:root{
  --en-ink:#1c1917; --en-ink2:#57534e; --en-ink3:#8a827c;
  --en-line:#e7e2db; --en-bg:#faf8f5; --en-card:#ffffff;
  --en-brand:#c2410c; --en-brand-soft:#fff4ec; --en-brand-line:#f6d3bd;
  --en-warn:#a16207; --en-warn-soft:#fef9e7;
  --ipa:"Charis SIL","Doulos SIL","Lucida Sans Unicode","Segoe UI",serif;
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
[hidden]{display:none!important}
html,body{margin:0;padding:0}
body{
  background:#f6f7f9; color:var(--en-ink);
  font:15px/1.62 -apple-system,"Segoe UI","Microsoft YaHei",system-ui,sans-serif;
  -webkit-font-smoothing:antialiased;
}
.phone{max-width:540px;margin:0 auto;background:var(--en-bg);min-height:calc(100vh - 54px);padding:0 0 40px}
@media(min-width:720px){.phone{border-left:1px solid #e7e2db;border-right:1px solid #e7e2db}}

/* 头部 */
.hd{padding:26px 20px 16px}
.hd .kicker{font-size:11.5px;letter-spacing:.06em;color:var(--en-brand);font-weight:600}
.hd h1{margin:6px 0 4px;font-size:23px;line-height:1.28;letter-spacing:-.01em}
.hd h1 small{display:block;font-size:14px;font-weight:400;color:var(--en-ink2);margin-top:5px;letter-spacing:0}
.hd .meta{margin-top:9px;font-size:12.5px;color:var(--en-ink3)}
.crumb{display:inline-flex;align-items:center;gap:5px;font-size:12.5px;color:var(--en-ink3);
  text-decoration:none;margin-bottom:2px}
.crumb:hover{color:var(--en-brand)}
.crumbs{display:flex;align-items:baseline;justify-content:space-between;gap:10px}
.crumbs .crumb{margin-bottom:0}
.promise{
  margin:14px 20px 0;padding:12px 14px;border-radius:12px;
  background:var(--en-brand-soft);border:1px solid var(--en-brand-line);
  font-size:13.5px;color:#8a3d0f;line-height:1.6;
}

/* tab */
.tabs{display:flex;gap:6px;margin:18px 20px 0;padding:4px;background:#f1ede7;border-radius:11px}
.tab{
  flex:1;border:0;background:transparent;color:var(--en-ink2);
  font:inherit;font-size:13.5px;padding:8px 0;border-radius:8px;cursor:pointer;font-weight:500;
}
.tab.on{background:#fff;color:var(--en-ink);font-weight:600;box-shadow:0 1px 3px rgba(0,0,0,.07)}

/* 卡片 */
.list{padding:16px 20px 0;display:flex;flex-direction:column;gap:14px}
.card{background:var(--en-card);border:1px solid var(--en-line);border-radius:16px;padding:16px 16px 14px}
.c-top{display:flex;align-items:flex-start;justify-content:space-between;gap:10px}
.c-idx{font-size:11px;color:var(--en-ink3);font-variant-numeric:tabular-nums;margin-bottom:2px}
.c-w{font-size:29px;font-weight:650;letter-spacing:-.02em;line-height:1.15}
.c-meta{margin-top:3px;display:flex;align-items:baseline;gap:7px;flex-wrap:wrap}
.c-ipa{font-family:var(--ipa);font-size:15.5px;color:var(--en-ink2)}
.c-pos{font-size:12px;color:var(--en-ink3);font-style:italic}
.c-cn{font-size:14px;color:var(--en-ink)}
.play{display:flex;gap:6px;flex-shrink:0;padding-top:4px}
.pbtn{
  border:1px solid var(--en-brand-line);background:var(--en-brand-soft);color:var(--en-brand);
  width:38px;height:38px;border-radius:10px;font-size:15px;cursor:pointer;
  display:flex;align-items:center;justify-content:center;padding:0;
}
.pbtn:active{transform:scale(.94)}
.pbtn.slow{width:auto;padding:0 10px;font-size:12px;gap:3px}

/* 切分块 */
.split{display:flex;flex-wrap:wrap;align-items:stretch;gap:6px;margin-top:14px}
.seg{
  border:1px solid var(--en-line);background:#fbfaf8;border-radius:9px;
  padding:6px 9px 5px;cursor:pointer;text-align:center;min-width:44px;
  display:flex;flex-direction:column;gap:1px;
}
.seg b{font-size:16px;font-weight:600;letter-spacing:.02em;line-height:1.2}
.seg i{font-family:var(--ipa);font-style:normal;font-size:12.5px;color:var(--en-ink2)}
.seg.key{background:var(--en-brand-soft);border-color:var(--en-brand-line)}
.seg.key i{color:var(--en-brand)}
.seg.mute{background:#fbf9f7;border-style:dashed;border-color:#ddd5cc}
.seg.mute b{color:#a8a19b}
.seg.mute i{color:#b8b0a8}
.seg.hit{background:#fdeee2;border-color:#e9b48c}
.split-note{font-size:11.5px;color:var(--en-ink3);margin-top:7px}
.split-hint{font-size:11px;color:var(--en-brand);margin-top:6px;letter-spacing:.02em}

/* 提示行 */
.trap{
  margin-top:12px;padding:9px 11px;border-radius:9px;
  background:var(--en-warn-soft);border:1px solid #f2e3b3;
  font-size:13px;color:#7c5209;line-height:1.55;
}
.trap b{font-weight:600}
.say{
  margin-top:8px;padding-left:10px;border-left:3px solid var(--en-brand-line);
  font-size:13px;color:var(--en-ink2);line-height:1.55;
}
.say b{color:var(--en-ink);font-weight:600}

/* 句型卡 */
.ph-tag{
  display:inline-block;margin-left:6px;padding:1px 7px 2px;border-radius:6px;
  background:var(--en-brand-soft);color:var(--en-brand);
  font-size:10.5px;font-weight:600;letter-spacing:.02em;vertical-align:1.5px;
}
.ph-en{font-size:20px;font-weight:650;line-height:1.35;letter-spacing:-.012em;margin-top:1px}
.ph-ipa{font-family:var(--ipa);font-size:14px;color:var(--en-ink2);margin-top:3px}
.ph-cn{font-size:14.5px;color:var(--en-ink2);margin-top:6px;line-height:1.55}
body.no-cn .ph-cn{display:none}
.ph-src{font-size:11.5px;color:var(--en-ink3);margin-top:5px;letter-spacing:.01em}

/* 中文释义开关：孩子自己念的时候可以先把中文藏起来 */
.cnbar{display:flex;align-items:center;justify-content:flex-end;gap:8px;margin:9px 20px -4px}
.cnbar .lb{font-size:11.5px;color:var(--en-ink3)}
.sw{width:34px;height:20px;border-radius:999px;border:1px solid var(--en-line);background:#e9e4dd;
  position:relative;padding:0;cursor:pointer;transition:background .15s,border-color .15s;flex:0 0 auto}
.sw::after{content:"";position:absolute;top:2px;left:2px;width:14px;height:14px;border-radius:50%;
  background:#fff;box-shadow:0 1px 2px rgba(0,0,0,.2);transition:transform .15s}
.sw.on{background:var(--en-brand);border-color:var(--en-brand)}
.sw.on::after{transform:translateX(14px)}
.ph-when{margin-top:11px;font-size:12.5px;color:var(--en-ink2);line-height:1.65}
.ph-when b{color:var(--en-ink);font-weight:600}

/* 44 音 */
.snd-wrap{padding:16px 20px 0}
.snd-lead{font-size:13.5px;color:var(--en-ink2);line-height:1.65;margin:0 0 6px}
.snd-lead b{color:var(--en-brand)}
.grp{margin-top:18px}.grp h3{
  font-size:12px;letter-spacing:.05em;color:var(--en-ink3);font-weight:600;
  margin:0 0 8px;display:flex;align-items:center;gap:7px;
}
.grp h3 span{font-weight:400;letter-spacing:0;font-size:11.5px}
.snd-note{
  margin:20px 0 0;padding:10px 12px;border-radius:10px;
  background:#f4f1ec;font-size:12px;color:var(--en-ink2);line-height:1.65;
}
.snd-note b{color:var(--en-ink)}
.grid{display:grid;grid-template-columns:repeat(4,1fr);gap:7px}
.snd{
  border:1px solid var(--en-line);background:#fff;border-radius:10px;
  padding:8px 4px 7px;text-align:center;cursor:pointer;
  display:flex;flex-direction:column;align-items:center;gap:2px;
}
.snd:active{background:var(--en-brand-soft)}
.snd .ipa{font-family:var(--ipa);font-size:16px;line-height:1.25}
.snd .ex{font-size:11px;color:var(--en-ink3);line-height:1.3;white-space:nowrap}
.snd.hit .ipa{color:var(--en-brand);font-weight:600}

/* 底部说明 */
.foot{margin:22px 20px 0;padding-top:14px;border-top:1px dashed var(--en-line);font-size:12px;color:var(--en-ink3);line-height:1.7}
.foot b{color:var(--en-ink2)}
.tag{display:inline-block;padding:1px 6px;border-radius:5px;background:#f1ede7;font-size:11px;color:var(--en-ink2)}

/* 单元列表 */
.ulist{margin-top:8px}
.ulist .lead{font-size:13.5px;color:var(--en-ink2);line-height:1.7;margin:12px 0 14px}
.unit{
  display:flex;align-items:center;gap:13px;text-decoration:none;color:inherit;
  background:#fff;border:1px solid var(--en-line);border-radius:14px;
  padding:14px 15px;margin-bottom:11px;
}
.unit.on:active{background:#fdfaf6}
.unit .no{
  flex-shrink:0;width:44px;height:44px;border-radius:12px;display:grid;place-items:center;
  background:var(--en-brand-soft);border:1px solid var(--en-brand-line);
  color:var(--en-brand);font-weight:700;font-size:12px;line-height:1.1;text-align:center;
}
.unit .no b{display:block;font-size:16px;letter-spacing:-.02em}
.unit .bd{min-width:0;flex:1}
.unit .t,.unit .d,.unit .k,.extra .t,.extra .d{display:block}
.unit .t{font-size:16.5px;font-weight:650;letter-spacing:-.01em}
.unit .d{font-size:12.5px;color:var(--en-ink3);margin-top:3px}
.unit .k{font-size:11.5px;color:var(--en-brand);margin-top:5px;letter-spacing:.01em}
.unit .go{flex-shrink:0;color:var(--en-ink3);font-size:18px}
/* 册列表：右上角那格里放「三上」「三下」，字号比单元号小一号 */
.unit .no.bk{font-size:15px;font-weight:700;letter-spacing:0}
.unit.off{opacity:.62}
.unit.off .no{background:#f4f1ec;border-color:#e7e2db;color:var(--en-ink3)}
.unit.off .k{color:var(--en-ink3)}
.extra{
  display:flex;align-items:center;gap:10px;text-decoration:none;color:inherit;
  margin-top:16px;padding:13px 15px;border-radius:14px;
  background:var(--en-brand-soft);border:1px solid var(--en-brand-line);
}
.extra .t{font-size:14.5px;font-weight:650;color:#8a3d0f}
.extra .d{font-size:12px;color:#9a5a33;margin-top:2px}
.extra .go{margin-left:auto;color:var(--en-brand);font-size:18px}

/* ---------- 站点页头（与数学站一致） ---------- */
.en-nav{position:sticky;top:0;z-index:50;height:54px;background:rgba(255,255,255,.9);
  backdrop-filter:saturate(1.4) blur(10px);border-bottom:1px solid #e6e8ee}
.en-nav-in{max-width:1180px;margin:0 auto;height:100%;display:flex;align-items:center;gap:8px;padding:0 16px}
.en-brand{display:flex;align-items:center;gap:9px;font-weight:700;color:#171a21;
  text-decoration:none;letter-spacing:-.01em;white-space:nowrap}
.en-brand .logo{width:25px;height:25px;border-radius:7px;display:grid;place-items:center;
  background:linear-gradient(135deg,#2563eb,#7c3aed);color:#fff;font-size:13px;font-weight:800}
.en-brand small{color:#727c8b;font-weight:500;font-size:12.5px}
.en-links{margin-left:auto;display:flex;gap:2px;align-items:center}
.en-links a{color:#3d4551;font-size:14px;font-weight:600;padding:7px 11px;border-radius:9px;
  text-decoration:none;white-space:nowrap}
.en-links a.active{background:#eef3ff;color:#1d4ed8}
@media(max-width:680px){
  .en-brand small{display:none}
  .en-links a{font-size:12.5px;padding:6px 8px}
}
@media(max-width:430px){
  .en-brand{font-size:0;gap:0}
  .en-brand .logo{font-size:12px;width:23px;height:23px}
  .en-links a{font-size:12px;padding:6px 7px;letter-spacing:-.2px}
}