:root{color-scheme:light;
  --paper:#f7f5f0;
  --surface:#fffefa;
  --ink:#292c29;
  --muted:#62665f;
  --line:#dddcd3;
  --accent:#ad3e2d;
  --soft:#f8e9e2;
  --green:#286247;
  --blue:#335d88;
  font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans CJK SC","Microsoft YaHei",sans-serif;
  color:var(--ink);
  background:var(--paper);
  font-synthesis:none}
*{box-sizing:border-box}
[hidden]{display:none!important}
body{margin:0;
  font-size:16px;
  line-height:1.6}
button,input,select,textarea{font:inherit}
button,a,input,select,textarea{touch-action:manipulation}
button{cursor:pointer}
button,select,textarea{transition:background .15s,border-color .15s,box-shadow .15s}
button:disabled{cursor:default;
  opacity:.6}
a{color:inherit}
button{min-height:44px;
  border:1px solid var(--line);
  border-radius:12px;
  background:var(--surface);
  padding:10px 16px;
  color:var(--ink)}
button:hover:not(:disabled){background:#f0eee7;
  border-color:#aaa99f}
:focus-visible{outline:3px solid var(--blue);
  outline-offset:4px}
h1,h2,h3,p{margin-top:0}
h1{font-size:clamp(2.15rem,4.6vw,3.7rem);
  line-height:1.12;
  letter-spacing:-.045em;
  font-weight:650;
  margin-bottom:24px}
h2{font-size:1.45rem;
  line-height:1.3;
  letter-spacing:-.025em;
  margin-bottom:12px}
h3{font-size:1.1rem;
  line-height:1.6}
header,main,footer{max-width:1160px;
  margin:auto;
  padding-inline:32px}
header{display:flex;
  align-items:center;
  justify-content:space-between;
  gap:24px;
  padding-block:28px;
  border-bottom:1px solid var(--line)}
.brand{display:flex;
  gap:13px;
  align-items:center;
  text-decoration:none;
  font-size:1.45rem;
  font-weight:700;
  letter-spacing:-.03em}
.brand-mark{display:grid;
  place-items:center;
  width:48px;
  height:48px;
  border:1px solid var(--accent);
  border-radius:13px;
  color:var(--accent);
  font-size:30px;
  font-weight:400}
.brand small{display:block;
  font-size:.76rem;
  letter-spacing:.015em;
  color:var(--muted);
  font-weight:400}
.local{font-size:.75rem;
  color:var(--muted);
  max-width:150px;
  text-align:right}
.local:before{content:'●';
  color:var(--green);
  margin-right:6px;
  font-size:10px}
.intro{display:grid;
  grid-template-columns:1fr 260px;
  gap:60px;
  align-items:center;
  padding:64px 0 48px}
.intro p:not(.eyebrow){max-width:620px;
  color:var(--muted);
  font-size:1.05rem}
.intro .intro-secondary{font-size:.94rem!important;
  margin-bottom:0}
.eyebrow{font-size:.69rem;
  font-weight:700;
  letter-spacing:.15em;
  color:var(--accent);
  margin-bottom:18px}
.letter-study{padding:25px;
  text-align:center;
  border:1px solid var(--line);
  border-radius:100px 100px 20px 20px;
  background:linear-gradient(145deg,#eee9df,#f9f6ef);
  transform:rotate(3deg)}
.letter-study>span{font-family:"Noto Serif CJK SC","Songti SC",serif;
  font-size:130px;
  line-height:1.45;
  color:var(--accent)}
.letter-study div{font-size:18px}
.letter-study div span{font-size:12px;
  color:var(--muted);
  margin-left:10px}
.letter-study small{display:block;
  font-size:11px;
  margin-top:16px;
  color:var(--muted)}
.session-builder,.panel{border:1px solid var(--line);
  background:var(--surface);
  border-radius:24px;
  padding:32px}
.section-heading{display:flex;
  align-items:center;
  justify-content:space-between;
  gap:20px;
  margin-bottom:24px}
.section-heading h2,.section-heading .eyebrow{margin-bottom:6px}
.badge{border:1px solid var(--line);
  padding:5px 12px;
  border-radius:100px;
  font-size:.75rem;
  color:var(--muted);
  white-space:nowrap}
.builder-grid{display:grid;
  grid-template-columns:1fr 1.15fr;
  gap:32px}
.unit-panel{border-right:1px solid var(--line);
  padding-right:32px}
fieldset{border:0;
  padding:0;
  margin:0;
  min-width:0}
legend{font-weight:650;
  margin-bottom:16px;
  padding:0;
  font-size:1rem}
.step{font-size:12px;
  color:var(--accent);
  margin-right:10px}
.helper{font-size:.8rem;
  color:var(--muted);
  line-height:1.6}
.unit{display:flex;
  align-items:center;
  gap:14px;
  padding:16px;
  border:1px solid var(--line);
  border-radius:14px;
  margin-bottom:10px;
  cursor:pointer}
.unit:has(input:checked){background:var(--soft);
  border-color:var(--accent)}
input[type=checkbox]{accent-color:var(--accent);
  width:20px;
  height:20px;
  flex-shrink:0;
  margin:0}
.unit span{font-weight:650}
.unit small,.check small{display:block;
  font-weight:400;
  font-size:.77rem;
  color:var(--muted);
  margin-top:3px}
label{display:block;
  font-size:.85rem;
  font-weight:600}
select,textarea{display:block;
  width:100%;
  min-width:0;
  border:1px solid #aaa99f;
  border-radius:12px;
  color:var(--ink);
  background:var(--surface);
  padding:12px;
  margin:7px 0 12px;
  min-height:48px}
select{font-size:.9rem;
  padding-right:28px}
textarea{resize:vertical;
  font-size:1.2rem;
  line-height:1.8;
  padding:18px;
  min-height:136px}
textarea:focus{border-color:var(--accent);
  box-shadow:0 0 0 3px var(--soft)}
textarea:disabled{background:#f0efe9;
  color:#565a54}
.form-grid{display:grid;
  grid-template-columns:1.3fr 1fr;
  gap:16px}
.check{display:flex;
  gap:12px;
  align-items:center;
  cursor:pointer;
  padding:12px 0;
  font-weight:500}
.session-options{border-top:1px solid var(--line);
  margin-top:10px;
  padding-top:5px}
.start-row{display:flex;
  align-items:center;
  justify-content:space-between;
  gap:20px;
  border-top:1px solid var(--line);
  margin-top:28px;
  padding-top:24px}
.start-row p{font-size:.9rem;
  margin:0}
.start-row p span{font-size:.8rem;
  color:var(--muted)}
.primary{background:var(--accent);
  color:white;
  border-color:var(--accent);
  font-weight:600;
  padding:14px 22px;
  min-height:52px}
.primary:hover:not(:disabled){background:#8e3022;
  border-color:#8e3022}
.primary span{margin-left:22px}
.subtle{background:transparent;
  border-color:transparent;
  color:var(--muted);
  font-size:.8rem;
  padding:10px 6px;
  text-align:left}
.subtle:hover:not(:disabled){border-color:transparent;
  background:#eeece5;
  color:var(--ink)}
#setup-error:empty,#storage-message:empty,#feedback:empty{display:none}
#setup-error{color:#992d24;
  margin:16px 0 0}
.progress-section{padding:48px 0 32px}
#stats{display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:16px}
.stat{border-top:2px solid var(--line);
  padding:20px 4px}
.stat strong{font-size:1rem}
.stat p{font-size:.8rem;
  color:var(--muted);
  margin:8px 0}
.stat summary{font-size:.8rem;
  cursor:pointer;
  min-height:44px;
  padding:10px 0}
.stat details p{overflow-wrap:anywhere}
.learning-note{font-size:.76rem;
  color:var(--muted);
  border-top:1px solid var(--line);
  padding:24px 0;
  max-width:850px}
.learning-note strong{display:block;
  color:var(--ink);
  margin-bottom:4px}
footer{display:flex;
  gap:40px;
  justify-content:space-between;
  border-top:1px solid var(--line);
  padding-block:28px;
  color:var(--muted);
  font-size:.72rem}
footer strong{font-size:.95rem;
  color:var(--ink)}
footer p{max-width:560px;
  margin:8px 0 0}
footer>span{max-width:180px}
.exercise{max-width:820px;
  margin:40px auto;
  padding:32px 40px}
.session-meta{display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  color:var(--muted);
  font-size:.8rem}
.track{height:5px;
  background:#eeece5;
  border-radius:8px;
  margin:16px 0 32px;
  overflow:hidden}
#bar{height:100%;
  background:var(--accent);
  border-radius:8px;
  transition:width .2s}
.question-meta{display:flex;
  justify-content:space-between;
  align-items:center;
  gap:16px;
  margin-bottom:22px}
.question-meta .eyebrow{margin:0;
  letter-spacing:.07em}
#question{font-size:clamp(1.4rem,2.8vw,1.9rem);
  line-height:1.65;
  letter-spacing:-.015em;
  font-weight:550;
  margin-bottom:30px;
  overflow-wrap:anywhere}
.hanzi{font-size:1.2em;
  line-height:1.7;
  font-family:"Noto Sans CJK SC","PingFang SC","Microsoft YaHei",sans-serif}
#question:focus,#summary h1:focus{outline:none}
#answer-form label{font-weight:550;
  color:var(--muted)}
#parts label{margin-top:22px;
  color:var(--ink);
  font-size:1rem}
#options,.tokens{display:flex;
  flex-wrap:wrap;
  gap:8px;
  margin-bottom:16px}
.tokens small{flex-basis:100%;
  color:var(--muted)}
#options:empty,.tokens:empty{display:none}
#options button,.tokens button{font-size:1.1rem}
#submit{margin-top:8px}
.actions{display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:18px;
  margin-top:16px}
.actions #next{margin-left:auto;
  min-width:180px}
#feedback{margin-top:24px;
  line-height:1.7}
.feedback{border:1px solid var(--line);
  border-left:4px solid;
  border-radius:14px;
  padding:22px;
  margin:16px 0;
  overflow-wrap:anywhere}
.feedback>strong{display:block;
  font-size:.78rem;
  letter-spacing:.06em;
  margin-bottom:10px}
.feedback>strong:before{display:inline-block;
  width:24px;
  font-size:1rem}
.feedback.correct{border-left-color:var(--green);
  background:#eef5ee}
.feedback.correct>strong{color:#235239}
.feedback.correct>strong:before{content:'✓'}
.feedback.incorrect{border-left-color:var(--accent);
  background:#fbede6}
.feedback.incorrect>strong{color:#8e3022}
.feedback.incorrect>strong:before{content:'×'}
.feedback.unrecognized{border-left-color:var(--blue);
  background:#edf2f7}
.feedback.unrecognized>strong{color:#294c70}
.feedback.unrecognized>strong:before{content:'?'}
.feedback p{font-size:.9rem;
  margin-bottom:12px}
.feedback p:last-child{margin-bottom:0}
.feedback .reference{background:#ffffffa8;
  padding:16px;
  border-radius:9px;
  color:var(--ink)}
.reference .hanzi{font-size:1.5rem}
.feedback .feedback{background:#ffffff80}
.feedback small{font-size:.75rem}
body[data-view=exercise] .progress-section,body[data-view=exercise] .learning-note{display:none}
#summary{margin:40px auto;
  max-width:920px}
.summary-heading{max-width:650px}
.summary-heading h1{font-size:2.6rem}
.summary-heading p:not(.eyebrow){color:var(--muted)}
.metrics{display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:12px;
  margin:28px 0 16px}
.metrics>div{padding:22px;
  border:1px solid var(--line);
  border-radius:14px}
.metrics strong{display:block;
  font-size:2.2rem;
  font-weight:600}
.metrics span{font-size:.8rem}
.metrics>div:nth-child(1){background:#eef5ee;
  color:#235239}
.metrics>div:nth-child(2){background:#fbede6;
  color:#8e3022}
.metrics>div:nth-child(3){background:#edf2f7;
  color:#294c70}
#summary>h2{margin-top:32px}
#unit-results{display:grid;
  gap:10px}
.unit-result{padding:16px 18px;
  background:var(--paper);
  border-radius:12px;
  display:flex;
  justify-content:space-between;
  gap:12px;
  font-size:.85rem}
.unit-result p{margin:0;
  color:var(--muted)}
#concept-review{font-size:.9rem;
  color:var(--muted)}
#concept-review ul{padding-left:20px}
#concept-review li{margin-bottom:8px}
.review-heading{border-top:1px solid var(--line);
  margin-top:32px;
  padding-top:28px}
#review>p{font-size:.8rem;
  color:var(--muted)}
#review article{border-top:1px solid var(--line);
  padding-top:24px;
  margin-top:24px}
#review article>p{font-size:.9rem;
  overflow-wrap:anywhere}
.skip-link{position:absolute;
  left:16px;
  top:-100px;
  z-index:10;
  background:var(--ink);
  color:white;
  padding:12px}
.skip-link:focus{top:8px}

@media(max-width:800px){header,main,footer{padding-inline:24px}
.intro{grid-template-columns:1fr 180px;
  gap:24px;
  padding-block:40px}
.letter-study>span{font-size:95px}
.builder-grid{grid-template-columns:1fr;
  gap:24px}
.unit-panel{border:0;
  border-bottom:1px solid var(--line);
  padding:0 0 20px}
#units{display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:10px}
.unit{align-items:flex-start;
  padding:12px;
  gap:8px}
.unit small{font-size:.7rem}
.unit input{width:18px;
  height:18px;
  margin-top:3px}
.exercise{padding:28px}
.question-meta{align-items:flex-start}
.unit-result{display:block}
.unit-result p{margin-top:5px}
}

@media(max-width:540px){header,main,footer{padding-inline:20px}
header{padding-block:20px}
.brand{font-size:1.25rem;
  gap:10px}
.brand small{font-size:.65rem}
.brand-mark{width:40px;
  height:44px;
  font-size:27px}
.local{display:none}
.intro{display:block;
  padding:36px 0 28px}
.intro h1{font-size:2.3rem}
.intro p:not(.eyebrow){font-size:.94rem}
.intro .intro-secondary{font-size:.85rem!important}
.letter-study{display:none}
.eyebrow{font-size:.65rem}
.session-builder,.panel{padding:20px;
  border-radius:18px}
.section-heading{gap:10px;
  align-items:flex-start}
.section-heading h2{font-size:1.3rem}
.section-heading>.badge{display:none}
#units{display:block}
.unit{align-items:center;
  padding:14px;
  gap:12px}
.unit small{font-size:.77rem}
.form-grid{grid-template-columns:1fr;
  gap:4px}
.start-row{display:block;
  margin-top:20px;
  padding-top:20px}
.start-row p{margin-bottom:18px}
.start-row .primary{width:100%;
  display:flex;
  justify-content:space-between;
  align-items:center}
.progress-section{padding-top:32px}
#stats{grid-template-columns:1fr;
  gap:0}
.progress-section .section-heading{align-items:center}
.progress-section #erase{max-width:120px;
  text-align:right}
.stat{padding:16px 4px}
.exercise{margin:24px auto}
.session-meta{font-size:.72rem;
  align-items:flex-start}
.session-meta .subtle{font-size:.72rem;
  padding-top:0;
  min-width:95px;
  text-align:right}
.track{margin-top:8px;
  margin-bottom:24px}
.question-meta{gap:8px;
  flex-wrap:wrap}
.question-meta .badge{font-size:.68rem}
#question{font-size:1.35rem;
  line-height:1.7;
  margin-bottom:24px}
textarea{font-size:1.1rem;
  padding:14px;
  min-height:145px}
#submit{width:100%}
.actions{gap:8px;
  justify-content:space-between}
.actions #next{width:100%}
.feedback{padding:16px}
.feedback .feedback{padding:12px}
.feedback .reference{padding:12px}
.metrics{gap:6px}
.metrics>div{padding:12px 8px}
.metrics strong{font-size:1.8rem}
.metrics span{font-size:.68rem}
.summary-heading h1{font-size:2.1rem}
.review-heading{flex-direction:column}
.review-heading button{width:100%;
  margin-top:10px}
footer{flex-direction:column;
  gap:18px}
footer>span{max-width:none}
.learning-note{font-size:.72rem}
}

@media(prefers-reduced-motion:reduce){*,*::before,*::after{transition:none!important;
  scroll-behavior:auto!important}
}