:root{
  --bg:#ffffff;
  --header:#ffffff;
  --wash:#f6f8fb;
  --soft:#e8f1ff;
  --blue:#4f7df3;
  --card:#ffffff;
  --card-hover:#e8f1ff;
  --text:#0f172a;
  --muted:#64748b;
  --tile:#f8e9cd;
  --tile-hover:#f3ddb4;
  --vowel:#e5f1ff;
  --vowel-hover:#d2e6ff;
  --consonant:#f0e9ff;
  --consonant-hover:#e4d8ff;
  --symbol:#243247;
  --line:rgba(15,23,42,.08);
  --surface:#ffffff;
  --shadow:0 10px 28px rgba(15,23,42,.05);
  --shadow-soft:0 1px 2px rgba(15,23,42,.04),0 8px 18px rgba(15,23,42,.05);
  --radius:18px;
  --move:220ms ease;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:120px}
body{
  margin:0;
  color:var(--text);
  font:16px/1.6 system-ui,-apple-system,"Noto Sans TC","Microsoft JhengHei",sans-serif;
  background:
    linear-gradient(180deg,#eef4ff 0%,var(--bg) 320px);
  background-color:var(--bg);
  overflow-x:hidden;
}
button,a{font:inherit}
button{cursor:pointer}
a{color:var(--blue);text-decoration:none}
:focus-visible{outline:2px solid var(--blue);outline-offset:3px}
.srOnly{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}

.siteHeader{
  position:sticky;top:0;z-index:20;
  background:var(--header);
  border-bottom:1px solid var(--line);
  box-shadow:0 1px 0 rgba(255,255,255,.8);
}
.headerInner{
  max-width:1120px;margin:auto;
  padding:14px 24px;
  display:flex;align-items:center;justify-content:space-between;gap:18px;
  min-width:0;
}
.brand{color:var(--text);font-weight:600;font-size:1.05rem;letter-spacing:.02em;display:flex;align-items:center;gap:11px;min-height:44px}
.brandLogo{display:block;width:34px;height:34px;flex:none}
.topNav{display:flex;align-items:center;gap:6px;min-width:0}
.navLink{
  color:var(--muted);
  min-height:40px;
  padding:8px 14px;
  border-radius:999px;
  font-weight:600;
  white-space:nowrap;
  transition:background var(--move),color var(--move);
}
.navLink:hover{background:var(--wash);color:var(--text)}
.navLink:active{transform:scale(.98)}
.navLink[aria-current="page"]{background:var(--soft);color:var(--blue)}

main{max-width:1120px;margin:auto;padding:32px 24px 72px;min-height:calc(100vh - 180px)}
.siteFooter{
  max-width:1120px;margin:auto;
  padding:18px 24px 32px;
  border-top:1px solid var(--line);
  color:var(--muted);font-size:.88rem;
}

.eyebrow{margin:0 0 8px;color:var(--blue);font-size:.78rem;font-weight:600;letter-spacing:.08em}
.pageIntro{margin:0 0 28px;max-width:40rem}
.pageIntro h1,.practiceTop h1{margin:0 0 8px;font-size:clamp(1.8rem,3vw,2.6rem);line-height:1.2;font-weight:600;letter-spacing:.04em}
.pageIntro p{margin:0;color:var(--muted)}
.muted{color:var(--muted)}
.count{color:var(--muted);font-size:.92rem;font-weight:600;font-variant-numeric:tabular-nums}

.section,.card{
  background:var(--surface);
  border:1px solid var(--line);
  border-radius:22px;
  box-shadow:var(--shadow);
}
.section{padding:24px;margin-bottom:20px;background:var(--wash)}
.sectionHead,.phraseSection .sectionHead,.wordSection .sectionHead{
  display:flex;align-items:baseline;justify-content:space-between;gap:12px;margin-bottom:14px;
}
.sectionHead h2,.phraseSection h2,.wordSection h2,.positionSection h2,.drillContext h2{
  margin:0;font-size:1.15rem;font-weight:600;letter-spacing:.03em;
}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(112px,1fr));gap:12px}
.tile{
  min-height:96px;
  display:grid;place-items:center;
  border-radius:16px;
  background:var(--tile);
  color:var(--text);
  box-shadow:var(--shadow-soft);
  transition:transform var(--move),box-shadow var(--move),background var(--move);
}
.tile:hover{transform:translateY(-3px);background:var(--tile-hover);box-shadow:0 12px 22px rgba(15,23,42,.08)}
.tile:active{transform:translateY(1px)}
.vowelSection .tile{background:var(--vowel);color:var(--symbol)}
.vowelSection .tile:hover{background:var(--vowel-hover)}
.consonantSection .tile{background:var(--consonant);color:var(--symbol)}
.consonantSection .tile:hover{background:var(--consonant-hover)}
.tileSymbol{font-family:"DejaVu Sans",Arial,sans-serif;font-size:clamp(1.9rem,2.5vw,2.6rem);font-weight:700;line-height:1;color:var(--symbol)}

.crumbBar{max-width:1120px;margin:0 auto;padding:10px 24px 0;color:var(--muted);font-size:.8rem;line-height:1.4}
.crumbBar[hidden]{display:none}
.crumbBar ol{display:flex;flex-wrap:wrap;align-items:center;gap:6px;margin:0;padding:0;list-style:none}
.crumbBar li:not(:last-child)::after{content:"/";margin-left:6px;color:#94a3b8}
.crumbBar a{color:var(--muted)}
.crumbBar a:hover{color:var(--text)}
.crumbBar [aria-current="page"]{color:var(--text)}
.crumb{display:flex;flex-wrap:wrap;align-items:center;gap:8px;margin-bottom:18px;color:var(--muted);font-size:.92rem}
.crumb a{color:var(--muted);padding:2px 0}
.crumb a:hover{color:var(--blue)}

.learnHead,.practiceTop{display:flex;align-items:center;justify-content:space-between;gap:20px;margin-bottom:16px}
.learnExample{margin:8px 0 0;color:var(--muted)}
.learnExample span{color:var(--text);font-weight:600}
.practiceSymbol{font-family:"DejaVu Sans",Arial,sans-serif;font-weight:700}

.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  min-height:44px;padding:0 16px;
  border-radius:12px;border:1px solid transparent;
  font-weight:600;
  transition:background var(--move),border-color var(--move),transform var(--move),box-shadow var(--move),color var(--move);
}
.btn.primary{background:var(--blue);color:#fff}
.btn.primary:hover{background:#3d6ae0;transform:translateY(-1px);box-shadow:0 8px 18px rgba(79,125,243,.22)}
.btn.secondary{background:#fff;border-color:var(--line);color:var(--text);box-shadow:var(--shadow-soft)}
.btn.secondary:hover{background:var(--wash);transform:translateY(-1px)}
.btn:active{transform:translateY(1px)}
.btn:disabled{opacity:.42;cursor:not-allowed;transform:none}
.btn .arrow{transition:transform var(--move)}
.btn:hover .arrow{transform:translateX(3px)}
.btn:hover .arrow.back{transform:translateX(-3px)}
.pageNav{max-width:1120px;margin:0 auto;padding:12px 24px 0;display:flex;align-items:center;justify-content:space-between;gap:12px}
.pageNav[hidden]{display:none}
.pageNav .btn.next{background:var(--soft);border:1px solid transparent;color:var(--blue)}
.pageNav .btn.next:hover{background:#dce8ff}
body:has(.pageNav:not([hidden])) main{padding-top:20px}
.textLink{color:var(--blue);font-weight:600}
.textLink:hover{color:#345dcc}

.soundTitle{margin:0}
.soundButton{
  display:grid;place-items:center;
  min-width:108px;min-height:84px;padding:6px 20px;
  border:0;border-radius:18px;
  background:var(--tile);
  color:var(--text);
  font-family:"DejaVu Sans",Arial,sans-serif;
  font-size:clamp(2.15rem,3.4vw,3.1rem);font-weight:700;line-height:1;
  box-shadow:var(--shadow-soft);
  transition:transform var(--move),background var(--move),box-shadow var(--move);
}
.soundButton:hover{transform:translateY(-2px);background:var(--tile-hover);box-shadow:0 12px 22px rgba(15,23,42,.08)}
.soundButton.vowel{background:var(--vowel);color:var(--symbol)}
.soundButton.consonant{background:var(--consonant);color:var(--symbol)}
.soundButton.vowel:hover{background:var(--vowel-hover)}
.soundButton.consonant:hover{background:var(--consonant-hover)}
.soundButton:active,.soundButton.isPlaying{transform:translateY(2px)}

.visualGrid{display:grid;grid-template-columns:1fr 1fr;gap:16px;align-items:stretch}
.visualGrid.hasSequence{align-items:start}
.visualGrid.hasSequence .visualCard{height:auto}
.visualCard{display:flex;flex-direction:column;background:var(--card);border:1px solid var(--line);border-radius:18px;overflow:hidden;min-width:0;height:100%;box-shadow:var(--shadow)}
.visualCard h2{margin:0;padding:16px 18px 0;font-size:.95rem;font-weight:600;letter-spacing:.02em}
.visualFrame{height:260px;display:grid;place-items:center;overflow:hidden;background:#f3f6fb}
.visualFrame canvas{display:block;width:100%;height:100%;object-fit:contain}
.visualFrame.isSequence{height:auto;display:block}
.visualFrame.isSequence canvas{width:100%;height:auto;object-fit:contain}
.visualCard p{margin:0;padding:10px 18px 16px;color:var(--muted);font-size:.86rem}
.explainer{margin-top:20px;padding:24px}
.explainer h2{margin:18px 0 6px;color:var(--blue);font-size:1rem;font-weight:600;letter-spacing:.02em}
.explainer h2:first-child{margin-top:0}
.explainer p{margin:0 0 8px}
.note{color:var(--muted);font-size:.92rem}

.wordSection,.positionSection,.phraseSection,.drillContext{margin-top:20px;padding:24px}
.words{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}
.wordButton,.positionButton{
  position:relative;
  display:flex;flex-direction:column;align-items:flex-start;justify-content:center;gap:4px;
  min-height:96px;padding:14px 42px 14px 16px;
  border:1px solid var(--line);border-radius:14px;
  background:var(--wash);color:var(--text);text-align:left;
  box-shadow:none;
  transition:background var(--move),border-color var(--move),transform var(--move);
}
.wordButton:hover,.positionButton:hover,.phraseItem:hover{background:var(--soft);border-color:rgba(79,125,243,.35);transform:translateY(-2px)}
.wordButton:active,.positionButton:active,.phraseItem:active{transform:translateY(1px)}
.wordLabel{font-size:1.45rem;font-weight:600;line-height:1.2}
.wordIPA{color:var(--blue);font-family:"DejaVu Sans",Arial,sans-serif;font-size:1.02rem}
.wordPlay{position:absolute;right:14px;top:16px;color:var(--blue);transition:transform var(--move)}
.wordButton:hover .wordPlay,.positionButton:hover .wordPlay{transform:translateX(3px)}
.positions{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}
.positionLabel{display:block;color:var(--blue);font-size:.84rem;font-weight:600}
.noPosition{border:1px dashed rgba(100,116,139,.35);border-radius:14px;padding:14px;color:var(--muted);font-size:.9rem;background:#fff}
.feedback{min-height:1.5em;margin:12px 0 0;color:var(--blue);font-size:.92rem}

.practiceShell{max-width:860px;margin:auto}
.drill{padding:28px 22px 24px;text-align:center}
.drillNo{color:var(--blue);font-weight:600;letter-spacing:.06em;font-variant-numeric:tabular-nums}
.drillPhrase{max-width:100%;margin:14px auto 6px;font-size:clamp(1.35rem,4.6vw,2.35rem);line-height:1.35;font-weight:600;letter-spacing:.01em;text-wrap:balance;overflow-wrap:anywhere}
.drillTranslation{margin:0 auto 8px;color:var(--muted);font-size:clamp(1rem,2vw,1.2rem)}
.targetLetters{color:#be123c;font-weight:700;background:#fff1f2;border-radius:4px;padding:0 .08em}
.drillControls{display:flex;align-items:center;justify-content:center;gap:14px;margin-top:18px}
.playButton{
  width:64px;height:64px;flex:none;
  border:0;border-radius:50%;
  background:var(--blue);color:#fff;
  box-shadow:0 8px 18px rgba(79,125,243,.22);
  transition:transform var(--move),background var(--move);
}
.playButton::before{content:"";display:block;margin-left:4px;border-style:solid;border-width:9px 0 9px 15px;border-color:transparent transparent transparent #fff}
.playButton:hover{background:#3d6ae0;transform:translateY(-1px) scale(1.04)}
.playButton:active{transform:scale(.96)}
.phraseList{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.phraseItem{
  display:flex;align-items:flex-start;gap:10px;
  width:100%;min-height:76px;padding:12px 14px;
  border:1px solid var(--line);border-radius:14px;
  background:var(--wash);color:var(--text);text-align:left;
  transition:background var(--move),border-color var(--move),transform var(--move);
}
.phraseItem.selected{background:var(--soft);border-color:rgba(79,125,243,.55)}
.phraseNumber{flex:none;color:var(--blue);font-weight:600;font-variant-numeric:tabular-nums}
.phraseText{display:flex;flex-direction:column;gap:4px;min-width:0}
.phraseEnglish{line-height:1.4;overflow-wrap:anywhere}
.phraseTranslation{color:var(--muted);font-size:.94rem}
.drillContext p{margin:8px 0 0;color:var(--muted)}

@media(max-width:980px){
  .words{grid-template-columns:1fr 1fr}
}
@media(max-width:720px){
  .headerInner{display:flex;flex-direction:column;align-items:stretch;gap:10px;padding:12px 14px 10px}
  .brand{font-size:1rem}
  .topNav{display:flex;width:100%;max-width:100%;gap:4px}
  .navLink{flex:1 1 0px;width:auto;min-width:0;padding:8px 2px;text-align:center;font-size:13px;white-space:normal}
  .crumbBar{padding:8px 16px 0}
  .pageNav{padding:10px 16px 0}
  .pageNav .btn{padding:0 10px;font-size:.86rem;min-height:42px}
  main{padding:22px 16px 56px}
  .visualGrid{grid-template-columns:1fr}
  .section,.wordSection,.positionSection,.phraseSection,.drill{padding:16px}
  .grid{grid-template-columns:repeat(3,minmax(0,1fr));gap:10px}
  .tile{min-height:84px}
  .tileSymbol{font-size:2rem}
  .learnHead,.practiceTop{flex-direction:column;align-items:flex-start}
  .visualFrame{height:230px}
  .positions,.phraseList,.words{grid-template-columns:1fr}
  .drillControls{gap:10px}
  .siteFooter{padding:16px}
}
@media(hover:none){
  .tile:hover,.wordButton:hover,.positionButton:hover,.phraseItem:hover,.btn:hover,.soundButton:hover,.playButton:hover{transform:none}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .tile,.navLink,.btn,.soundButton,.wordButton,.positionButton,.phraseItem,.playButton,.wordPlay,.arrow{transition:none}
}