:root {
  --bg: #f7f3ec;
  --panel: #fffdf9;
  --panel-2: #f1ebe0;
  --ink: #1f1a17;
  --ink-2: #5d544c;
  --ink-3: #8f857b;
  --line: #e4dccf;
  --accent: #c0392b;
  --accent-ink: #fff;
  --accent-soft: #f8e1dc;
  --jade: #1f7a63;
  --jade-soft: #dcefe8;
  --warn: #b7791f;
  --warn-soft: #fbefd6;
  --t1: #d63a2f;
  --t2: #d98a00;
  --t3: #2e8b3d;
  --t4: #2f64c8;
  --t5: #8a8580;
  --shadow: 0 1px 2px rgba(40, 25, 10, .06), 0 4px 16px rgba(40, 25, 10, .06);
  --radius: 14px;
  --font: 'Inter', 'Noto Sans SC', system-ui, sans-serif;
  --han: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --han-serif: 'Noto Serif SC', 'Songti SC', 'SimSun', serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #161412; --panel: #1f1c19; --panel-2: #29251f; --ink: #f1ebe3; --ink-2: #c3b9ad; --ink-3: #8c8278;
    --line: #37312a; --accent: #e5574a; --accent-soft: #3d201c; --jade: #4cc09d; --jade-soft: #173229;
    --warn: #e0a84a; --warn-soft: #3a2c14;
    --t1: #ff6b5e; --t2: #f4b23c; --t3: #5cc46c; --t4: #6f9cff; --t5: #9d968f;
    --shadow: 0 1px 2px rgba(0,0,0,.3), 0 4px 16px rgba(0,0,0,.25);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #161412; --panel: #1f1c19; --panel-2: #29251f; --ink: #f1ebe3; --ink-2: #c3b9ad; --ink-3: #8c8278;
  --line: #37312a; --accent: #e5574a; --accent-soft: #3d201c; --jade: #4cc09d; --jade-soft: #173229;
  --warn: #e0a84a; --warn-soft: #3a2c14;
  --t1: #ff6b5e; --t2: #f4b23c; --t3: #5cc46c; --t4: #6f9cff; --t5: #9d968f;
  --shadow: 0 1px 2px rgba(0,0,0,.3), 0 4px 16px rgba(0,0,0,.25);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg); color: var(--ink); font: 15px/1.55 var(--font);
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; }
button { font: inherit; color: inherit; }
h1, h2, h3 { line-height: 1.25; margin: 0 0 .4em; }
h1 { font-size: 1.7rem; }
h2 { font-size: 1.25rem; }
h3 { font-size: 1.05rem; }
p { margin: 0 0 .8em; }
.han { font-family: var(--han); }
.muted { color: var(--ink-2); }
.small { font-size: .85rem; }
.hidden { display: none !important; }

/* ---------- Layout ---------- */
.app { display: grid; grid-template-columns: 232px minmax(0, 1fr); min-height: 100vh; }
.side {
  position: sticky; top: 0; height: 100vh; padding: 20px 14px; border-right: 1px solid var(--line);
  background: var(--panel); display: flex; flex-direction: column; gap: 4px;
}
.brand { display: flex; align-items: center; gap: 10px; padding: 4px 8px 18px; text-decoration: none; }
.brand .seal {
  width: 38px; height: 38px; border-radius: 9px; background: var(--accent); color: var(--accent-ink);
  display: grid; place-items: center; font: 700 22px var(--han-serif);
}
.brand b { display: block; font-size: 1rem; }
.brand small { color: var(--ink-3); font-size: .75rem; }
.nav a {
  display: flex; align-items: center; gap: 10px; padding: 9px 10px; border-radius: 10px; text-decoration: none;
  color: var(--ink-2); font-weight: 500;
}
.nav a:hover { background: var(--panel-2); color: var(--ink); }
.nav a.on { background: var(--accent-soft); color: var(--accent); }
.nav .ico { width: 22px; text-align: center; font-family: var(--han); font-weight: 700; }
.nav .badge { margin-left: auto; }
.side .foot { margin-top: auto; font-size: .75rem; color: var(--ink-3); padding: 8px; }

main { padding: 28px clamp(16px, 4vw, 48px) 80px; max-width: 1100px; width: 100%; }

@media (max-width: 820px) {
  .app { grid-template-columns: minmax(0, 1fr); }
  .side {
    position: fixed; bottom: 0; top: auto; left: 0; right: 0; height: auto; z-index: 20; flex-direction: row;
    padding: 6px; border-right: 0; border-top: 1px solid var(--line); justify-content: space-around;
  }
  .brand, .side .foot { display: none; }
  .nav { display: contents; }
  .nav a { flex-direction: column; gap: 0; font-size: .68rem; padding: 6px 4px; min-width: 0; }
  .nav .ico { font-size: 1.1rem; }
  .nav .badge { position: absolute; margin: -4px 0 0 18px; }
  .nav a { position: relative; }
  main { padding: 18px 16px 96px; }
}

/* ---------- Components ---------- */
.card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow); }
.grid { display: grid; gap: 14px; }
.g2 { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }
.g3 { grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); }
.g4 { grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); }
.row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.spacer { flex: 1; }
.stack > * + * { margin-top: 14px; }
.section { margin-top: 28px; }

.btn {
  display: inline-flex; align-items: center; gap: 6px; padding: 8px 14px; border-radius: 10px; cursor: pointer;
  border: 1px solid var(--line); background: var(--panel); font-weight: 600; text-decoration: none; white-space: nowrap;
}
.btn:hover { border-color: var(--ink-3); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.primary:hover { filter: brightness(1.07); }
.btn.jade { background: var(--jade); border-color: var(--jade); color: #fff; }
.btn.ghost { background: transparent; border-color: transparent; }
.btn.ghost:hover { background: var(--panel-2); }
.btn.sm { padding: 5px 10px; font-size: .85rem; border-radius: 8px; }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.icon-btn {
  width: 34px; height: 34px; border-radius: 50%; border: 1px solid var(--line); background: var(--panel);
  display: inline-grid; place-items: center; cursor: pointer; font-size: 14px; flex: none;
}
.icon-btn:hover { border-color: var(--accent); color: var(--accent); }
.icon-btn.rec { background: var(--accent); color: #fff; border-color: var(--accent); animation: pulse 1.2s infinite; }
@keyframes pulse { 50% { box-shadow: 0 0 0 7px var(--accent-soft); } }

.badge { display: inline-block; min-width: 20px; padding: 1px 7px; border-radius: 99px; background: var(--accent); color: #fff; font-size: .72rem; font-weight: 700; text-align: center; }
.pill { display: inline-block; padding: 2px 10px; border-radius: 99px; background: var(--panel-2); color: var(--ink-2); font-size: .78rem; font-weight: 600; }
.pill.jade { background: var(--jade-soft); color: var(--jade); }
.pill.red { background: var(--accent-soft); color: var(--accent); }
.pill.warn { background: var(--warn-soft); color: var(--warn); }

.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--line); margin: 18px 0 20px; overflow-x: auto; scrollbar-width: none; }
.tabs a {
  padding: 10px 14px; text-decoration: none; color: var(--ink-2); font-weight: 600; border-bottom: 2px solid transparent;
  white-space: nowrap; margin-bottom: -1px;
}
.tabs a.on { color: var(--accent); border-bottom-color: var(--accent); }
.tabs a .tick { color: var(--jade); margin-left: 4px; }

.bar { height: 8px; background: var(--panel-2); border-radius: 99px; overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--jade); border-radius: 99px; transition: width .3s; }

.notice { padding: 12px 14px; border-radius: 12px; background: var(--warn-soft); color: var(--ink); border: 1px solid transparent; font-size: .9rem; }
.notice.info { background: var(--jade-soft); }

.toggle { display: inline-flex; align-items: center; gap: 6px; cursor: pointer; font-size: .85rem; color: var(--ink-2); user-select: none; }
.toggle input { accent-color: var(--accent); }

/* tone colours */
.t1 { color: var(--t1); } .t2 { color: var(--t2); } .t3 { color: var(--t3); } .t4 { color: var(--t4); } .t5 { color: var(--t5); }
.nocolor .t1, .nocolor .t2, .nocolor .t3, .nocolor .t4, .nocolor .t5 { color: inherit; }

/* ---------- Hero / home ---------- */
.hero { display: grid; grid-template-columns: 1.4fr 1fr; gap: 16px; }
@media (max-width: 820px) { .hero { grid-template-columns: 1fr; } }
.hero .welcome { background: linear-gradient(135deg, var(--accent), #8e2a20); color: #fff; border: 0; position: relative; overflow: hidden; }
.hero .welcome .big { position: absolute; right: -10px; bottom: -40px; font: 700 170px/1 var(--han-serif); opacity: .12; }
.hero .welcome p { opacity: .9; max-width: 44ch; }
.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.stat { text-align: center; padding: 14px 8px; }
.stat b { display: block; font-size: 1.6rem; }
.stat span { font-size: .78rem; color: var(--ink-2); }

.level-card { display: flex; flex-direction: column; gap: 8px; text-decoration: none; }
.level-card.locked { opacity: .55; }
.level-card .lv { font: 700 1.4rem var(--font); }

/* ---------- Lessons ---------- */
.lesson-item { display: grid; grid-template-columns: 46px 1fr auto; gap: 14px; align-items: center; text-decoration: none; }
.lesson-item .num {
  width: 46px; height: 46px; border-radius: 12px; background: var(--panel-2); display: grid; place-items: center;
  font-weight: 700; font-size: 1.1rem;
}
.lesson-item.done .num { background: var(--jade); color: #fff; }
.lesson-item .zh { font: 600 1.15rem var(--han); }
.lesson-item:hover { border-color: var(--ink-3); }

.lesson-head { display: flex; gap: 18px; align-items: flex-start; flex-wrap: wrap; }
.lesson-head .zh { font: 700 2rem var(--han-serif); margin: 0; }
.crumbs { font-size: .85rem; color: var(--ink-3); margin-bottom: 8px; }
.crumbs a { text-decoration: none; color: var(--ink-2); }

/* word card */
.word { display: grid; grid-template-columns: auto 1fr auto; gap: 12px; align-items: center; padding: 12px 14px; }
.word .hz { font: 500 1.9rem/1.1 var(--han); cursor: pointer; }
.word .py { font-weight: 600; }
.word .en { color: var(--ink-2); font-size: .9rem; }
.word .emo { font-size: 1.4rem; }
.word .actions { display: flex; gap: 6px; }

/* flashcard */
.flash {
  min-height: 300px; display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center;
  gap: 10px; cursor: pointer; user-select: none; padding: 28px;
}
.flash .hz { font: 500 4.4rem/1.1 var(--han); }
.flash .py { font-size: 1.4rem; font-weight: 600; }
.flash .en { font-size: 1.1rem; color: var(--ink-2); }
.flash .hint { font-size: .8rem; color: var(--ink-3); }
.grades { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; margin-top: 14px; }
.grades .btn { justify-content: center; flex-direction: column; gap: 0; padding: 10px 6px; }
.grades .btn small { font-weight: 400; color: var(--ink-3); font-size: .72rem; }
.grades .g0 { border-color: var(--accent); color: var(--accent); }
.grades .g3 { border-color: var(--jade); color: var(--jade); }

/* sentence with ruby-style pinyin */
.sent { display: flex; flex-wrap: wrap; align-items: flex-end; gap: 2px 4px; }
.sent .grp { display: inline-flex; align-items: flex-end; gap: 0 2px; }
.tok { display: inline-flex; flex-direction: column; align-items: center; border-radius: 6px; padding: 0 2px; }
.tok .p { font-size: .72rem; color: var(--ink-3); min-height: 1.1em; white-space: nowrap; }
.tok .h { font: 400 1.35rem/1.35 var(--han); }
.tok.w { cursor: pointer; }
.tok.w:hover { background: var(--accent-soft); }
.tok.punct .h { color: var(--ink-3); }
.tok.hit .h { color: var(--jade); }
.tok.miss .h { color: var(--accent); text-decoration: underline wavy; text-underline-offset: 5px; }
.no-py .tok .p { display: none; }
.no-en .line .en { display: none; }
.hide-text .line .sent, .hide-text .line .en { filter: blur(7px); }
.hide-text .line:hover .sent, .hide-text .line:hover .en { filter: none; }

.scene { margin-bottom: 18px; }
.scene h3 { font-size: .8rem; text-transform: uppercase; letter-spacing: .06em; color: var(--ink-3); display: flex; align-items: center; gap: 8px; }
.line { display: grid; grid-template-columns: 56px 1fr auto; gap: 10px; align-items: center; padding: 8px 0; border-top: 1px dashed var(--line); }
.line:first-of-type { border-top: 0; }
.line .who { font: 600 .82rem var(--han); color: var(--ink-3); text-align: right; }
.line .en { font-size: .88rem; color: var(--ink-2); margin-top: 2px; }
.line.playing { background: var(--accent-soft); border-radius: 10px; }
.line .acts { display: flex; gap: 6px; }

/* grammar */
.gram h3 { display: flex; gap: 10px; align-items: baseline; }
.gram h3 .n { color: var(--accent); font-weight: 800; }
.gram .body { color: var(--ink-2); }
.gram .body b { color: var(--ink); font-family: var(--han), var(--font); }
.ex { display: grid; grid-template-columns: 1fr auto; gap: 4px 10px; align-items: center; padding: 8px 12px; background: var(--panel-2); border-radius: 10px; margin-top: 8px; }
.ex .en { grid-column: 1; font-size: .85rem; color: var(--ink-2); }
.ex .icon-btn { grid-row: 1 / span 2; grid-column: 2; }

/* popover */
.pop {
  position: fixed; z-index: 50; background: var(--panel); border: 1px solid var(--line); border-radius: 14px; box-shadow: 0 10px 40px rgba(0,0,0,.18);
  padding: 14px; width: 250px;
}
.pop .hz { font: 500 2.4rem/1.1 var(--han); }
.pop .py { font-weight: 700; font-size: 1.05rem; }
.pop .en { color: var(--ink-2); margin: 2px 0 10px; }
.pop .writer { width: 110px; height: 110px; margin: 6px auto; }

/* writing */
.char-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(62px, 1fr)); gap: 8px; }
.char-cell {
  aspect-ratio: 1; display: grid; place-items: center; font: 400 1.9rem var(--han); background: var(--panel); border: 1px solid var(--line);
  border-radius: 12px; cursor: pointer; position: relative;
}
.char-cell.req::after { content: ''; position: absolute; top: 6px; right: 6px; width: 7px; height: 7px; border-radius: 50%; background: var(--accent); }
.char-cell.done { border-color: var(--jade); background: var(--jade-soft); }
.char-cell.on { outline: 2px solid var(--accent); outline-offset: 1px; }
.writer-wrap { display: grid; grid-template-columns: auto 1fr; gap: 18px; align-items: start; }
@media (max-width: 640px) { .writer-wrap { grid-template-columns: 1fr; justify-items: center; } }
.writer-box {
  width: 260px; height: 260px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); position: relative;
  background-image:
    linear-gradient(to right, transparent calc(50% - .5px), var(--line) calc(50% - .5px), var(--line) calc(50% + .5px), transparent calc(50% + .5px)),
    linear-gradient(to bottom, transparent calc(50% - .5px), var(--line) calc(50% - .5px), var(--line) calc(50% + .5px), transparent calc(50% + .5px)),
    linear-gradient(45deg, transparent calc(50% - .5px), var(--panel-2) calc(50% - .5px), var(--panel-2) calc(50% + .5px), transparent calc(50% + .5px)),
    linear-gradient(-45deg, transparent calc(50% - .5px), var(--panel-2) calc(50% - .5px), var(--panel-2) calc(50% + .5px), transparent calc(50% + .5px));
}
.writer-box svg { display: block; }
.stroke-table td, .stroke-table th { padding: 7px 10px; border-bottom: 1px solid var(--line); text-align: left; }
.stroke-table { border-collapse: collapse; width: 100%; font-size: .92rem; }
.stroke-table .sg { font: 1.5rem var(--han); }

/* quiz */
.quiz { max-width: 680px; margin: 0 auto; }
.quiz .q { font-size: 1.05rem; margin-bottom: 14px; }
.quiz .prompt { text-align: center; padding: 22px 10px; }
.quiz .prompt .hz { font: 500 3.6rem/1.15 var(--han); }
.quiz .prompt .emo { font-size: 4rem; }
.opts { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
@media (max-width: 520px) { .opts { grid-template-columns: 1fr; } }
.opt {
  padding: 14px; border-radius: 12px; border: 1.5px solid var(--line); background: var(--panel); cursor: pointer; text-align: left;
  font-size: 1rem; display: flex; align-items: center; gap: 10px; min-height: 56px;
}
.opt .hz { font: 500 1.5rem var(--han); }
.opt .emo { font-size: 2rem; }
.opt:hover:not(:disabled) { border-color: var(--ink-3); }
.opt.right { border-color: var(--jade); background: var(--jade-soft); }
.opt.wrong { border-color: var(--accent); background: var(--accent-soft); }
.opt:disabled { cursor: default; }
.opts.pics .opt { justify-content: center; font-size: 2.6rem; min-height: 96px; }
.feedback { margin-top: 14px; padding: 12px 14px; border-radius: 12px; }
.feedback.ok { background: var(--jade-soft); }
.feedback.no { background: var(--accent-soft); }
.progress-top { display: flex; align-items: center; gap: 12px; margin-bottom: 18px; }
.progress-top .bar { flex: 1; }

.builder .slot, .builder .bank { min-height: 58px; padding: 8px; border-radius: 12px; display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.builder .slot { border: 1.5px dashed var(--ink-3); }
.builder .bank { background: var(--panel-2); margin-top: 10px; }
.chip { padding: 6px 12px; border-radius: 10px; background: var(--panel); border: 1px solid var(--line); cursor: pointer; font: 500 1.3rem var(--han); box-shadow: var(--shadow); }
.chip:hover { border-color: var(--accent); }

.result { text-align: center; padding: 30px 18px; }
.result .score { font-size: 3.4rem; font-weight: 800; }

/* speaking */
.speak-row { display: grid; grid-template-columns: 1fr auto; gap: 10px; align-items: center; padding: 12px 0; border-top: 1px solid var(--line); }
.speak-row:first-child { border-top: 0; }
.speak-row .heard { font-size: .82rem; color: var(--ink-3); margin-top: 4px; }
.score-badge { font-weight: 800; font-size: .85rem; padding: 2px 8px; border-radius: 8px; }
.score-badge.good { background: var(--jade-soft); color: var(--jade); }
.score-badge.mid { background: var(--warn-soft); color: var(--warn); }
.score-badge.bad { background: var(--accent-soft); color: var(--accent); }

/* pinyin page */
.tone-card { text-align: center; }
.tone-card svg { width: 100%; height: 70px; }
.tone-card .mk { font-size: 2rem; font-weight: 700; }
.py-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(118px, 1fr)); gap: 8px; }
.py-cell { padding: 10px; border-radius: 12px; background: var(--panel); border: 1px solid var(--line); cursor: pointer; text-align: left; }
.py-cell:hover { border-color: var(--accent); }
.py-cell b { font-size: 1.25rem; display: block; }
.py-cell .ex { all: unset; font-size: .8rem; color: var(--ink-2); }
.py-cell .tip { font-size: .72rem; color: var(--ink-3); display: block; line-height: 1.3; margin-top: 3px; }
.quartet { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; }
.quartet button { padding: 10px 4px; border-radius: 12px; background: var(--panel); border: 1px solid var(--line); cursor: pointer; }
.quartet button .hz { font: 1.6rem var(--han); display: block; }

/* settings */
.field { display: grid; gap: 6px; margin-bottom: 16px; }
.field label { font-weight: 600; }
select, input[type="range"], textarea { font: inherit; }
select { padding: 8px 10px; border-radius: 10px; border: 1px solid var(--line); background: var(--panel); color: var(--ink); max-width: 100%; }
input[type="range"] { accent-color: var(--accent); width: 100%; max-width: 320px; }

.empty { text-align: center; padding: 40px 18px; color: var(--ink-2); }
.empty .big { font-size: 3rem; }

.toast {
  position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%); background: var(--ink); color: var(--bg);
  padding: 10px 18px; border-radius: 12px; z-index: 60; font-weight: 600; box-shadow: var(--shadow);
}
@media (max-width: 820px) { .toast { bottom: 84px; } }