 18px 40px color-mix(in srgb, var(--control-bg) 30%, transparent); }
.hearing-play:hover,.hearing-play:focus-visible { background: var(--control-hover); outline: 4px solid color-mix(in srgb, var(--control-bg) 25%, transparent); outline-offset: 4px; }
.hearing-play span { font-size: 2rem; transform: translateX(3px); }
.hearing-play strong { font-size: .78rem; letter-spacing: .08em; text-transform: uppercase; }
.hearing-answer { display: grid; justify-items: center; gap: 8px; }
.hearing-answer[hidden] { display: none; }
.hearing-answer > strong { font: 700 clamp(1.8rem, 5vw, 3.4rem)/1.35 var(--serif-sc); }
.hearing-answer > span { color: var(--teal); font-size: clamp(.9rem, 2vw, 1.15rem); font-weight: 750; }
.hearing-answer > p { margin: 8px 0 0; color: var(--ink-soft); font-size: 1rem; font-weight: 700; }
.hearing-actions { display: flex; justify-content: center; gap: 10px; margin-top: 16px; }
.hearing-actions .button { min-width: 150px; }
.talking-section { min-height: 640px; padding-block: 72px; }
.talking-heading { display: flex; align-items: flex-end; justify-content: space-between; gap: 20px; margin-bottom: 22px; }
.talking-heading .eyebrow { margin-bottom: 8px; }
.talking-heading h2 { margin: 0; font: 700 clamp(2rem, 5vw, 3.2rem)/1 var(--serif-sc); }
.talking-heading > strong { border: 1px solid var(--line); border-radius: 999px; background: var(--paper-light); padding: 8px 14px; font-size: .76rem; }
.talking-console { overflow: hidden; border: 1px solid var(--line); border-radius: 22px; background: var(--paper-light); box-shadow: var(--shadow); }
.talking-clock { display: grid; grid-template-columns: 1fr 1fr; gap: 1px; background: var(--line); }
.talking-clock > div { display: grid; gap: 2px; background: var(--paper-light); padding: 18px clamp(18px, 4vw, 34px); }
.talking-clock span { color: var(--ink-soft); font-size: .68rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.talking-clock strong { font-size: clamp(1.4rem, 3vw, 2rem); font-variant-numeric: tabular-nums; }
.talking-progress-track { height: 8px; background: color-mix(in srgb, var(--control-bg) 12%, transparent); }
.talking-progress-track > span { display: block; width: 0; height: 100%; background: linear-gradient(90deg, var(--control-bg), var(--gold)); transition: width .25s linear; }
.talking-stage { position: relative; display: grid; min-height: 350px; align-content: center; padding: clamp(24px, 5vw, 54px); }
.talking-stage-top { position: absolute; align-self: start; display: flex; justify-content: space-between; width: calc(100% - clamp(48px, 10vw, 108px)); color: var(--ink-soft); font-size: .72rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.talking-stage-top strong { color: var(--teal); }
.talking-cue { text-align: center; }
.talking-cue > span { color: var(--red); font-size: .76rem; font-weight: 900; letter-spacing: .12em; text-transform: uppercase; }
.talking-cue > p { margin: 12px auto 0; max-width: 620px; font: 650 clamp(1.65rem, 4vw, 3rem)/1.25 var(--serif-sc); }
.talking-reveal { display: grid; justify-items: center; gap: 7px; margin-top: 30px; text-align: center; }
.talking-reveal[hidden] { display: none; }
.talking-reveal strong { font: 700 clamp(1.75rem, 4.5vw, 3.3rem)/1.35 var(--serif-sc); }
.talking-reveal > span { color: var(--teal); font-size: clamp(.9rem, 2vw, 1.1rem); font-weight: 750; }
.talking-reveal p { margin: 8px 0 0; font-size: 1rem; font-weight: 750; }
.talking-reveal small { color: var(--ink-soft); font-size: .72rem; }
.talking-options { display: flex; flex-wrap: wrap; align-items: center; justify-content: center; gap: 10px 16px; border-top: 1px solid var(--line); padding: 16px 20px 0; color: var(--ink-soft); font-size: .76rem; font-weight: 800; }
.talking-option-field { display: flex; align-items: center; gap: 10px; }
.talking-options select { min-height: 42px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper); color: var(--ink); padding: 0 34px 0 12px; font: 750 .82rem var(--sans); }
.talking-lock-option { display: inline-flex; min-height: 42px; align-items: center; gap: 8px; cursor: pointer; }
.talking-lock-option input { width: 20px; height: 20px; margin: 0; accent-color: var(--teal); }
.talking-voice-rate { border: 1px solid var(--line); border-radius: 999px; background: var(--paper); padding: 7px 11px; color: var(--ink); font-variant-numeric: tabular-nums; }
.talking-lock-status { margin: 8px 20px 0; color: var(--ink-soft); font-size: .7rem; font-weight: 700; text-align: center; }
.talking-actions { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; padding: 16px 20px 24px; }
.talking-stop { border-color: var(--learning-incorrect); background: var(--learning-incorrect-bg); color: var(--learning-incorrect); }
.talking-actions .button:disabled { cursor: not-allowed; opacity: .42; transform: none; }
.grammar-unit[data-role="time"],.grammar-legend [data-role="time"] { color: var(--grammar-time); }
.grammar-unit[data-role="subject"],.grammar-legend [data-role="subject"] { color: var(--grammar-subject); }
.grammar-unit[data-role="place"],.grammar-legend [data-role="place"] { color: var(--grammar-place); }
.grammar-unit[data-role="adverb"],.grammar-legend [data-role="adverb"] { color: var(--grammar-adverb); }
.grammar-unit[data-role="modal"],.grammar-legend [data-role="modal"] { color: var(--grammar-modal); }
.grammar-unit[data-role="verb"],.grammar-legend [data-role="verb"] { color: var(--grammar-verb); }
.grammar-unit[data-role="object"],.grammar-legend [data-role="object"] { color: var(--grammar-object); }
.grammar-unit[data-role="complement"],.grammar-legend [data-role="complement"] { color: var(--grammar-complement); }
.grammar-unit[data-role="modifier"],.grammar-legend [data-role="modifier"] { color: var(--grammar-modifier); }
.grammar-unit[data-role="measure"],.grammar-legend [data-role="measure"] { color: var(--grammar-measure); }
.grammar-unit[data-role="connector"],.grammar-legend [data-role="connector"] { color: var(--grammar-connector); }
.grammar-unit[data-role="particle"],.grammar-legend [data-role="particle"] { color: var(--grammar-particle); }
.grammar-unit[data-role="question"],.grammar-legend [data-role="question"] { color: var(--grammar-question); }
.grammar-unit[data-role="greeting"],.grammar-legend [data-role="greeting"] { color: var(--grammar-greeting); }

.speakable-mandarin, [data-speak-mandarin] { cursor: pointer; }
.speakable-mandarin::after, [data-speak-mandarin]::after { content: "🔊"; margin-left: .35em; font-family: system-ui, sans-serif; font-size: .45em; opacity: .42; vertical-align: middle; }
.speakable-mandarin:hover::after, .speakable-mandarin:focus-visible::after, [data-speak-mandarin]:hover::after, [data-speak-mandarin]:focus-visible::after { opacity: 1; }
.speakable-mandarin:focus-visible, [data-speak-mandarin]:focus-visible { outline: 2px solid var(--gold); outline-offset: 4px; }
.closing-section { padding-block: 150px; text-align: center; }
.closing-chinese { margin: 0 0 16px; color: var(--red); font-family: var(--serif-sc); font-size: 1.8rem; }
.closing-section > p:not(.closing-chinese) { color: var(--ink-soft); }
.closing-section .button { margin-top: 20px; }
.site-footer { display: flex; justify-content: space-between; align-items: flex-end; gap: 30px; padding-block: 35px; border-top: 1px solid var(--line); color: var(--ink-soft); font-size: .78rem; }
.site-footer > div { display: flex; gap: 12px; align-items: center; }
.site-footer p { margin: 0; }
.site-footer strong { color: var(--ink); }

:root[data-theme="dark"] .lesson-feature,
:root[data-theme="dark"] .session-panel { background: #24332a; }
:root[data-theme="dark"] .listening-card { background: #3b3425; }
:root[data-theme="dark"] .hero-phrase,
:root[data-theme="dark"] .spelling-rule { background: #0d120f; color: #f2f5f1; }
:root[data-theme="dark"] .button-primary,
:root[data-theme="dark"] .mandarin-section-menu a[aria-current="page"],
:root[data-theme="dark"] .session-list li.active .session-number,
:root[data-theme="dark"] .filter-chip.active,
:root[data-theme="dark"] .sound-group-tabs button[aria-selected="true"],
:root[data-theme="dark"] .practice-toggle-row button[aria-selected="true"],
:root[data-theme="dark"] .practice-toggle-row button[aria-pressed="true"] { border-color: var(--control-bg); background: var(--control-bg); color: var(--control-fg); }
:root[data-theme="dark"] .word-card.mastery-known { background: #5d5124; color: #fff4b9; }
:root[data-theme="dark"] .word-card.mastery-writing { background: #603b1f; color: #ffd8b5; }
:root[data-theme="dark"] .word-card.mastery-both { background: #493663; color: #ead8ff; }
:root[data-theme="dark"] .known-word-chip { background: #5d5124; color: #fff4b9; }
:root[data-theme="dark"] .known-word-chip small { color: #e8d98f; }

@media (max-width: 1000px) {
  .hero { grid-template-columns: 1fr; min-height: auto; }
  .hero-copy { padding-top: 35px; }
  .hero-phrase { max-width: 680px; }
  .study-layout { grid-template-columns: 1fr; }
  .session-panel { display: grid; grid-template-columns: 1fr 1fr; column-gap: 40px; }
  .session-panel .eyebrow, .session-panel h3 { grid-column: 1; }
  .session-list { grid-column: 2; grid-row: 1 / span 4; }
  .known-word-list { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .greeting-grid { grid-template-columns: repeat(3, 1fr); }
  .lesson-feature-grid { grid-template-columns: 1fr; }
  .vocab-grid { grid-template-columns: repeat(3, 1fr); }
  .writing-word-list { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (max-width: 720px) {
  .section-shell { width: min(100% - 28px, 1180px); }
  .mandarin-section-menu { width: min(100% - 28px, 1000px); grid-template-columns: repeat(2, minmax(0, 1fr)); margin-top: 24px; }
  .hero { padding-block: 48px 76px; gap: 64px; }
  .hero h1 { font-size: clamp(3.1rem, 15vw, 5.3rem); }
  .hero-stats { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
  .hero-phrase { padding: 36px 26px; }
  .seal { width: 66px; height: 66px; right: 20px; }
  .lessons-section, .lesson-section, .study-section, .pronunciation-section, .vocab-section, .writing-section, .practice-section, .grammar-reading-section, .hearing-section, .talking-section { padding-block: 64px; }
  .lesson-heading { align-items: stretch; flex-direction: column; }
  .lesson-heading .button { width: 100%; }
  .lesson-list { grid-template-columns: 1fr; }
  .split-heading { grid-template-columns: 1fr; gap: 18px; }
  .section-heading { margin-bottom: 34px; }
  .section-heading h2, .closing-section h2 { font-size: clamp(2.5rem, 13vw, 4rem); }
  .flashcard { min-height: 330px; padding: 24px; }
  .flash-actions { display: grid; grid-template-columns: 1fr 1fr; }
  .flash-actions .button { min-width: 0; padding-inline: 12px; }
  .session-panel { display: block; }
  .known-word-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .greeting-grid { grid-template-columns: repeat(2, 1fr); }
  .greeting-card { min-height: 170px; padding: 18px; }
  .lesson-feature { padding: 24px; }
  .lesson-sound-focus { align-items: flex-start; flex-direction: column; }
  .sound-grid { grid-template-columns: repeat(2, 1fr); }
  .sound-card { min-height: 125px; }
  .sound-notes { grid-template-columns: 1fr; }
  .vocab-section { padding-inline: 14px; }
  .vocab-grid { grid-template-columns: repeat(2, 1fr); }
  .writing-word-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grammar-reading-card { min-height: 360px; padding: 24px 18px; }
  .hearing-card { min-height: 330px; padding: 26px 18px; }
  .hearing-play { width: 132px; height: 132px; }
  .grammar-sentence { gap-inline: 3px; }
  .grammar-unit { min-width: 42px; grid-template-rows: auto auto 39px; }
  .grammar-bracket { min-width: 44px; font-size: .54rem; }
  .talking-heading { align-items: flex-start; flex-direction: column; }
  .talking-stage { min-height: 320px; }
  .talking-stage-top { position: static; width: 100%; margin-bottom: 44px; }
  .talking-actions { display: grid; grid-template-columns: 1fr 1fr; }
  .talking-actions .button { padding-inline: 10px; }
  .word-card { min-height: 170px; padding: 18px; }
  .word-hanzi { font-size: 1.95rem; }
  .closing-section { padding-block: 100px; }
  .site-footer { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 420px) {
  .brand small { display: none; }
  .greeting-grid { grid-template-columns: 1fr; }
  .vocab-grid { grid-template-columns: 1fr; }
  .word-card { min-height: auto; }
  .writing-word-form { grid-template-columns: 1fr; }
  .writing-word-list { grid-template-columns: 1fr; }
  .known-word-list { grid-template-columns: 1fr; }
  .reading-toolbar { align-items: stretch; flex-direction: column; }
  .reading-toolbar label { min-width: 0; }
  .reading-navigation { display: grid; grid-template-columns: 1fr 1fr; }
  .reading-navigation .button { min-width: 0; padding-inline: 10px; }
  .hearing-heading { align-items: flex-start; flex-direction: column; }
  .hearing-actions { display: grid; grid-template-columns: 1fr 1fr; }
  .hearing-actions .button { min-width: 0; padding-inline: 10px; }
}

@media (max-width: 420px) {
  .talking-clock { grid-template-columns: 1fr; }
  .talking-actions { grid-template-columns: 1fr; }
  .talking-options { align-items: stretch; flex-direction: column; }
  .talking-option-field { align-items: stretch; flex-direction: column; }
  .talking-lock-option { justify-content: flex-start; }
  .talking-voice-rate { align-self: flex-start; }
}

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

/* Universal button-border contract: every enabled button renders a visible 1px border. */
button:not(:disabled) {
  border-style: solid !important;
  border-width: 1px !important;
}