:root{--bg:#f7f4ee;--card:#fffdf9;--ink:#22252a;--mute:#7a7468;--line:#e7e0d4;--acc:#2f7d6b;--acc-soft:#e3f0ec;--warn:#c2683a;--hl:#fff3d6;--r:14px}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.6 -apple-system,BlinkMacSystemFont,"SF Pro Text","PingFang SC","Hiragino Sans GB","Noto Sans SC","Helvetica Neue",Arial,sans-serif}
a{color:var(--acc)}
.wrap{max-width:1080px;margin:0 auto;padding:20px 18px 80px}
header.top{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:18px}
.brand{font-weight:700;font-size:18px;text-decoration:none;color:var(--ink)}
.brand span{color:var(--acc)}
.pill{font-size:13px;color:var(--mute);background:var(--card);border:1px solid var(--line);border-radius:999px;padding:4px 12px;white-space:nowrap}
h1{font-size:26px;line-height:1.3;margin:6px 0 6px}
.sub{color:var(--mute);font-size:14px;margin:0}
.gist{background:var(--acc-soft);border-radius:var(--r);padding:12px 16px;margin:14px 0 0;font-size:15px}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r)}
/* index */
.lessons{list-style:none;padding:0;margin:18px 0 0;display:grid;gap:12px}
.lessons a{display:flex;gap:14px;align-items:flex-start;padding:16px;text-decoration:none;color:inherit}
.lessons .date{flex:none;width:58px;text-align:center;border-right:1px solid var(--line);padding-right:12px;color:var(--mute);font-size:13px;line-height:1.3}
.lessons .date b{display:block;font-size:22px;color:var(--ink)}
.lessons h2{font-size:17px;margin:0 0 4px;line-height:1.4}
.lessons p{margin:0;color:var(--mute);font-size:14px}
.done-tag{display:inline-block;font-size:12px;color:var(--acc);background:var(--acc-soft);border-radius:999px;padding:1px 8px;margin-left:6px;vertical-align:2px}
.how{margin-top:26px;padding:16px 18px;font-size:14px;color:#4a463f}
.how ol{margin:6px 0 0;padding-left:20px}
/* lesson layout */
.grid{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,1fr);gap:20px;margin-top:18px;align-items:start}
.player{position:sticky;top:12px}
.vbox{position:relative;background:#111;border-radius:var(--r);overflow:hidden;aspect-ratio:16/9}
video{width:100%;height:100%;display:block;background:#111}
.cap{min-height:64px;padding:10px 14px;font-size:17px;line-height:1.45;text-align:center;border-bottom:1px solid var(--line)}
.cap .zh{display:block;color:var(--mute);font-size:15px;margin-top:2px}
.cap.hidden-cap{color:var(--mute);font-size:14px}
.controls{padding:12px 12px 14px;display:flex;flex-direction:column;gap:10px}
.row{display:flex;flex-wrap:wrap;align-items:center;gap:8px}
.row .lab{font-size:13px;color:var(--mute);width:44px;flex:none}
button{font:inherit;font-size:14px;border:1px solid var(--line);background:#fff;color:var(--ink);border-radius:10px;padding:7px 12px;cursor:pointer;line-height:1.2;-webkit-tap-highlight-color:transparent}
button:hover{border-color:#cfc6b6}
button.on{background:var(--acc);border-color:var(--acc);color:#fff}
button.big{font-size:16px;padding:9px 16px}
.seg{display:inline-flex;border:1px solid var(--line);border-radius:10px;overflow:hidden}
.seg button{border:0;border-radius:0;border-right:1px solid var(--line)}
.seg button:last-child{border-right:0}
.loopinfo{font-size:13px;color:var(--warn)}
.steps{font-size:13px;color:var(--mute);margin:0;padding:10px 14px;border-top:1px dashed var(--line)}
.steps b{color:var(--ink)}
/* sentences */
.sents{list-style:none;margin:0;padding:6px}
.s{display:flex;gap:10px;padding:10px 10px;border-radius:10px;cursor:pointer;align-items:flex-start}
.s:hover{background:#faf6ee}
.s.cur{background:var(--hl)}
.s .n{flex:none;width:30px;font-size:12px;color:var(--mute);padding-top:3px;font-variant-numeric:tabular-nums}
.s .t{flex:1;min-width:0}
.s .en{font-size:16px}
.s .zh{font-size:14px;color:var(--mute);margin-top:2px}
.s .mask{color:transparent;background:#ebe4d6;border-radius:5px;-webkit-box-decoration-break:clone;box-decoration-break:clone;user-select:none;font-size:15px;line-height:2}
.s .eye{flex:none;border:0;background:transparent;color:var(--mute);padding:2px 6px;font-size:13px}
.s .eye:hover{color:var(--acc)}
.sechead{display:flex;justify-content:space-between;align-items:center;padding:12px 16px 6px}
.sechead h3{margin:0;font-size:16px}
.sechead small{color:var(--mute)}
.kw{list-style:none;margin:0;padding:4px 10px 12px;display:grid;gap:8px}
.kw li{padding:10px 12px;border:1px solid var(--line);border-radius:10px;background:#fff}
.kw .term{font-weight:600}
.kw .term button{margin-left:6px;padding:2px 8px;font-size:12px}
.kw .zh{color:var(--acc);font-size:14px;margin-left:4px}
.kw .note{font-size:13px;color:var(--mute);margin-top:3px}
.side{display:flex;flex-direction:column;gap:16px}
.source{padding:14px 16px;font-size:14px}
.source .who{font-weight:600}
.source p{margin:6px 0 0;color:#4a463f;white-space:pre-line}
details.full{padding:4px 6px}
details.full summary{cursor:pointer;padding:10px 10px;font-weight:600}
.fl{max-height:420px;overflow:auto;padding:0 10px 10px;font-size:14px}
.fl div{padding:3px 0;cursor:pointer;display:flex;gap:8px}
.fl div:hover{color:var(--acc)}
.fl span{color:var(--mute);font-variant-numeric:tabular-nums;flex:none;width:52px}
.finish{display:flex;justify-content:center;margin:22px 0 0}
.kbd{font-size:12px;color:var(--mute);text-align:center;margin-top:10px}
.back{font-size:14px;text-decoration:none}
@media (max-width:820px){
 .grid{grid-template-columns:1fr}
 .player{position:sticky;top:0;z-index:5;margin:0 -18px;background:var(--bg);padding:0 0 6px}
 .player .vbox{border-radius:0}
 .player .card{border-radius:0;border-left:0;border-right:0}
 .cap{min-height:54px;font-size:16px;padding:8px 12px}
 .controls{padding:8px 10px 10px;gap:8px}
 .steps,.kbd{display:none}
 h1{font-size:22px}
 .wrap{padding:14px 18px 60px}
 .row .lab{display:none}
 .controls button,.seg button{padding:6px 9px;font-size:13px}
 .controls .big{font-size:14px;padding:6px 12px}
 .cap{min-height:44px;font-size:15px;padding:6px 12px}
 .row{gap:6px;flex-wrap:wrap}
}
.s .eye:empty{display:none}
.subcover{position:absolute;left:0;right:0;display:flex;align-items:center;justify-content:center;background:rgba(30,30,30,.55);backdrop-filter:blur(14px);-webkit-backdrop-filter:blur(14px);color:#eee;font-size:12px;cursor:pointer;letter-spacing:.5px}
.subcover[hidden]{display:none}
/* index filters */
.filters{margin-top:18px;padding:12px 14px;display:flex;flex-direction:column;gap:8px}
.filters input{font:inherit;font-size:15px;width:100%;padding:9px 12px;border:1px solid var(--line);border-radius:10px;background:#fff;outline:none}
.filters input:focus{border-color:var(--acc)}
.frow{display:flex;gap:8px;align-items:flex-start}
.flab{flex:none;width:34px;font-size:13px;color:var(--mute);padding-top:5px}
.chips{display:flex;flex-wrap:wrap;gap:6px}
.chip{font-size:13px;padding:4px 11px;border-radius:999px;background:#fff}
.chip small{color:var(--mute);font-size:11px}
.chip.on small{color:#d8efe8}
.fmeta{display:flex;justify-content:space-between;align-items:center;font-size:13px;color:var(--mute)}
button.link{border:0;background:none;color:var(--acc);padding:0;font-size:13px}
.empty{color:var(--mute);text-align:center;margin:24px 0}
.lessons .body{min-width:0}
.lessons .meta{display:flex;flex-wrap:wrap;gap:6px;margin-top:8px;font-size:12px}
.lessons .meta span{border-radius:999px;padding:1px 8px;background:#f1ece2;color:#5e584d}
.lessons .meta .tg{background:var(--acc-soft);color:var(--acc)}
.lessons .meta .lv0{background:#e4f2e0;color:#3f7a33}.lessons .meta .lv1{background:#fbefd5;color:#9a6a10}.lessons .meta .lv2{background:#f8e1d8;color:#a64b2a}
.lesson-meta{display:flex;flex-wrap:wrap;gap:6px;margin-top:8px;font-size:12px}
.lesson-meta span{border-radius:999px;padding:1px 9px;background:#f1ece2;color:#5e584d}
.lesson-meta .tg{background:var(--acc-soft);color:var(--acc)}