:root{
  box-sizing:border-box;
  padding-top:env(safe-area-inset-top,0px);
  padding-bottom:env(safe-area-inset-bottom,0px);
  /* palette: warm paper + Vietnamese lacquer red + jade */
  --paper:#f6f3ec;
  --card:#fffdf7;
  --ink:#26221c;
  --ink-soft:#6a6156;
  --line:#e4ddcf;
  --line-strong:#d6cdb9;
  --red:#b3231d;
  --red-soft:#f3e0dd;
  --jade:#1f7a6d;
  --jade-soft:#dcece9;
  --gold:#b58a2e;
  --shadow:0 1px 0 rgba(38,34,28,.04);
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --paper:#1a1713; --card:#231f19; --ink:#efe8db; --ink-soft:#b3a894;
    --line:#332d24; --line-strong:#443c30; --red:#e2665f; --red-soft:#3a201e;
    --jade:#68c0b1; --jade-soft:#1c2c2a; --gold:#d8ab4e; --shadow:none;
  }
}
:root[data-theme="dark"]{
  --paper:#1a1713; --card:#231f19; --ink:#efe8db; --ink-soft:#b3a894;
  --line:#332d24; --line-strong:#443c30; --red:#e2665f; --red-soft:#3a201e;
  --jade:#68c0b1; --jade-soft:#1c2c2a; --gold:#d8ab4e; --shadow:none;
}
*{box-sizing:border-box}
html{scroll-padding-top:env(safe-area-inset-top,0px)}
body{
  margin:0;background:var(--paper);color:var(--ink);
  font-family:"Be Vietnam Pro",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  font-size:16px;line-height:1.5;-webkit-font-smoothing:antialiased;
}
.app{max-width:720px;margin:0 auto;padding:0 18px 120px;position:relative}

/* topbar */
.topbar{display:flex;align-items:flex-end;justify-content:space-between;gap:16px;
  padding:22px 0 16px;position:sticky;top:env(safe-area-inset-top,0px);z-index:20;
  background:linear-gradient(var(--paper) 78%,rgba(246,243,236,0));
}
.eyebrow{font-size:11px;letter-spacing:.16em;color:var(--red);font-weight:600}
.topbar h1{font-family:"Lora",Georgia,serif;font-weight:600;font-size:26px;margin:2px 0 0;line-height:1}
.ghost{border:1px solid var(--line-strong);background:transparent;color:var(--ink-soft);
  font:inherit;font-size:13px;padding:7px 13px;border-radius:999px;cursor:pointer}
.ghost:hover{border-color:var(--red);color:var(--red)}

/* screens */
.screen{display:none}
.screen.active{display:block;animation:fade .18s ease}
@keyframes fade{from{opacity:0}to{opacity:1}}
@media (prefers-reduced-motion:reduce){.screen.active{animation:none}}

/* hero */
.hero{background:var(--card);border:1px solid var(--line);border-radius:16px;
  padding:22px 20px;box-shadow:var(--shadow);position:relative;overflow:hidden}
.hero::after{content:"越";position:absolute;right:-10px;bottom:-26px;font-size:120px;
  font-family:"Lora",serif;color:var(--red);opacity:.06;line-height:1}
.hero .pill{display:inline-block;font-size:11px;letter-spacing:.06em;font-weight:600;
  color:var(--red);background:var(--red-soft);padding:4px 11px;border-radius:999px}
.hero h2{font-family:"Lora",serif;font-weight:600;font-size:24px;margin:12px 0 6px}
.hero p{margin:0;color:var(--ink-soft);max-width:46ch}

/* progress */
.progress-card{margin-top:14px;background:var(--card);border:1px solid var(--line);
  border-radius:14px;padding:14px 16px;box-shadow:var(--shadow)}
.progress-head{display:flex;justify-content:space-between;align-items:baseline;font-size:14px}
.progress-head strong{font-weight:600}
.progress-head span{color:var(--ink-soft);font-size:13px}
.bar{height:8px;background:var(--line);border-radius:999px;margin-top:10px;overflow:hidden}
.bar>div{height:100%;width:0;background:var(--jade);border-radius:999px;transition:width .35s ease}
@media (prefers-reduced-motion:reduce){.bar>div{transition:none}}

/* section heading in dashboard */
.rowhead{margin:26px 2px 12px;font-size:13px;letter-spacing:.02em;color:var(--ink-soft);font-weight:600}

/* day cards */
.days{display:grid;gap:11px}
.day{text-align:left;width:100%;cursor:pointer;background:var(--card);
  border:1px solid var(--line);border-left:3px solid var(--line-strong);
  border-radius:13px;padding:15px 16px;font:inherit;color:var(--ink);
  display:flex;align-items:center;gap:14px;box-shadow:var(--shadow)}
.day:hover{border-left-color:var(--red)}
.day .num{font-family:"Lora",serif;font-size:22px;font-weight:600;color:var(--red);
  min-width:30px;text-align:center}
.day .meta{flex:1;min-width:0}
.day .meta h3{margin:0;font-size:15px;font-weight:600}
.day .meta p{margin:2px 0 0;font-size:13px;color:var(--ink-soft);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.day .tick{width:22px;height:22px;border-radius:50%;border:1.5px solid var(--line-strong);
  display:grid;place-items:center;font-size:12px;color:transparent;flex-shrink:0}
.day.done{border-left-color:var(--jade)}
.day.done .tick{background:var(--jade);border-color:var(--jade);color:#fff}

/* lesson */
.back{background:none;border:none;font:inherit;color:var(--red);font-weight:600;
  cursor:pointer;padding:4px 0;font-size:14px}
.lesson-head{margin:6px 0 4px}
.lesson-head .pill{display:inline-block;font-size:11px;letter-spacing:.06em;font-weight:600;
  color:var(--red);background:var(--red-soft);padding:4px 11px;border-radius:999px}
.lesson-head h2{font-family:"Lora",serif;font-weight:600;font-size:26px;margin:12px 0 4px}
.lesson-head .goal{color:var(--ink-soft);margin:0}
.lesson-head .goal b{color:var(--ink)}

.section{margin-top:22px}
.section>h3{font-size:15px;font-weight:600;margin:0 0 10px;display:flex;align-items:center;gap:8px}
.section>h3::before{content:"";width:14px;height:2px;background:var(--red);border-radius:2px}
.section .p{color:var(--ink-soft);margin:0 0 10px}

pre.mindmap{background:var(--card);border:1px solid var(--line);border-radius:12px;
  padding:14px;overflow-x:auto;font-size:12.5px;line-height:1.45;color:var(--ink);
  font-family:ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;box-shadow:var(--shadow)}

.vocab-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:9px}
.vocab{background:var(--card);border:1px solid var(--line);border-radius:11px;padding:11px 13px;box-shadow:var(--shadow)}
.vocab strong{display:block;font-size:17px;color:var(--red);font-weight:600}
.vocab small{color:var(--ink-soft);font-size:13px;line-height:1.35;display:block;margin-top:2px}

.number-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(88px,1fr));gap:8px}
.number{background:var(--card);border:1px solid var(--line);border-radius:11px;padding:10px;text-align:center;box-shadow:var(--shadow)}
.number b{display:block;font-size:16px;color:var(--red)}
.number small{color:var(--ink-soft)}
.vocab,.number{position:relative}
.say{position:absolute;top:7px;right:7px;width:26px;height:26px;border:1px solid var(--line);background:var(--card);border-radius:8px;cursor:pointer;font-size:13px;line-height:1;padding:0;color:var(--ink-soft)}
.say:hover{border-color:var(--red);color:var(--red)}
.say:active{transform:scale(.92)}
.dialog .say,.say-all{position:static;display:inline-grid;place-items:center;width:24px;height:22px;vertical-align:middle;margin-left:5px}
@media (prefers-reduced-motion:reduce){.say:active{transform:none}}
.say-lg{font-size:15px;padding:12px 18px;display:inline-flex;align-items:center;gap:6px}
.listen-audio .vn-line{font-family:"Lora",Georgia,serif;font-size:16px;line-height:1.85;margin:0}
.listen-audio details.ex{margin-top:12px}
.la-controls{margin-top:8px;display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.la-lines{display:flex;flex-wrap:wrap;gap:8px;margin-top:12px}
.say-line{position:static;display:inline-flex;align-items:center;gap:4px;width:auto;height:auto;padding:7px 12px;border-radius:999px;font-size:13px}

.pattern{background:var(--card);border:1px solid var(--line);border-radius:12px;
  padding:13px 15px;margin-bottom:10px;box-shadow:var(--shadow)}
.pattern .formula{font-family:"Lora",serif;font-size:17px;font-weight:600;margin-bottom:7px}
.pattern .formula b{color:var(--red)}
.pattern .examples{color:var(--ink);line-height:1.7}
.pattern .gloss,.pattern p{color:var(--ink-soft);margin:5px 0 0;font-style:italic;font-family:"Lora",serif}

.dialog{background:var(--jade-soft);border:1px solid var(--line);border-radius:12px;
  padding:14px 16px;line-height:1.85;color:var(--ink);font-size:15px}
.dialog b{color:var(--jade);font-weight:600}

.note{background:transparent;border:1px dashed var(--line-strong);border-radius:11px;
  padding:11px 14px;margin-top:12px;color:var(--ink-soft);font-size:14px;line-height:1.55}
.note b{color:var(--ink)}

details.ex{background:var(--card);border:1px solid var(--line);border-radius:12px;
  padding:0;margin-bottom:10px;box-shadow:var(--shadow);overflow:hidden}
details.ex>summary{list-style:none;cursor:pointer;padding:13px 15px;font-weight:600;font-size:14.5px;
  display:flex;justify-content:space-between;align-items:center}
details.ex>summary::-webkit-details-marker{display:none}
details.ex>summary .caret{color:var(--ink-soft);font-weight:400;transition:transform .2s}
details.ex[open]>summary .caret{transform:rotate(90deg)}
details.ex .exbody{padding:0 15px 14px;color:var(--ink)}
details.ex .exbody .task{color:var(--ink-soft);margin:0 0 8px}
details.ex .answers{margin-top:10px;border-top:1px dashed var(--line-strong);padding-top:10px;font-size:14px}
details.ex .answers .lbl{color:var(--jade);font-weight:600;font-size:12px;letter-spacing:.04em}
@media (prefers-reduced-motion:reduce){details.ex>summary .caret{transition:none}}

.mission{background:var(--red);color:#fff;border-radius:12px;padding:15px 17px;line-height:1.55}
.mission .lbl{font-size:11px;letter-spacing:.1em;font-weight:600;opacity:.85;display:block;margin-bottom:5px}
.mission b{color:#fff;font-weight:700}

.review-card{background:var(--card);border:1px solid var(--line);border-radius:12px;
  padding:14px 16px;box-shadow:var(--shadow)}
.review-card ol,.review-card ul{margin:0;padding-left:20px;line-height:1.7}
.review-card .cols{display:grid;grid-template-columns:1fr 1fr;gap:10px 22px}
@media (max-width:460px){.review-card .cols{grid-template-columns:1fr}}
.review-card h4{margin:0 0 6px;font-size:13px;color:var(--ink-soft);font-weight:600}

.donebar{margin-top:26px;display:flex;gap:10px}
.lesson-nav{margin-top:12px;display:flex;gap:10px}
.lesson-nav .btn[disabled]{opacity:.4;cursor:not-allowed}
.lesson-nav #nextBtn{text-align:right}
.kofi{display:inline-flex;align-items:center;gap:6px;background:#13C3FF;color:#023;text-decoration:none;font-weight:700;border-radius:999px;padding:10px 18px;font-size:14px;border:1px solid rgba(0,0,0,.06)}
.kofi.big{padding:12px 22px;font-size:15px}
.kofi:hover{filter:brightness(1.05)}
.support-card{margin-top:22px;background:var(--card);border:1px solid var(--line);border-radius:14px;padding:18px;box-shadow:var(--shadow);text-align:center}
.support-card p{margin:0 0 12px;color:var(--ink)}
.aff-box{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:13px 15px;box-shadow:var(--shadow)}
.aff-list{display:grid;gap:10px}
a.aff{color:var(--jade);font-weight:600;text-decoration:none}
a.aff:hover{text-decoration:underline}
.aff-note{display:block;margin-top:10px;color:var(--ink-soft);font-size:12px;line-height:1.5}
#dashSupport:empty{display:none}
.btn{flex:1;font:inherit;font-weight:600;font-size:15px;border-radius:12px;padding:13px;cursor:pointer;border:1px solid var(--line-strong);background:var(--card);color:var(--ink)}
.btn.primary{background:var(--jade);border-color:var(--jade);color:#fff}
.btn.primary.is-done{background:var(--card);color:var(--jade);border-color:var(--jade)}

/* flashcards */
.fc-wrap{max-width:420px;margin:8px auto 0}
.fc{perspective:1200px;margin-top:10px}
.fc-inner{position:relative;height:220px;cursor:pointer;transition:transform .5s;transform-style:preserve-3d}
.fc.flipped .fc-inner{transform:rotateY(180deg)}
@media (prefers-reduced-motion:reduce){.fc-inner{transition:none}}
.fc-face{position:absolute;inset:0;backface-visibility:hidden;background:var(--card);
  border:1px solid var(--line);border-radius:16px;display:grid;place-items:center;
  text-align:center;padding:20px;box-shadow:var(--shadow)}
.fc-face .big{font-family:"Lora",serif;font-size:32px;font-weight:600;color:var(--red)}
.fc-face.back{transform:rotateY(180deg)}
.fc-face.back .big{color:var(--ink)}
.fc-face .tag{position:absolute;top:12px;left:14px;font-size:11px;letter-spacing:.1em;color:var(--ink-soft)}
.fc-controls{display:flex;gap:10px;margin-top:14px}
.fc-count{text-align:center;color:var(--ink-soft);font-size:13px;margin-top:12px}

/* bottom nav */
.bottom{position:fixed;left:0;right:0;bottom:0;z-index:30;
  padding:8px 0 calc(8px + env(safe-area-inset-bottom,0px));
  background:var(--card);border-top:1px solid var(--line);
  display:flex;max-width:720px;margin:0 auto}
.bottom button{flex:1;background:none;border:none;font:inherit;color:var(--ink-soft);
  cursor:pointer;display:flex;flex-direction:column;align-items:center;gap:3px;font-size:11px;padding:4px}
.bottom button .ic{font-size:19px;line-height:1}
.bottom button.on{color:var(--red)}