/* ── tokens ─────────────────────────────────────────────────────────── */
:root{
  --ink:#16181d; --ink-2:#454a55; --muted:#6b7280;
  --bg:#fbfaf8; --surface:#fff; --line:#e6e3dd; --line-2:#efece6;
  --radius:14px; --radius-lg:22px;
  --shadow:0 1px 2px rgba(16,18,29,.05),0 8px 24px -12px rgba(16,18,29,.18);
  --shadow-lg:0 2px 4px rgba(16,18,29,.06),0 24px 48px -20px rgba(16,18,29,.28);
  --wrap:1120px;
  --sans:ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  --serif:"Iowan Old Style","Palatino Linotype",Palatino,Georgia,serif;
  --mono:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
}
@media (prefers-color-scheme:dark){
  :root{
    --ink:#f2f0ec; --ink-2:#c3c7d1; --muted:#98a0ae;
    --bg:#111318; --surface:#191c22; --line:#2a2e37; --line-2:#232730;
    --shadow:0 1px 2px rgba(0,0,0,.4),0 8px 24px -12px rgba(0,0,0,.6);
    --shadow-lg:0 2px 4px rgba(0,0,0,.5),0 24px 48px -20px rgba(0,0,0,.75);
  }
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--sans);
  font-size:17px;line-height:1.65;-webkit-font-smoothing:antialiased}
img{max-width:100%;height:auto}
a{color:inherit}
h1,h2,h3{line-height:1.18;letter-spacing:-.02em;margin:0 0 .4em}
h1{font-size:clamp(2rem,1.3rem + 2.4vw,3.1rem);font-weight:800}
h2{font-size:clamp(1.35rem,1.1rem + .9vw,1.85rem);font-weight:750}
h3{font-size:1.06rem;font-weight:700}
p{margin:0 0 1em}
.wrap{max-width:var(--wrap);margin:0 auto;padding:0 20px}
.section{padding:clamp(28px,4vw,52px) 20px}
.narrow{max-width:760px}
.muted{color:var(--muted)}
.small{font-size:.87rem}
.mono{font-family:var(--mono);font-size:.95em}
.sr,.skip{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}
.skip:focus{position:fixed;top:8px;left:8px;width:auto;height:auto;clip:auto;
  background:var(--brand);color:#fff;padding:10px 16px;border-radius:8px;z-index:99}

/* ── header ─────────────────────────────────────────────────────────── */
.site-header{position:sticky;top:0;z-index:40;background:color-mix(in srgb,var(--bg) 88%,transparent);
  backdrop-filter:saturate(1.6) blur(12px);border-bottom:1px solid var(--line)}
.header-inner{display:flex;align-items:center;gap:18px;min-height:64px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;font-weight:800;letter-spacing:-.02em}
.brand-mark{font-size:1.5rem;line-height:1}
.brand-text{display:flex;flex-direction:column;line-height:1.15}
.brand-text i{font-style:normal;font-size:.72rem;font-weight:500;color:var(--muted)}
.nav{margin-left:auto;display:flex;align-items:center;gap:6px;flex-wrap:wrap}
.nav a{text-decoration:none;font-size:.93rem;font-weight:600;color:var(--ink-2);
  padding:7px 11px;border-radius:9px}
.nav a:hover{background:var(--line-2);color:var(--ink)}
.nav a[aria-current]{color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,transparent)}
.nav .nav-cta{background:var(--brand);color:#fff;padding:8px 15px;box-shadow:var(--shadow)}
.nav .nav-cta:hover{background:var(--brand-dark);color:#fff}
.nav-toggle{display:none;margin-left:auto;width:42px;height:38px;border:1px solid var(--line);
  background:var(--surface);border-radius:10px;cursor:pointer;position:relative}
.nav-toggle span,.nav-toggle span::before,.nav-toggle span::after{position:absolute;left:11px;width:18px;
  height:2px;background:var(--ink);border-radius:2px;content:"";transition:.18s}
.nav-toggle span{top:18px}
.nav-toggle span::before{top:-6px;left:0}
.nav-toggle span::after{top:6px;left:0}
@media (max-width:900px){
  .nav-toggle{display:block}
  .nav{position:absolute;top:100%;left:0;right:0;flex-direction:column;align-items:stretch;
    background:var(--surface);border-bottom:1px solid var(--line);padding:10px;gap:2px;display:none;
    box-shadow:var(--shadow)}
  .nav.open{display:flex}
  .nav a{padding:11px 13px}
}

/* ── hero ───────────────────────────────────────────────────────────── */
.hero{padding:clamp(34px,5vw,72px) 0 clamp(20px,3vw,36px);
  background:linear-gradient(180deg,color-mix(in srgb,var(--brand) 9%,transparent),transparent 78%)}
.hero-grid{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,.85fr);gap:44px;align-items:center}
.eyebrow{font-size:1.15rem;color:var(--brand);font-weight:700;margin:0 0 .3em;letter-spacing:.01em}
.lede{font-size:1.12rem;color:var(--ink-2);max-width:56ch}
.hero-cta{display:flex;flex-wrap:wrap;gap:12px;margin:22px 0 26px}
.hero-stats{list-style:none;display:flex;flex-wrap:wrap;gap:26px;padding:22px 0 0;margin:0;
  border-top:1px solid var(--line)}
.hero-stats li{display:flex;flex-direction:column}
.hero-stats b{font-size:1.55rem;font-weight:800;letter-spacing:-.03em}
.hero-stats span{font-size:.82rem;color:var(--muted);text-transform:lowercase}
.hero-art{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
.hero-glyph{display:grid;place-items:center;aspect-ratio:1;background:var(--surface);
  border:1px solid var(--line);border-radius:var(--radius);font-size:clamp(1.6rem,4vw,2.4rem);
  box-shadow:var(--shadow);color:var(--ink)}
.hero-art span:nth-child(3n+2){background:color-mix(in srgb,var(--brand) 8%,var(--surface))}
@media (max-width:860px){.hero-grid{grid-template-columns:1fr;gap:28px}.hero-art{max-width:340px}}

/* ── buttons ────────────────────────────────────────────────────────── */
.btn{display:inline-flex;align-items:center;gap:8px;text-decoration:none;font-weight:650;
  font-size:.97rem;padding:12px 20px;border-radius:11px;border:1px solid transparent;cursor:pointer;
  transition:transform .12s ease,box-shadow .12s ease,background .12s ease;font-family:inherit}
.btn:active{transform:translateY(1px)}
.btn.primary{background:var(--brand);color:#fff;box-shadow:var(--shadow)}
.btn.primary:hover{background:var(--brand-dark);box-shadow:var(--shadow-lg)}
.btn.ghost{background:var(--surface);border-color:var(--line);color:var(--ink)}
.btn.ghost:hover{border-color:var(--brand);color:var(--brand)}
.btn.dark{background:var(--ink);color:var(--bg)}
.btn.small{padding:8px 14px;font-size:.88rem}
.btn-row{display:flex;flex-wrap:wrap;gap:10px;align-items:center}
.pill{display:inline-block;padding:7px 13px;border-radius:999px;background:var(--line-2);
  font-size:.85rem}

/* ── generic sections ───────────────────────────────────────────────── */
.section-head{display:flex;align-items:baseline;justify-content:space-between;gap:16px;flex-wrap:wrap}
.more{color:var(--brand);text-decoration:none;font-weight:650;font-size:.92rem;white-space:nowrap}
.more:hover{text-decoration:underline}
.count{display:inline-block;font-size:.72em;font-weight:700;color:var(--brand);
  background:color-mix(in srgb,var(--brand) 12%,transparent);padding:2px 9px;border-radius:999px;
  vertical-align:middle}
.count.big{font-size:.45em;vertical-align:middle}
.intro{font-size:1.08rem;color:var(--ink-2);max-width:72ch;border-left:3px solid var(--brand);
  padding-left:20px}
.page-head{padding:clamp(26px,3.5vw,44px) 20px 6px}
.crumbs{padding-top:16px;font-size:.86rem;color:var(--muted)}
.crumbs a{color:var(--muted);text-decoration:none}
.crumbs a:hover{color:var(--brand)}
.crumbs span{margin:0 6px;opacity:.6}
.crumbs b{color:var(--ink)}
.prose h2{margin-top:1.7em}

/* ── chart ──────────────────────────────────────────────────────────── */
.chart-tools{display:flex;flex-wrap:wrap;gap:12px;align-items:center;margin:22px 0 4px}
.chart-tools input{flex:1 1 260px;max-width:380px;padding:11px 15px;border-radius:11px;
  border:1px solid var(--line);background:var(--surface);color:var(--ink);font:inherit;font-size:.95rem}
.chart-tools input:focus{outline:2px solid color-mix(in srgb,var(--brand) 45%,transparent);
  outline-offset:1px;border-color:var(--brand)}
.chips{display:flex;gap:8px;flex-wrap:wrap}
.chip{padding:8px 14px;border-radius:999px;border:1px solid var(--line);background:var(--surface);
  color:var(--ink-2);font:inherit;font-size:.88rem;font-weight:600;cursor:pointer}
.chip.active{background:var(--brand);border-color:var(--brand);color:#fff}

.sub-head{margin:26px 0 0;font-size:1.02rem;font-weight:700;color:var(--ink-2)}
.chart-grid{display:grid;gap:12px;margin-top:18px;
  grid-template-columns:repeat(auto-fill,minmax(122px,1fr))}
.chart-grid.compact{grid-template-columns:repeat(auto-fill,minmax(104px,1fr));gap:9px}
.chart-cell{position:relative;display:flex;flex-direction:column;align-items:center;gap:2px;
  padding:16px 10px 13px;background:var(--surface);border:1px solid var(--line);
  border-radius:var(--radius);text-decoration:none;color:inherit;
  transition:transform .13s ease,box-shadow .13s ease,border-color .13s ease}
.chart-cell:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg);border-color:var(--brand)}
.chart-cell b{font-size:2.35rem;line-height:1.25;font-weight:500}
.compact .chart-cell b{font-size:1.95rem}
.cell-name{font-size:.83rem;font-weight:650;text-align:center}
.cell-sound{font-family:var(--mono);font-size:.76rem;color:var(--muted)}
.cell-play{position:absolute;top:7px;right:8px;font-size:.62rem;color:var(--muted);opacity:0;
  transition:opacity .13s;line-height:1;padding:4px;border-radius:50%}
.chart-cell:hover .cell-play{opacity:1}
.cell-play:hover{color:var(--brand)}
.chart-cell.playing{border-color:var(--brand);
  box-shadow:0 0 0 3px color-mix(in srgb,var(--brand) 22%,transparent)}

/* ── group cards ────────────────────────────────────────────────────── */
.group-cards{display:grid;gap:16px;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));margin-top:18px}
.group-card{display:block;padding:20px;background:var(--surface);border:1px solid var(--line);
  border-radius:var(--radius-lg);text-decoration:none;color:inherit;transition:transform .14s,box-shadow .14s}
.group-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg)}
.group-preview{display:flex;gap:8px;margin-bottom:14px;font-size:1.6rem;color:var(--brand);opacity:.9}
.group-card p{margin:0;color:var(--muted);font-size:.92rem}

/* ── letter list ────────────────────────────────────────────────────── */
.letter-list{list-style:none;padding:0;margin:18px 0 0;display:grid;gap:8px}
.letter-list a{display:grid;grid-template-columns:56px 1fr auto;align-items:center;gap:14px;
  padding:11px 16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  text-decoration:none;color:inherit}
.letter-list a:hover{border-color:var(--brand)}
.letter-list b{font-size:1.8rem;font-weight:500;text-align:center}
.ll-name{font-weight:650}
.ll-gloss{color:var(--muted);font-size:.9rem;margin-left:8px}
.ll-sound{color:var(--brand);margin-left:8px;font-size:.86rem}
.ll-meta{color:var(--muted);font-size:.8rem;white-space:nowrap}
@media (max-width:640px){.letter-list a{grid-template-columns:44px 1fr}.ll-meta{display:none}}

/* ── letter page ────────────────────────────────────────────────────── */
.letter-hero{display:grid;grid-template-columns:minmax(0,300px) minmax(0,1fr);gap:36px;
  align-items:center;padding:22px 20px clamp(18px,3vw,32px)}
.letter-card{display:grid;place-items:center;gap:10px;padding:30px 20px;border-radius:var(--radius-lg);
  background:linear-gradient(160deg,color-mix(in srgb,var(--brand) 13%,var(--surface)),var(--surface));
  border:1px solid var(--line);box-shadow:var(--shadow)}
.glyph.big{font-size:clamp(6rem,16vw,9.5rem);line-height:1.05;font-weight:500}
.letter-pos{margin:0;font-size:.82rem;color:var(--muted);text-transform:uppercase;letter-spacing:.07em}
.letter-meta h1{margin-bottom:.15em}
.gloss{font-family:var(--serif);font-size:1.3rem;color:var(--ink-2);margin:0 0 .6rem}
.letter-meta h1 .native{font-weight:500;color:var(--muted);font-size:.72em;margin-left:.35em}
.letter-note{color:var(--ink-2);max-width:62ch;margin:0 0 1rem}
.facts{display:flex;flex-wrap:wrap;gap:10px 34px;margin:0 0 22px;padding:16px 0;
  border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.facts div{display:flex;flex-direction:column;gap:2px}
.facts dt{font-size:.74rem;text-transform:uppercase;letter-spacing:.07em;color:var(--muted)}
.facts dd{margin:0;font-weight:650;font-size:1.05rem}
@media (max-width:800px){.letter-hero{grid-template-columns:1fr;gap:22px}}

.audio-btn{display:inline-flex;align-items:center;gap:9px;padding:12px 20px;border-radius:11px;
  border:1px solid transparent;font:inherit;font-weight:650;font-size:.97rem;cursor:pointer;
  background:var(--brand);color:#fff;box-shadow:var(--shadow)}
.audio-btn.ghost{background:var(--surface);border-color:var(--line);color:var(--ink)}
.audio-btn .ico{font-size:.72em}
.audio-btn.playing{animation:pulse .55s ease}
@keyframes pulse{50%{transform:scale(1.04)}}

/* stroke order */
.stroke-block{display:grid;grid-template-columns:minmax(0,340px) minmax(0,1fr);gap:32px;
  align-items:center;margin-top:18px}
.stroke-stage{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius-lg);
  padding:14px;box-shadow:var(--shadow)}
.stroke-svg,.stroke-gif{display:block;width:100%;aspect-ratio:1;border-radius:12px;background:#fff}
@media (prefers-color-scheme:dark){.stroke-svg,.stroke-gif{background:#f7f7f5}}
.stroke-svg .guide line{stroke:#d9d9d9;stroke-width:.5;stroke-dasharray:3 3}
.stroke-svg .ghost-strokes path{fill:none;stroke:#e2e2df;stroke-width:6.5;stroke-linecap:round;
  stroke-linejoin:round}
.stroke-svg .live-strokes path{fill:none;stroke:var(--brand);stroke-width:6.5;stroke-linecap:round;
  stroke-linejoin:round;stroke-dasharray:var(--len);stroke-dashoffset:var(--len);
  animation:draw .85s ease forwards;animation-delay:calc(var(--i) * .75s)}
.stroke-svg.replay .live-strokes path{animation:none;stroke-dashoffset:var(--len)}
@keyframes draw{to{stroke-dashoffset:0}}
.stroke-svg .numbers text{font-family:var(--sans);font-size:7px;font-weight:800;fill:var(--brand);
  text-anchor:middle;paint-order:stroke;stroke:#fff;stroke-width:2.6px}
@media (prefers-reduced-motion:reduce){.stroke-svg .live-strokes path{animation:none;stroke-dashoffset:0}}
@media (max-width:800px){.stroke-block{grid-template-columns:1fr}}

/* font variants */
.font-strip{display:grid;gap:12px;grid-template-columns:repeat(auto-fit,minmax(130px,1fr));margin-top:16px}
.font-strip figure{margin:0;padding:18px 12px;text-align:center;background:var(--surface);
  border:1px solid var(--line);border-radius:var(--radius)}
.font-strip b{display:block;font-size:3rem;font-weight:400;line-height:1.3}
.font-strip figcaption{font-size:.8rem;color:var(--muted);margin-top:6px}

/* words table */
.words-table{width:100%;border-collapse:collapse;margin-top:14px;font-size:.98rem}
.words-table th{text-align:left;font-size:.75rem;text-transform:uppercase;letter-spacing:.07em;
  color:var(--muted);font-weight:700;padding:0 12px 8px;border-bottom:1px solid var(--line)}
.words-table td{padding:11px 12px;border-bottom:1px solid var(--line-2);vertical-align:middle}
.words-table tr:hover td{background:var(--surface)}
.words-table .word{font-size:1.28rem;font-weight:500;white-space:nowrap}
.words-table .mono{color:var(--brand);white-space:nowrap}
.words-table .tight{width:44px;text-align:right}
.icon-btn{width:32px;height:32px;border-radius:50%;border:1px solid var(--line);background:var(--surface);
  color:var(--ink-2);cursor:pointer;font-size:.65rem;line-height:1;display:inline-grid;place-items:center}
.icon-btn:hover{border-color:var(--brand);color:var(--brand)}
.icon-btn.playing{background:var(--brand);border-color:var(--brand);color:#fff}

/* prev / next */
.letter-nav{display:flex;justify-content:space-between;gap:14px;padding:8px 20px}
.np{display:flex;align-items:center;gap:10px;text-decoration:none;color:inherit;padding:12px 18px;
  background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);font-weight:600;
  font-size:.92rem}
.np:hover{border-color:var(--brand)}
.np span{font-size:.72rem;color:var(--muted);text-transform:uppercase;letter-spacing:.06em}
.np b{font-size:1.5rem;font-weight:500}
.np.next{margin-left:auto;text-align:right}
.np.next span{order:-1}

/* ── feature band ───────────────────────────────────────────────────── */
.feature-band{background:var(--surface);border-block:1px solid var(--line);
  padding:clamp(34px,4.5vw,58px) 0;margin-top:14px}
.features{display:grid;gap:22px;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));margin:26px 0 8px}
.feature h3{margin:.5em 0 .3em}
.feature p{color:var(--muted);font-size:.93rem;margin:0}
.fico{font-size:1.7rem}
.band-cta{margin-top:26px}
.band-inline{text-align:center;background:var(--surface);border:1px solid var(--line);
  border-radius:var(--radius-lg);margin:clamp(28px,4vw,52px) auto;max-width:calc(var(--wrap) - 40px)}
.band-inline p{max-width:60ch;margin-inline:auto}

/* tones */
.tone-strip{display:flex;gap:12px;flex-wrap:wrap;margin-top:16px}
.tone-chip{display:flex;align-items:center;gap:10px;padding:12px 18px;background:var(--surface);
  border:1px solid var(--line);border-radius:999px;text-decoration:none;color:inherit;font-size:.9rem;
  font-weight:600}
.tone-chip:hover{border-color:var(--brand)}
.tone-chip b{font-size:1.5rem;font-weight:500;color:var(--brand)}
.tone-grid{display:grid;gap:16px;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));margin-top:18px}
.tone-card{padding:22px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius-lg)}
.tone-card h2{font-size:1.1rem;margin:.4em 0 .2em}
.tone-card p{font-size:.92rem;color:var(--muted);margin:0 0 .5em}
.tone-mark{font-size:3rem;color:var(--brand);line-height:1}
.tone-native{font-size:1.1rem;color:var(--ink)!important}
.tone-example b{font-size:1.3rem}

/* faq */
.faq details{border:1px solid var(--line);border-radius:var(--radius);background:var(--surface);
  padding:2px 18px;margin-bottom:10px}
.faq summary{cursor:pointer;font-weight:650;padding:14px 0;list-style:none}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";float:right;color:var(--brand);font-weight:700;font-size:1.2rem;line-height:1}
.faq details[open] summary::after{content:"−"}
.faq p{color:var(--ink-2);margin:0 0 14px;max-width:78ch}

/* app band */
.app-band-inner{display:flex;flex-wrap:wrap;gap:20px;align-items:center;justify-content:space-between;
  padding:26px 28px;border-radius:var(--radius-lg);
  background:linear-gradient(120deg,color-mix(in srgb,var(--brand) 14%,var(--surface)),var(--surface));
  border:1px solid var(--line)}
.app-band-inner h2{margin-bottom:.2em}
.store-links{display:flex;gap:10px;flex-wrap:wrap}

/* ── footer ─────────────────────────────────────────────────────────── */
.site-footer{margin-top:auto;border-top:1px solid var(--line);background:var(--surface);
  padding:40px 0 26px}
.footer-grid{display:grid;gap:26px;grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}
.footer-grid h3{font-size:.78rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);
  margin-bottom:.8em}
.footer-grid a{display:block;text-decoration:none;color:var(--ink-2);font-size:.93rem;padding:3px 0}
.footer-grid a:hover{color:var(--brand)}
.foot-brand{font-weight:750;margin:0 0 .4em}
.foot-legal{margin-top:28px;padding-top:18px;border-top:1px solid var(--line-2)}
.foot-legal p{margin:0;font-size:.84rem}
.word-block .section-head h2 a{text-decoration:none}
.glyph.inline{font-size:1.4rem;font-weight:500;margin-right:6px}
/* 窄屏上例词表 4 列会撑破视口(整页横向滚动),让表格自己滚 */
.table-wrap{overflow-x:auto;-webkit-overflow-scrolling:touch}
/* 兄弟站互链:一行内联,不占版面又能把 22 个站连成网 */
.other-sites{margin-top:26px;padding-top:18px;border-top:1px solid var(--line-2)}
.other-sites h3{font-size:.78rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);
  margin-bottom:.7em}
.other-sites p{margin:0;font-size:.88rem;line-height:2;color:var(--muted)}
.other-sites a{color:var(--ink-2);text-decoration:none}
.other-sites a:hover{color:var(--brand);text-decoration:underline}