/* Layout: a quiet reading column (~68ch) on cool paper; one lacquer-black hero band
   with gold leaf type is the single bold moment, echoing Thai lacquerware (ลายรดน้ำ). */
:root {
  --paper: #EEF0F2;
  --sheet: #FFFFFF;
  --ink: #17191E;
  --muted: #5A6070;
  --rule: #D7DBE1;
  --lacquer: #9C1C24;
  --lacquer-ink: #FFFFFF;
  --gold: #8C6719;
  --gold-wash: #F5ECD4;
  --hero-bg: #151215;
  --hero-ink: #F3EEE6;
  --hero-gold: #D9B45E;
  --hero-muted: #ABA39F;
  --ok: #1D7347;
  --ok-wash: #E3F2EA;
  --bad: #B42318;
  --bad-wash: #FBE8E6;
  --f-thai: "Noto Serif Thai", "Thonburi", "Leelawadee UI", Tahoma, serif;
  --f-ui: "IBM Plex Sans Thai Looped", "Noto Sans Thai", system-ui, sans-serif;
  --f-display: "Young Serif", Georgia, "Times New Roman", serif;
  --f-body: "Source Serif 4", Georgia, "Times New Roman", serif;
  --f-mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;
  --r: 10px;
  --shadow: 0 1px 2px rgb(20 18 22 / .06), 0 10px 28px rgb(20 18 22 / .07);
  --measure: 68ch;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0F0E10; --sheet: #19171A; --ink: #ECE7E1; --muted: #A49D99; --rule: #312C30;
    --lacquer: #E2585C; --lacquer-ink: #1A0B0C; --gold: #D6B160; --gold-wash: #2C2416;
    --hero-bg: #1D181B; --hero-ink: #F3EEE6; --hero-gold: #DDB862; --hero-muted: #ABA39F;
    --ok: #5CC28D; --ok-wash: #142A1F; --bad: #F2867C; --bad-wash: #331614;
    --shadow: 0 1px 2px rgb(0 0 0 / .4), 0 10px 28px rgb(0 0 0 / .35);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0F0E10; --sheet: #19171A; --ink: #ECE7E1; --muted: #A49D99; --rule: #312C30;
  --lacquer: #E2585C; --lacquer-ink: #1A0B0C; --gold: #D6B160; --gold-wash: #2C2416;
  --hero-bg: #1D181B; --hero-ink: #F3EEE6; --hero-gold: #DDB862; --hero-muted: #ABA39F;
  --ok: #5CC28D; --ok-wash: #142A1F; --bad: #F2867C; --bad-wash: #331614;
  --shadow: 0 1px 2px rgb(0 0 0 / .4), 0 10px 28px rgb(0 0 0 / .35);
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 400 17px/1.6 var(--f-body);
  -webkit-font-smoothing: antialiased;
}
body::before {
  content: ""; position: fixed; inset: 0 0 auto; height: env(safe-area-inset-top, 0px);
  z-index: 30; background: var(--sheet);
}
a { color: var(--lacquer); text-underline-offset: 3px; }
h1, h2, h3 { text-wrap: balance; margin: 0; }
p { margin: 0; }
button { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--gold); outline-offset: 2px; border-radius: 4px; }
.th { font-family: var(--f-thai); }
.mono { font-family: var(--f-mono); font-variant-numeric: tabular-nums; }
.wrap {
  max-width: 1080px; margin: 0 auto;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}
.col { max-width: 760px; margin: 0 auto; }
.eyebrow {
  font: 600 12px/1.2 var(--f-ui); letter-spacing: .12em; text-transform: uppercase; color: var(--gold);
}

/* ── Top bar ── */
.topbar {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 20;
  background: color-mix(in srgb, var(--sheet) 92%, transparent);
  backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1px solid var(--rule);
}
.topbar .wrap { display: flex; align-items: center; gap: 12px; min-height: 58px; }
.brand { display: flex; align-items: baseline; gap: 8px; text-decoration: none; color: var(--ink); margin-right: auto; }
.brand b { font: 400 22px/1 var(--f-display); letter-spacing: -.01em; }
.brand span { font: 600 15px/1 var(--f-thai); color: var(--lacquer); }
.nav { display: flex; gap: 4px; align-items: center; }
.nav a { font: 500 14px/1 var(--f-ui); color: var(--muted); text-decoration: none; padding: 9px 10px; border-radius: 8px; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--ink); background: var(--paper); }
@media (max-width: 560px) { .hide-sm { display: none !important; } .brand b { font-size: 19px; } }

/* ── Buttons ── */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font: 600 15px/1 var(--f-ui); padding: 13px 18px; border-radius: 999px;
  border: 1px solid var(--rule); background: var(--sheet); color: var(--ink);
  text-decoration: none; cursor: pointer; transition: transform .12s ease, background .12s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn-primary { background: var(--lacquer); border-color: var(--lacquer); color: var(--lacquer-ink); }
.btn-gold { background: var(--hero-gold); border-color: var(--hero-gold); color: #1A1408; }
.btn-ghost-dark { background: transparent; border-color: rgb(255 255 255 / .28); color: var(--hero-ink); }
.btn-small { padding: 9px 13px; font-size: 14px; }
.btn[disabled] { opacity: .55; cursor: default; transform: none; }
.linkish { background: none; border: 0; padding: 0; color: var(--lacquer); cursor: pointer; font: 600 14px/1.4 var(--f-ui); text-decoration: underline; text-underline-offset: 3px; }

/* ── Hero (lacquer band) ── */
.hero { background: var(--hero-bg); color: var(--hero-ink); position: relative; overflow: hidden; }
.hero::before, .hero::after {
  content: ""; position: absolute; left: 0; right: 0; height: 6px;
  background: repeating-linear-gradient(90deg, var(--hero-gold) 0 14px, transparent 14px 20px);
  opacity: .55;
}
.hero::before { top: 14px; } .hero::after { bottom: 14px; }
.hero .wrap { padding-block: 64px 60px; display: grid; grid-template-columns: 1.05fr 1fr; gap: 48px; align-items: center; }
@media (max-width: 880px) { .hero .wrap { grid-template-columns: 1fr; gap: 32px; padding-block: 48px; } }
.hero .eyebrow { color: var(--hero-gold); }
.hero h1 { font: 700 clamp(38px, 6vw, 60px)/1.25 var(--f-thai); color: var(--hero-gold); margin-top: 14px; }
.hero h1 + p { font: 400 19px/1.55 var(--f-body); color: var(--hero-ink); margin-top: 16px; max-width: 46ch; }
.hero .cta { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; }
.hero .fine { font: 400 13px/1.5 var(--f-ui); color: var(--hero-muted); margin-top: 14px; }

.tryit { background: rgb(255 255 255 / .04); border: 1px solid rgb(217 180 94 / .35); border-radius: 14px; padding: 22px; min-width: 0; }
.tryit .label { font: 600 12px/1 var(--f-ui); letter-spacing: .1em; text-transform: uppercase; color: var(--hero-muted); display: flex; justify-content: space-between; gap: 8px; }
.tryit .sent { font: 400 23px/2 var(--f-thai); margin-top: 12px; color: var(--hero-ink); }
.tryit .gloss { margin-top: 14px; background: var(--hero-ink); color: #17191E; border-radius: 10px; padding: 14px 16px; }
.tryit .gloss .w { font: 700 22px/1.3 var(--f-thai); color: #8A1A20; }
.tryit .gloss .m { font: 600 15px/1.4 var(--f-ui); margin-top: 2px; }
.tryit .gloss .n { font: 400 14px/1.5 var(--f-body); color: #4D5260; margin-top: 4px; }
.tryit .en { font: italic 400 15px/1.5 var(--f-body); color: var(--hero-muted); margin-top: 12px; }

/* tappable words */
.tw { cursor: pointer; border-radius: 4px; transition: background .1s ease; -webkit-tap-highlight-color: transparent; }
.tw:hover { background: rgb(217 180 94 / .22); }
.tw.on { background: var(--hero-gold); color: #1A1408; }
.reader .tw:hover { background: var(--gold-wash); }
.reader .tw.on { background: var(--gold-wash); box-shadow: inset 0 -2px 0 var(--gold); color: inherit; }

/* ── Sections ── */
.section { padding-block: 64px; }
.section + .section { border-top: 1px solid var(--rule); }
.section h2 { font: 400 clamp(28px, 4vw, 38px)/1.15 var(--f-display); margin-top: 8px; }
.section .lede { color: var(--muted); max-width: 60ch; margin-top: 10px; }

.steps { list-style: none; margin: 32px 0 0; padding: 0; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0; border-top: 1px solid var(--rule); }
@media (max-width: 820px) { .steps { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 520px) { .steps { grid-template-columns: 1fr; } }
.steps li { padding: 22px 22px 24px 0; border-bottom: 1px solid var(--rule); display: grid; grid-template-columns: 40px 1fr; gap: 4px 10px; align-content: start; }
.steps .k { font: 500 13px/1.6 var(--f-mono); color: var(--gold); grid-row: span 3; }
.steps .t { font: 600 16px/1.35 var(--f-ui); }
.steps .tt { font: 400 15px/1.4 var(--f-thai); color: var(--lacquer); }
.steps .d { font: 400 15px/1.5 var(--f-body); color: var(--muted); margin-top: 4px; }

.lessons { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; margin-top: 28px; }
@media (max-width: 720px) { .lessons { grid-template-columns: 1fr; } }
.lcard {
  display: flex; flex-direction: column; gap: 10px; text-decoration: none; color: inherit;
  background: var(--sheet); border: 1px solid var(--rule); border-radius: 14px; padding: 22px; box-shadow: var(--shadow);
  transition: transform .14s ease, border-color .14s ease; min-width: 0;
}
.lcard:hover { transform: translateY(-2px); border-color: var(--gold); }
.lcard .row { display: flex; justify-content: space-between; align-items: center; gap: 10px; flex-wrap: wrap; }
.tag { font: 600 12px/1 var(--f-ui); letter-spacing: .04em; padding: 6px 9px; border-radius: 999px; background: var(--paper); color: var(--muted); }
.tag.free { background: var(--ok-wash); color: var(--ok); }
.tag.lock { background: var(--gold-wash); color: var(--gold); }
.lcard h3 { font: 700 22px/1.5 var(--f-thai); }
.lcard .en { font: italic 400 16px/1.45 var(--f-body); color: var(--muted); }
.lcard .meta { font: 400 13px/1.5 var(--f-ui); color: var(--muted); margin-top: auto; padding-top: 10px; border-top: 1px dashed var(--rule); display: flex; flex-wrap: wrap; gap: 4px 14px; }
.lcard .meta b { font: 500 13px/1.5 var(--f-mono); color: var(--ink); }
.lcard.teaser { background: transparent; box-shadow: none; border-style: dashed; justify-content: center; cursor: pointer; text-align: left; font: inherit; }

/* ── Pricing ── */
.plans { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; margin-top: 28px; max-width: 820px; }
@media (max-width: 640px) { .plans { grid-template-columns: 1fr; } }
.plan { background: var(--sheet); border: 1px solid var(--rule); border-radius: 16px; padding: 26px; display: flex; flex-direction: column; gap: 14px; position: relative; }
.plan.best { border: 2px solid var(--lacquer); }
.plan .badge { position: absolute; top: -12px; left: 24px; background: var(--lacquer); color: var(--lacquer-ink); font: 600 12px/1 var(--f-ui); padding: 7px 10px; border-radius: 999px; letter-spacing: .03em; }
.plan .name { font: 600 15px/1 var(--f-ui); color: var(--muted); }
.plan .price { display: flex; align-items: baseline; gap: 6px; }
.plan .price b { font: 400 46px/1 var(--f-display); }
.plan .price span { font: 500 15px/1 var(--f-ui); color: var(--muted); }
.plan .sub { font: 400 14px/1.4 var(--f-ui); color: var(--muted); min-height: 1.4em; }
.plan ul { list-style: none; padding: 0; margin: 4px 0 6px; display: grid; gap: 8px; font: 400 15px/1.45 var(--f-ui); }
.plan li { display: grid; grid-template-columns: 18px 1fr; gap: 8px; }
.plan li::before { content: ""; width: 10px; height: 10px; margin-top: 6px; border-radius: 2px; background: var(--gold); transform: rotate(45deg); }
.plan .btn { margin-top: auto; }
.price-note { font: 400 13px/1.5 var(--f-ui); color: var(--muted); margin-top: 16px; max-width: 70ch; }

/* ── FAQ ── */
.faq { margin-top: 24px; max-width: 760px; border-top: 1px solid var(--rule); }
.faq details { border-bottom: 1px solid var(--rule); }
.faq summary { cursor: pointer; padding: 18px 0; font: 600 17px/1.4 var(--f-ui); list-style: none; display: flex; justify-content: space-between; gap: 16px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font: 400 22px/1 var(--f-mono); color: var(--gold); }
.faq details[open] summary::after { content: "–"; }
.faq details p { padding: 0 0 18px; color: var(--muted); max-width: 64ch; }

.footer { border-top: 1px solid var(--rule); background: var(--sheet); }
.footer .wrap { padding-block: 32px 40px; display: grid; gap: 10px; font: 400 13px/1.6 var(--f-ui); color: var(--muted); }
.footer .links { display: flex; flex-wrap: wrap; gap: 16px; }
.footer a { color: var(--muted); }

/* ── Reader ── */
.reader { background: var(--sheet); min-height: 70vh; }
.lhead { padding-block: 40px 28px; border-bottom: 1px solid var(--rule); }
.lhead .back { font: 500 14px/1 var(--f-ui); color: var(--muted); text-decoration: none; display: inline-block; margin-bottom: 22px; }
.lhead h1 { font: 700 clamp(28px, 4.6vw, 40px)/1.45 var(--f-thai); margin-top: 10px; }
.lhead .sub { font: italic 400 19px/1.45 var(--f-body); color: var(--muted); margin-top: 6px; }
.metabox { margin-top: 22px; display: grid; grid-template-columns: max-content 1fr; gap: 6px 16px; font: 400 14px/1.55 var(--f-ui); padding: 16px 18px; border-radius: var(--r); background: var(--paper); }
.metabox dt { color: var(--muted); }
.metabox dd { margin: 0; min-width: 0; overflow-wrap: anywhere; }
.metabox dd.th { font: 400 15px/1.6 var(--f-thai); }
@media (max-width: 520px) { .metabox { grid-template-columns: 1fr; } .metabox dd { margin-bottom: 8px; } }

.tabs {
  position: sticky; top: calc(env(safe-area-inset-top, 0px) + 58px); z-index: 15;
  background: color-mix(in srgb, var(--sheet) 94%, transparent); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--rule);
}
.tabs .tabrow { display: flex; gap: 2px; overflow-x: auto; scrollbar-width: none; margin-left: -12px; }
.tabs .tabrow::-webkit-scrollbar { display: none; }
.tab { flex: none; background: none; border: 0; padding: 14px 12px 12px; cursor: pointer; border-bottom: 2px solid transparent; display: grid; gap: 2px; text-align: left; }
.tab .a { font: 600 15px/1.2 var(--f-thai); }
.tab .b { font: 500 11px/1 var(--f-ui); color: var(--muted); letter-spacing: .06em; text-transform: uppercase; }
.tab[aria-selected="true"] { border-bottom-color: var(--lacquer); }
.tab[aria-selected="true"] .a { color: var(--lacquer); }

.pane { padding-block: 32px 120px; }
.block + .block { margin-top: 40px; }
.block > h2 { font: 400 26px/1.2 var(--f-display); display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.block > h2 small { font: 500 15px/1 var(--f-thai); color: var(--gold); }
.block > .hint { font: 400 14px/1.5 var(--f-ui); color: var(--muted); margin-top: 6px; }
.prose { margin-top: 14px; max-width: var(--measure); }

.toolbar { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-top: 14px; }
.switch { display: inline-flex; align-items: center; gap: 10px; font: 500 14px/1 var(--f-ui); cursor: pointer; user-select: none; }
.switch input { appearance: none; width: 38px; height: 22px; border-radius: 999px; background: var(--rule); position: relative; cursor: pointer; transition: background .15s; margin: 0; }
.switch input::after { content: ""; position: absolute; top: 3px; left: 3px; width: 16px; height: 16px; border-radius: 50%; background: var(--sheet); transition: transform .15s; box-shadow: 0 1px 2px rgb(0 0 0 / .2); }
.switch input:checked { background: var(--lacquer); }
.switch input:checked::after { transform: translateX(16px); }

.para { margin-top: 26px; max-width: var(--measure); }
.para .pl { font: 600 13px/1 var(--f-thai); color: var(--gold); letter-spacing: .02em; }
.para .pt { font: 400 21px/2.05 var(--f-thai); margin-top: 8px; text-indent: 2em; }
.para .pe { font: italic 400 16px/1.6 var(--f-body); color: var(--muted); margin-top: 8px; padding-left: 14px; border-left: 2px solid var(--rule); }

.glossbar {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 25;
  padding-bottom: env(safe-area-inset-bottom, 0px);
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
  pointer-events: none;
}
.glossbar .card {
  pointer-events: auto; max-width: 640px; margin: 0 auto 14px; background: var(--ink); color: var(--sheet);
  border-radius: 14px; padding: 14px 16px; box-shadow: 0 12px 40px rgb(0 0 0 / .3);
  display: grid; grid-template-columns: 1fr auto; gap: 2px 12px;
}
.glossbar .w { font: 700 22px/1.35 var(--f-thai); color: var(--hero-gold); }
.glossbar .m { font: 600 15px/1.4 var(--f-ui); }
.glossbar .n { font: 400 14px/1.5 var(--f-body); opacity: .82; grid-column: 1 / -1; }
.glossbar .x { grid-row: 1 / span 2; grid-column: 2; align-self: start; background: none; border: 0; color: inherit; opacity: .7; cursor: pointer; font: 400 24px/1 var(--f-mono); padding: 2px 4px; }
.glossbar .go { grid-column: 1 / -1; margin-top: 6px; justify-self: start; color: var(--hero-gold); }

.quotes { margin-top: 14px; display: grid; gap: 12px; max-width: var(--measure); }
.quotes blockquote { margin: 0; padding: 4px 0 4px 18px; border-left: 3px solid var(--lacquer); }
.quotes .q { font: 400 19px/1.8 var(--f-thai); }
.quotes .e { font: italic 400 15px/1.5 var(--f-body); color: var(--muted); }

.kp { margin: 14px 0 0; padding: 0; list-style: none; counter-reset: kp; display: grid; gap: 14px; max-width: var(--measure); }
.kp li { counter-increment: kp; display: grid; grid-template-columns: 32px 1fr; gap: 0 8px; }
.kp li::before { content: counter(kp); font: 500 14px/1.9 var(--f-mono); color: var(--gold); grid-row: span 2; }
.kp .t { font: 400 18px/1.8 var(--f-thai); }
.kp .e { font: italic 400 15px/1.5 var(--f-body); color: var(--muted); }

/* breakdown */
.bd { margin-top: 18px; display: grid; gap: 18px; }
.bdc { border: 1px solid var(--rule); border-radius: 12px; overflow: hidden; background: var(--sheet); }
.bdc .hd { padding: 16px 18px 14px; background: var(--paper); display: grid; grid-template-columns: auto 1fr; gap: 4px 12px; }
.bdc .num { font: 500 14px/1.9 var(--f-mono); color: var(--lacquer); grid-row: span 2; }
.bdc .s { font: 600 19px/1.85 var(--f-thai); min-width: 0; }
.bdc .e { font: italic 400 15px/1.5 var(--f-body); color: var(--muted); }
.tblwrap { overflow-x: auto; }
.bdc table { width: 100%; border-collapse: collapse; font: 400 14.5px/1.5 var(--f-ui); min-width: 480px; }
.bdc th { text-align: left; font: 600 11px/1 var(--f-ui); text-transform: uppercase; letter-spacing: .08em; color: var(--muted); padding: 10px 14px; border-bottom: 1px solid var(--rule); }
.bdc td { padding: 9px 14px; border-bottom: 1px solid var(--rule); vertical-align: top; }
.bdc tr:last-child td { border-bottom: 0; }
.bdc td.w { font: 600 17px/1.5 var(--f-thai); white-space: nowrap; color: var(--ink); }
.bdc td.n { color: var(--muted); font-family: var(--f-body); }
.bdc tr.hl td { background: var(--gold-wash); }
.collapse { margin-top: 10px; }
@media (max-width: 600px) {
  .bdc table { min-width: 0; }
  .bdc thead { display: none; }
  .bdc tbody, .bdc tr, .bdc td { display: block; }
  .bdc tr { display: grid; grid-template-columns: minmax(0, auto) minmax(0, 1fr); gap: 2px 12px; padding: 10px 16px; border-bottom: 1px solid var(--rule); }
  .bdc tr:last-child { border-bottom: 0; }
  .bdc td { padding: 0; border: 0; }
  .bdc td.w { white-space: normal; }
  .bdc td.n { grid-column: 1 / -1; font-size: 14px; }
  .bdc td.n:empty { display: none; }
}

/* vocab */
.vgrid { margin-top: 18px; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
@media (max-width: 760px) { .vgrid { grid-template-columns: 1fr; } }
.vc { border: 1px solid var(--rule); border-radius: 12px; padding: 18px; display: grid; gap: 10px; align-content: start; min-width: 0; }
.vc .top { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.vc .w { font: 700 24px/1.4 var(--f-thai); color: var(--lacquer); }
.vc .pos { font: 500 12px/1 var(--f-mono); color: var(--muted); }
.vc .g { font: 600 15px/1.4 var(--f-ui); }
.vc .def { font: 400 16px/1.75 var(--f-thai); padding: 10px 12px; background: var(--paper); border-radius: 8px; }
.vc .def i { display: block; font: italic 400 14.5px/1.5 var(--f-body); color: var(--muted); margin-top: 2px; }
.vc .ex { display: grid; gap: 8px; }
.vc .ex div { font: 400 16px/1.75 var(--f-thai); }
.vc .ex i { display: block; font: italic 400 14.5px/1.5 var(--f-body); color: var(--muted); }
.vc .note { font: 400 14px/1.5 var(--f-ui); color: var(--muted); border-top: 1px dashed var(--rule); padding-top: 10px; }
.vc .note b { color: var(--gold); font-weight: 600; }
.vc.hidden-def .g, .vc.hidden-def .def, .vc.hidden-def .ex, .vc.hidden-def .note { filter: blur(6px); user-select: none; }
.vc.hidden-def { cursor: pointer; }

/* grammar */
.gram { margin-top: 18px; display: grid; gap: 18px; }
.gb { border: 1px solid var(--rule); border-radius: 12px; overflow: hidden; }
.gb .h { padding: 14px 18px; background: var(--paper); display: flex; gap: 12px; align-items: baseline; }
.gb .h .k { font: 500 14px/1 var(--f-mono); color: var(--gold); }
.gb .h h3 { font: 600 18px/1.5 var(--f-thai); }
.gb .b { padding: 16px 18px 18px; display: grid; gap: 14px; }
.gb .exp { font: 400 16.5px/1.8 var(--f-thai); }
.gb .exp i { display: block; font: italic 400 15px/1.55 var(--f-body); color: var(--muted); margin-top: 4px; }
.gb .formula { font: 500 15.5px/1.7 var(--f-thai); background: var(--gold-wash); border-radius: 8px; padding: 10px 14px; overflow-x: auto; }
.gb .formula span { font: 600 11px/1 var(--f-ui); letter-spacing: .1em; text-transform: uppercase; color: var(--gold); display: block; margin-bottom: 4px; }
.gb ol { margin: 0; padding-left: 20px; display: grid; gap: 8px; }
.gb li { font: 400 16.5px/1.75 var(--f-thai); }
.gb li i { display: block; font: italic 400 14.5px/1.5 var(--f-body); color: var(--muted); }
.gb .watch { font: 400 14.5px/1.55 var(--f-ui); border-left: 3px solid var(--lacquer); padding: 4px 0 4px 12px; }
.gb .watch b { color: var(--lacquer); }

/* questions */
.qs { margin: 16px 0 0; padding: 0; list-style: none; display: grid; gap: 16px; max-width: var(--measure); }
.qi { border: 1px solid var(--rule); border-radius: 12px; padding: 16px 18px; display: grid; gap: 8px; }
.qi .q { font: 600 18px/1.75 var(--f-thai); display: grid; grid-template-columns: 28px 1fr; }
.qi .q span { font: 500 14px/2.2 var(--f-mono); color: var(--gold); }
.qi .qe { font: italic 400 15px/1.5 var(--f-body); color: var(--muted); padding-left: 28px; }
.qi .ans { margin-left: 28px; padding: 12px 14px; background: var(--ok-wash); border-radius: 8px; font: 400 17px/1.8 var(--f-thai); }
.qi .ans i { display: block; font: italic 400 14.5px/1.5 var(--f-body); color: var(--muted); margin-top: 4px; }
.qi textarea { margin-left: 28px; width: calc(100% - 28px); min-height: 70px; resize: vertical; font: 400 17px/1.7 var(--f-thai); padding: 10px 12px; border-radius: 8px; border: 1px solid var(--rule); background: var(--paper); color: var(--ink); }
.qi .actions { margin-left: 28px; }
.opts { margin-left: 28px; display: grid; gap: 8px; }
.opt { text-align: left; display: grid; grid-template-columns: 26px 1fr; gap: 8px; align-items: baseline; padding: 10px 12px; border: 1px solid var(--rule); border-radius: 10px; background: var(--sheet); cursor: pointer; font: 400 17px/1.6 var(--f-thai); }
.opt span { font: 600 15px/1 var(--f-thai); color: var(--muted); }
.opt:hover { border-color: var(--gold); }
.opt.right { border-color: var(--ok); background: var(--ok-wash); }
.opt.wrong { border-color: var(--bad); background: var(--bad-wash); }
.why { margin-left: 28px; font: 400 15px/1.55 var(--f-ui); }
.why b.ok { color: var(--ok); } .why b.no { color: var(--bad); }

.donebar { margin-top: 36px; display: flex; flex-wrap: wrap; gap: 12px; align-items: center; padding: 18px; border-radius: 12px; background: var(--paper); }
.donebar p { font: 400 15px/1.5 var(--f-ui); color: var(--muted); flex: 1 1 260px; }

/* locked lesson */
.locked { margin-top: 26px; border: 1px dashed var(--gold); border-radius: 14px; padding: 26px; background: var(--gold-wash); display: grid; gap: 12px; max-width: var(--measure); }
.locked h3 { font: 400 24px/1.2 var(--f-display); }

/* ── Sheet (paywall / sign-in) ── */
.scrim { position: fixed; inset: 0; z-index: 40; background: rgb(10 8 10 / .55); display: flex; align-items: center; justify-content: center; padding: 16px; }
.sheet {
  background: var(--sheet); color: var(--ink); border-radius: 18px; width: min(520px, 100%); max-height: calc(100% - 32px); overflow: auto;
  padding: 26px 24px 24px; box-shadow: 0 20px 60px rgb(0 0 0 / .35); display: grid; gap: 16px; position: relative;
}
@media (max-width: 560px) {
  .scrim { align-items: flex-end; padding: 0; }
  .sheet { border-radius: 18px 18px 0 0; width: 100%; padding-bottom: calc(24px + env(safe-area-inset-bottom, 0px)); }
}
.sheet .close { position: absolute; top: 10px; right: 10px; background: none; border: 0; font: 400 26px/1 var(--f-mono); color: var(--muted); cursor: pointer; padding: 6px 10px; }
.sheet h2 { font: 400 28px/1.15 var(--f-display); padding-right: 30px; }
.sheet .lead { color: var(--muted); font: 400 15px/1.5 var(--f-ui); }
.choice { display: grid; gap: 10px; }
.choice label { display: grid; grid-template-columns: 22px 1fr auto; gap: 10px; align-items: center; padding: 14px 16px; border: 1px solid var(--rule); border-radius: 12px; cursor: pointer; }
.choice label:has(input:checked) { border: 2px solid var(--lacquer); padding: 13px 15px; }
.choice input { accent-color: var(--lacquer); width: 18px; height: 18px; margin: 0; }
.choice .nm { font: 600 16px/1.3 var(--f-ui); }
.choice .nm small { display: block; font: 400 13px/1.4 var(--f-ui); color: var(--muted); }
.choice .pr { font: 400 22px/1 var(--f-display); text-align: right; }
.choice .pr small { display: block; font: 400 12px/1.4 var(--f-ui); color: var(--muted); }
.field { display: grid; gap: 6px; }
.field label { font: 600 14px/1 var(--f-ui); }
.field input { font: 400 17px/1.4 var(--f-ui); padding: 12px 14px; border-radius: 10px; border: 1px solid var(--rule); background: var(--paper); color: var(--ink); width: 100%; }
.field input.code { font: 500 26px/1 var(--f-mono); letter-spacing: .4em; text-align: center; }
.msg { font: 400 14px/1.5 var(--f-ui); padding: 10px 12px; border-radius: 10px; background: var(--paper); color: var(--muted); }
.msg.err { background: var(--bad-wash); color: var(--bad); }
.msg.ok { background: var(--ok-wash); color: var(--ok); }
.legal { font: 400 12.5px/1.5 var(--f-ui); color: var(--muted); }

/* account */
.acct { padding-block: 40px 80px; display: grid; gap: 22px; max-width: 640px; }
.acct h1 { font: 400 34px/1.15 var(--f-display); }
.panel { border: 1px solid var(--rule); border-radius: 14px; padding: 20px; background: var(--sheet); display: grid; gap: 10px; }
.panel dl { margin: 0; display: grid; grid-template-columns: max-content 1fr; gap: 6px 16px; font: 400 15px/1.5 var(--f-ui); }
.panel dt { color: var(--muted); }
.panel dd { margin: 0; overflow-wrap: anywhere; }
.status { display: inline-block; font: 600 12px/1 var(--f-ui); padding: 6px 9px; border-radius: 999px; }
.status.on { background: var(--ok-wash); color: var(--ok); }
.status.off { background: var(--paper); color: var(--muted); }

.toast { position: fixed; left: 50%; bottom: calc(24px + env(safe-area-inset-bottom, 0px)); transform: translateX(-50%); z-index: 50; background: var(--ink); color: var(--sheet); font: 500 14px/1.4 var(--f-ui); padding: 12px 16px; border-radius: 10px; box-shadow: var(--shadow); max-width: calc(100% - 32px); }

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