/* ==========================================================================
   Lesson page — big video, chapters beside it; under the video: Ask AI,
   short notes and questions. Transcript and menu slide in from the sides.
   ========================================================================== */

/* ---------------- page shell: no fixed sidebar here, the lesson gets the full width ---------------- */
.lx-app{display:block}
.lx-page{padding-top:18px;max-width:1640px;margin:0 auto}
.lx-app .side{position:fixed;left:0;top:0;z-index:160;display:flex;width:300px;max-width:86vw;height:100svh;transform:translateX(-104%);visibility:hidden;
  transition:transform .65s var(--ease-out),visibility 0s .65s;box-shadow:40px 0 90px -40px rgba(0,0,0,.6)}
.lx-app.menu-on .side{transform:none;visibility:visible;transition:transform .65s var(--ease-out),visibility 0s}
.lx-app .side .brand{padding-right:36px}
.side-x{position:absolute;right:12px;top:22px;width:40px;height:40px;border-radius:12px;display:grid;place-items:center;color:rgba(255,255,255,.6);transition:background .3s,color .3s}
.side-x svg{width:18px;height:18px}
.side-scrim{position:fixed;inset:0;z-index:150;background:rgba(7,11,20,.5);-webkit-backdrop-filter:blur(5px);backdrop-filter:blur(5px);opacity:0;visibility:hidden;transition:opacity .5s,visibility 0s .5s}
.lx-app.menu-on .side-scrim{opacity:1;visibility:visible;transition:opacity .5s,visibility 0s}

.lx-top{display:flex;align-items:center;gap:10px;margin-bottom:16px}
.lx-menu,.lx-back{width:46px;height:46px;border-radius:14px;display:grid;place-items:center;background:#fff;border:1px solid var(--line-l);flex:none;transition:border-color .3s,background .3s,color .3s}
.lx-menu{position:relative;background:var(--ink);border-color:var(--ink);color:#fff}
.lx-menu i{position:absolute;left:14px;right:14px;height:2px;border-radius:2px;background:currentColor;transition:transform .5s var(--ease-out),width .4s var(--ease-out)}
.lx-menu i:nth-child(1){top:16px}.lx-menu i:nth-child(2){top:22px;right:20px}.lx-menu i:nth-child(3){top:28px}
.lx-back svg{width:18px;height:18px;transform:rotate(180deg)}
.crumbs{display:flex;align-items:center;gap:10px;margin-left:6px;font-size:13.5px;font-weight:500;color:var(--ink-3);min-width:0;white-space:nowrap;overflow:hidden}
.crumbs a{color:var(--ink-2)}
.crumbs i{font-style:normal;opacity:.45}
.lx-top .sp{margin-left:auto;display:flex;align-items:center;gap:10px}

.lx{display:grid;grid-template-columns:minmax(0,1fr) clamp(300px,23vw,372px);gap:20px;align-items:start}
.lx-left{display:flex;flex-direction:column;gap:16px;min-width:0}
.lx-rail{position:sticky;top:18px;min-width:0}

/* ---------------- player ---------------- */
/* A true 16:9 frame at every size, so the recording fills it edge to edge with no black bars.
   It is only made narrower (never squashed) when the screen is too short to show the whole video. */
.player{position:relative;aspect-ratio:16/9;width:min(100%,calc((100svh - 108px) * 16 / 9));margin-inline:auto;border-radius:26px;overflow:hidden;background:#000;isolation:isolate;
  box-shadow:0 34px 70px -36px rgba(11,18,34,.55)}
.poster{position:absolute;inset:0;z-index:2;cursor:pointer;transition:opacity .6s var(--ease-out),visibility .6s}
.poster.gone{opacity:0;visibility:hidden}
.poster-img{position:absolute;inset:0;width:100%;height:100%;max-width:none;object-fit:cover;object-position:64% 24%;transform:scale(1.03);transition:transform 1.4s var(--ease-out)}
.poster-veil{position:absolute;inset:0;background:linear-gradient(90deg,rgba(7,11,20,.94) 0%,rgba(7,11,20,.62) 36%,rgba(7,11,20,.08) 68%),linear-gradient(0deg,rgba(7,11,20,.75) 0%,rgba(7,11,20,0) 42%)}
.poster-copy{position:absolute;left:clamp(20px,4.4%,52px);bottom:clamp(20px,7%,58px);max-width:50%;color:#fff}
.poster-k{font-family:var(--f-mono);font-size:12px;letter-spacing:.16em;text-transform:uppercase;color:rgba(255,255,255,.62)}
.poster-copy b{display:block;margin-top:10px;font-family:var(--f-si-d);font-weight:800;font-size:clamp(28px,3.6vw,68px);line-height:1.16}
.poster-resume{display:inline-flex;align-items:center;gap:8px;margin-top:14px;height:32px;padding:0 13px;border-radius:999px;font-size:13px;font-weight:600;background:rgba(255,90,31,.2);color:#FFC2A6;border:1px solid rgba(255,138,61,.35)}
.poster-play{position:absolute;left:62%;top:50%;width:104px;height:104px;margin:-52px 0 0 -52px;border-radius:50%;display:grid;place-items:center;color:#fff;
  background:rgba(255,255,255,.16);border:1px solid rgba(255,255,255,.42);-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);
  transition:transform .6s var(--ease-out),background .4s}
.poster-play::before{content:"";position:absolute;inset:-14px;border-radius:50%;border:1px solid rgba(255,255,255,.24);animation:lxping 2.4s var(--ease-out) infinite}
@keyframes lxping{0%{transform:scale(.8);opacity:1}100%{transform:scale(1.35);opacity:0}}
.poster-play svg{width:34px;height:34px;margin-left:5px}
.poster.loading .poster-play svg{display:none}
.poster.loading .poster-play::after{content:"";width:30px;height:30px;border-radius:50%;border:3px solid rgba(255,255,255,.3);border-top-color:#fff;animation:spin .8s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}
.poster-dur{position:absolute;right:16px;bottom:16px;height:28px;padding:0 10px;border-radius:9px;display:inline-flex;align-items:center;font-family:var(--f-mono);font-size:12px;color:#fff;background:rgba(7,11,20,.72)}
.frame{position:absolute;inset:0;z-index:1;background:#000}
.frame iframe,#ytFrame{position:absolute;inset:0;width:100%;height:100%;border:0}
.vfail{position:absolute;inset:0;z-index:4;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:16px;padding:24px;text-align:center;color:#fff;background:rgba(7,11,20,.92)}
.vfail p{margin:0;max-width:30em;color:rgba(255,255,255,.8)}
.vfail[hidden],.vfail [hidden],.frame[hidden],.poster-resume[hidden]{display:none}

/* ---------------- title + the small buttons under the video ---------------- */
.lx-head{display:flex;align-items:center;justify-content:space-between;gap:20px;padding:0 4px}
.lx-head h1{margin:0 0 6px;font-family:var(--f-si-d);font-weight:800;font-size:clamp(30px,2.6vw,46px);line-height:1.2;letter-spacing:0;color:var(--ink)}
.lx-meta{display:flex;flex-wrap:wrap;gap:8px 18px;font-size:13.5px;color:var(--ink-2)}
.lx-meta span{display:inline-flex;align-items:center;gap:7px}
.lx-meta svg{width:16px;height:16px;color:var(--ink-3)}
.lx-acts{display:flex;gap:8px;flex:none}
.lx-text{gap:8px;padding:0 16px 0 13px;background:#fff}
.lx-text .ic{display:grid;place-items:center}
.lx-text .ic svg{width:16px;height:16px}
.lx-text[aria-expanded="true"]{background:var(--ink);color:#fff;border-color:var(--ink)}
.lx-explain .arr svg{width:15px;height:15px}

/* ---------------- chapters (right of the video) ---------------- */
.chaps{padding:20px 0 0;border-radius:26px}
.chaps .card-h{margin:0 20px 14px}
.seg-bar{display:flex;gap:4px;height:6px;margin:0 20px 10px}
.seg-bar span{position:relative;flex:var(--g) 1 0;border-radius:6px;background:var(--ivory-2);overflow:hidden;cursor:pointer}
.seg-bar span i{position:absolute;inset:0;background:linear-gradient(90deg,var(--ember),var(--amber));transform-origin:left;transform:scaleX(var(--p,0));transition:transform .5s linear}
.chap-list{display:flex;flex-direction:column}
.chap{position:relative;display:grid;grid-template-columns:46px 1fr;gap:10px;align-items:baseline;text-align:left;padding:clamp(11px,1.5vh,16px) 20px;transition:background .3s}
.chap::before{content:"";position:absolute;left:0;top:8px;bottom:8px;width:3px;border-radius:0 3px 3px 0;background:var(--ember);transform:scaleY(0);transition:transform .4s var(--ease-out)}
.chap time{font-family:var(--f-mono);font-size:12px;color:var(--ink-3);transition:color .3s}
.chap span{font-family:var(--f-si);font-size:14.5px;line-height:1.5;color:var(--ink-2);transition:color .3s}
.chap.here{background:linear-gradient(90deg,#FFF1EA,#FFF8F4)}
.chap.here::before{transform:none}
.chap.here time{color:var(--ember);font-weight:600}
.chap.here span{color:var(--ink);font-weight:600}
.chap-stats{display:grid;grid-template-columns:repeat(3,1fr);margin-top:8px;padding:16px 12px 18px;border-top:1px solid var(--line-l);text-align:center}
.chap-stats b{display:block;font-family:var(--f-display);font-weight:600;font-size:24px;letter-spacing:-.03em;line-height:1.1}
.chap-stats span{font-size:12px;color:var(--ink-3)}

.upnext{display:block;margin-top:14px;padding:16px 18px 18px;border-radius:24px;transition:border-color .3s,transform .5s var(--ease-out)}
.up-k{font-family:var(--f-mono);font-size:10.5px;letter-spacing:.16em;text-transform:uppercase;color:var(--ink-3)}
.up-row{display:flex;align-items:center;gap:12px;margin-top:10px}
.up-th{width:62px;height:44px;border-radius:12px;display:grid;place-items:center;flex:none;color:#fff;background:linear-gradient(135deg,#FF8A3D,#C7390A)}
.up-th svg{width:16px;height:16px}
.up-row b{display:block;font-size:14.5px;font-weight:650;letter-spacing:-.01em;line-height:1.3}
.up-row div span{font-size:12.5px;color:var(--ink-3)}
.up-go{margin-left:auto;width:34px;height:34px;border-radius:50%;display:grid;place-items:center;background:var(--ivory);flex:none;transition:background .3s,color .3s}
.up-go svg{width:14px;height:14px}

/* ---------------- tabs + panels ---------------- */
.lx-tabs{display:flex;gap:6px;padding:5px;border-radius:18px;background:var(--ivory-2);width:max-content;max-width:100%;overflow-x:auto;scrollbar-width:none;margin-top:6px}
.lx-tabs::-webkit-scrollbar{display:none}
.lx-tabs button{display:inline-flex;align-items:center;gap:8px;height:44px;padding:0 18px;border-radius:13px;font-weight:600;font-size:14.5px;color:var(--ink-3);white-space:nowrap;transition:color .3s,background .3s,box-shadow .3s}
.lx-tabs button svg{width:16px;height:16px}
.lx-tabs button[aria-selected="true"]{background:#fff;color:var(--ink);box-shadow:0 4px 14px -4px rgba(11,18,34,.18)}
.lx-tabs button[data-tab="ai"][aria-selected="true"] svg{color:var(--blue)}
.panel{display:none}
.panel.on{display:block;animation:lxrise .45s var(--ease-out)}
@keyframes lxrise{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:none}}
.panel-h{display:flex;align-items:flex-end;justify-content:space-between;gap:16px;margin:2px 0 16px}
.panel-h h2{margin:0;font-family:var(--f-display);font-weight:600;font-size:clamp(24px,2vw,32px);letter-spacing:-.035em}
.panel-h p{margin:4px 0 0;color:var(--ink-3);font-size:14px}

/* ---------------- Ask AI (first tab, under the video) ---------------- */
.aibox{display:flex;flex-direction:column;height:clamp(470px,68svh,680px);border-radius:26px;background:#fff;border:1px solid var(--line-l);overflow:hidden;box-shadow:0 30px 60px -44px rgba(11,18,34,.45)}
.ai-h{display:flex;align-items:center;gap:12px;padding:16px 16px 14px 20px;border-bottom:1px solid var(--line-l);background:linear-gradient(180deg,#fff,#FBFAF7)}
.ai-ic{width:42px;height:42px;border-radius:13px;display:grid;place-items:center;flex:none;color:#fff;background:linear-gradient(135deg,var(--blue),var(--cyan));box-shadow:0 10px 24px -10px rgba(61,107,255,.7)}
.ai-ic svg{width:19px;height:19px}
.ai-h b{display:block;font-size:16px;font-weight:650;letter-spacing:-.01em}
.ai-clear{margin-left:auto;width:40px;height:40px;border-radius:12px;display:grid;place-items:center;color:var(--ink-3);transition:background .3s,color .3s}
.ai-clear svg{width:18px;height:18px}
.ai-log{flex:1;min-height:0;overflow-y:auto;padding:20px 22px 10px;display:flex;flex-direction:column;gap:12px;overscroll-behavior:contain;scrollbar-width:thin}
.m{max-width:min(78%,760px);padding:12px 16px;border-radius:18px;font-size:14.5px;line-height:1.6}
.m.u{align-self:flex-end;background:var(--ink);color:#fff;border-bottom-right-radius:6px;font-family:var(--f-si);white-space:pre-wrap;word-break:break-word}
.m.a{align-self:flex-start;background:var(--ivory);color:var(--ink);border-bottom-left-radius:6px;font-family:var(--f-si);font-size:15px;line-height:1.8}
.m.a p{margin:0 0 6px}
.m.a p:last-of-type{margin-bottom:0}
.m.a .eq{display:block;width:max-content;max-width:100%;margin:8px 0;padding:8px 12px;border-radius:12px;background:#EEF4FF;color:#1F46D8;font-family:var(--f-body);font-weight:600;font-size:14px}
.m.hello{font-family:var(--f-body);font-size:14.5px;line-height:1.6}
.m.hello b{display:block;margin-bottom:4px;font-size:15.5px}
.m.note{font-family:var(--f-body);font-size:14px;color:var(--ink-2)}
.m .typing{display:inline-flex;gap:5px;padding:5px 2px}
.m .typing i{width:7px;height:7px;border-radius:50%;background:var(--ink-3);animation:blink 1.2s infinite}
.m .typing i:nth-child(2){animation-delay:.15s}.m .typing i:nth-child(3){animation-delay:.3s}
.ai-sugg{display:flex;flex-wrap:wrap;gap:8px;padding:10px 22px 2px}
.ai-sugg button{display:inline-flex;align-items:center;gap:8px;min-height:38px;padding:7px 14px;border-radius:999px;border:1px solid var(--line-l2);background:#fff;text-align:left;
  font-family:var(--f-si);font-size:13.5px;line-height:1.4;color:var(--ink-2);transition:border-color .3s,color .3s,background .3s,transform .4s var(--ease-out)}
.ai-sugg button svg{width:13px;height:13px;flex:none;color:var(--ember)}
.ai-ask{display:flex;align-items:flex-end;gap:10px;margin:12px 20px 18px;padding:7px 7px 7px 18px;border-radius:20px;border:1.5px solid var(--line-l2);background:#fff;transition:border-color .3s,box-shadow .3s}
.ai-ask:focus-within{border-color:var(--ember);box-shadow:0 0 0 4px rgba(255,90,31,.12)}
.ai-ask textarea{flex:1;min-width:0;border:0;outline:0;resize:none;background:none;font-family:var(--f-si);font-size:15.5px;line-height:1.5;max-height:130px;padding:9px 0;color:var(--ink)}
.ai-ask textarea::placeholder{color:var(--ink-3)}
.ai-ask button{display:inline-flex;align-items:center;gap:8px;height:44px;padding:0 18px 0 20px;border-radius:14px;flex:none;color:#fff;font-weight:650;font-size:14.5px;
  background:linear-gradient(180deg,#FF6A2E,#F24B12);box-shadow:0 10px 24px -10px rgba(255,90,31,.8);transition:opacity .3s,transform .3s}
.ai-ask button:disabled{opacity:.4;cursor:default;box-shadow:none}
.ai-ask button svg{width:16px;height:16px}

/* ---------------- mind map ---------------- */
.mind{position:relative;display:grid;grid-template-columns:minmax(0,1fr) minmax(0,.9fr) minmax(0,1fr);grid-template-rows:repeat(3,minmax(0,1fr));gap:18px 30px;
  padding:26px;margin-bottom:16px;border-radius:26px;background:#fff;border:1px solid var(--line-l);isolation:isolate;overflow:hidden}
.mind::before{content:"";position:absolute;inset:0;z-index:-2;background-image:radial-gradient(rgba(11,18,34,.07) 1px,transparent 1px);background-size:18px 18px}
.mind-lines{position:absolute;inset:0;width:100%;height:100%;z-index:-1}
.mind-lines path{fill:none;stroke-width:2.2;stroke-linecap:round;vector-effect:non-scaling-stroke}
.mind-c{grid-column:2;grid-row:2;align-self:center;justify-self:center;padding:16px 22px;border-radius:24px;text-align:center;color:#fff;
  background:linear-gradient(135deg,#FF5A1F,#FF8A3D);box-shadow:0 18px 40px -16px rgba(255,90,31,.7);font-family:var(--f-si-d);font-weight:800;font-size:clamp(19px,1.6vw,24px);line-height:1.25}
.mind-c small{display:block;margin-bottom:4px;font-family:var(--f-mono);font-weight:500;font-size:10.5px;letter-spacing:.16em;color:rgba(255,255,255,.8)}
.mind-b{align-self:center;padding:12px 14px;border-radius:16px;background:#fff;border:1.5px solid color-mix(in srgb,var(--mc) 45%,transparent);
  box-shadow:0 12px 26px -20px rgba(11,18,34,.45)}
.mind-b b{display:flex;align-items:center;gap:8px;font-family:var(--f-si);font-weight:600;font-size:14.5px;color:var(--ink)}
.mind-b b::before{content:"";width:9px;height:9px;border-radius:50%;flex:none;background:var(--mc)}
.mind-b ul{margin:6px 0 0;padding:0;list-style:none}
.mind-b li{position:relative;padding-left:14px;font-family:var(--f-si);font-size:13px;line-height:1.6;color:var(--ink-2)}
.mind-b li::before{content:"";position:absolute;left:3px;top:.72em;width:5px;height:2px;border-radius:2px;background:var(--mc)}

/* ---------------- notes ---------------- */
.notes{display:grid;gap:14px}
.ngrp{padding:22px 24px;border-radius:24px;background:#fff;border:1px solid var(--line-l)}
.ngrp h3{display:flex;align-items:center;gap:10px;margin:0;font-family:var(--f-si);font-weight:600;font-size:19px;line-height:1.4;color:var(--ink)}
.ngrp h3 i{font-style:normal;font-family:var(--f-mono);font-size:11.5px;font-weight:500;color:var(--ember);letter-spacing:.06em}
.ngrp > p{margin:4px 0 6px;font-family:var(--f-si);font-size:14px;line-height:1.7;color:var(--ink-3)}
.ncard{position:relative;margin-top:10px;padding:14px 16px;border-radius:16px;background:var(--ivory)}
.ncard h4{margin:0 0 6px;padding-right:84px;font-family:var(--f-si);font-weight:600;font-size:15.5px;line-height:1.55;color:var(--ink)}
.ncard p,.ncard li,.ncard dd{font-family:var(--f-si);font-size:14.5px;line-height:1.8;color:var(--ink-2)}
.ncard p{margin:0}
.ncard ul{margin:4px 0 0;padding-left:20px}
.ncard li::marker{color:var(--ember)}
.ncard b{color:var(--ink);font-weight:600}
.ncard .eq{display:inline-block;margin-top:10px;padding:8px 14px;border-radius:12px;background:#EEF4FF;color:#1F46D8;font-family:var(--f-body);font-weight:600;font-size:15px}
.ncard dl{display:grid;grid-template-columns:auto 1fr;gap:6px 14px;margin:4px 0 0}
.ncard dt{font-family:var(--f-mono);font-size:13px;font-weight:600;color:var(--ember);padding-top:3px}
.ncard dd{margin:0}
.ncard .nt{position:absolute;right:12px;top:11px;margin:0;height:28px;padding:0 11px;background:#fff;border:1px solid var(--line-l)}
.swatch{display:inline-block;width:11px;height:11px;border-radius:3px;vertical-align:-1px;margin-right:6px;border:1px solid rgba(11,18,34,.14)}

/* download the short note: sits at the end of the notes */
.dl-note{position:relative;display:flex;align-items:center;gap:16px;margin-top:16px;padding:22px 24px;border-radius:24px;color:#fff;background:var(--mid);overflow:hidden;isolation:isolate}
.dl-note::before{content:"";position:absolute;z-index:-1;width:380px;height:380px;right:-120px;top:-220px;border-radius:50%;background:radial-gradient(circle,rgba(255,90,31,.55),transparent 65%)}
.dl-ic{width:48px;height:48px;border-radius:15px;display:grid;place-items:center;flex:none;background:rgba(255,255,255,.1);border:1px solid rgba(255,255,255,.16)}
.dl-ic svg{width:22px;height:22px}
.dl-note b{display:block;font-family:var(--f-display);font-weight:600;font-size:20px;letter-spacing:-.025em}
.dl-note > div span{font-size:13.5px;color:rgba(255,255,255,.6)}
.dl-note .btn{margin-left:auto;flex:none}
.dl-note .btn .arr svg{width:15px;height:15px}

/* ---------------- questions ---------------- */
.qbar{display:flex;align-items:center;gap:14px;margin-bottom:14px;font-size:13.5px;font-weight:600;color:var(--ink-2)}
.qbar .track{flex:1;height:8px;border-radius:8px;background:var(--ivory-2);overflow:hidden}
.qbar .track i{display:block;height:100%;width:0;border-radius:8px;background:linear-gradient(90deg,var(--ember),var(--amber));transition:width .5s var(--ease-out)}
.q{padding:20px 22px;border-radius:22px;background:#fff;border:1px solid var(--line-l);margin-bottom:12px}
.q-n{font-family:var(--f-mono);font-size:11.5px;letter-spacing:.12em;text-transform:uppercase;color:var(--ink-3)}
.q-ask{margin:8px 0 14px;font-family:var(--f-si);font-weight:600;font-size:16.5px;line-height:1.7;color:var(--ink)}
.opts{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.opt{display:flex;gap:12px;align-items:flex-start;text-align:left;padding:12px 14px;border-radius:14px;border:1.5px solid var(--line-l2);background:#fff;
  font-family:var(--f-si);font-size:15px;line-height:1.6;color:var(--ink);transition:border-color .25s,background .25s,transform .3s var(--ease-out)}
.opt .k{font-family:var(--f-mono);font-size:12px;font-weight:600;color:var(--ink-3);padding-top:3px;flex:none}
.opt:disabled{cursor:default}
.opt.right{border-color:#12A36B;background:#EAF8F1}.opt.right .k{color:#12A36B}
.opt.wrong{border-color:var(--ember);background:#FFF1EA}.opt.wrong .k{color:var(--ember)}
.verdict{margin-top:12px;padding:14px 16px;border-radius:16px;background:var(--ivory)}
.verdict .head{display:flex;align-items:center;gap:8px;font-weight:700;font-size:14px}
.verdict .head svg{width:16px;height:16px}
.verdict.good .head{color:#12A36B}.verdict.bad .head{color:var(--ember)}
.verdict p{margin:6px 0 0;font-family:var(--f-si);font-size:14.5px;line-height:1.75;color:var(--ink-2)}
.recall{margin-top:10px;padding:10px 12px;border-radius:12px;background:#fff;border-left:3px solid var(--ember);font-family:var(--f-si);font-size:14px;line-height:1.6;color:var(--ink-2)}
.recall b{font-family:var(--f-body);font-weight:700;color:var(--ink)}
.ts{display:inline-flex;align-items:center;gap:7px;margin-top:10px;height:32px;padding:0 13px;border-radius:999px;background:#FFEDE4;color:var(--ember);
  font-family:var(--f-body);font-size:12.5px;font-weight:650;transition:background .3s,color .3s}
.ts svg{width:11px;height:11px}
.qscore{padding:30px 26px;border-radius:24px;text-align:center;color:#fff;background:var(--mid);position:relative;overflow:hidden;isolation:isolate}
.qscore::before{content:"";position:absolute;z-index:-1;width:420px;height:420px;left:50%;top:-260px;margin-left:-210px;border-radius:50%;background:radial-gradient(circle,rgba(255,90,31,.5),transparent 65%)}
.qscore b{display:block;font-family:var(--f-display);font-weight:700;font-size:56px;letter-spacing:-.05em;line-height:1}
.qscore p{margin:8px 0 18px;color:rgba(255,255,255,.7)}
.qscore[hidden]{display:none}

/* ---------------- transcript: slides in from the right ---------------- */
.tdraw{position:fixed;right:0;top:0;z-index:140;display:flex;flex-direction:column;width:min(440px,100vw);height:100svh;background:#fff;border-left:1px solid var(--line-l);
  box-shadow:-40px 0 90px -50px rgba(11,18,34,.5);transform:translateX(104%);visibility:hidden;transition:transform .65s var(--ease-out),visibility 0s .65s}
.tdraw.open{transform:none;visibility:visible;transition:transform .65s var(--ease-out),visibility 0s}
.tdraw-h{display:flex;align-items:center;gap:12px;padding:18px 16px 16px 22px;border-bottom:1px solid var(--line-l)}
.tdraw-h b{display:block;font-family:var(--f-display);font-weight:600;font-size:22px;letter-spacing:-.03em}
.tdraw-h span{font-size:13px;color:var(--ink-3)}
.tdraw-x{margin-left:auto;width:42px;height:42px;border-radius:13px;display:grid;place-items:center;background:var(--ivory);color:var(--ink);flex:none;transition:background .3s,color .3s}
.tdraw-x svg{width:18px;height:18px}
.tscript{flex:1;min-height:0;overflow-y:auto;padding:4px 22px 28px;overscroll-behavior:contain;scrollbar-width:thin}
.tsec{padding:16px 0 12px;border-bottom:1px solid var(--line-l)}
.tsec:last-child{border-bottom:0}
.tsec h3{margin:0;font-family:var(--f-si);font-weight:600;font-size:15.5px;color:var(--ink)}
.tsec .tt{font-family:var(--f-mono);font-size:11.5px;color:var(--ember);margin-bottom:4px}
.tline{display:block;width:calc(100% + 20px);text-align:left;margin:2px -10px;padding:6px 10px;border-radius:10px;font-family:var(--f-si);font-size:15px;line-height:1.75;color:var(--ink-2);transition:background .25s,color .25s}
.tline.here{background:#FFF1EA;color:var(--ink)}

/* ---------------- hidden AI settings ---------------- */
.setup{position:fixed;inset:0;z-index:300;display:grid;place-items:center;padding:20px;background:rgba(7,11,20,.55);-webkit-backdrop-filter:blur(6px);backdrop-filter:blur(6px);overflow-y:auto}
.setup[hidden]{display:none}
.setup-box{width:min(500px,100%);padding:28px;border-radius:24px;background:#fff;box-shadow:0 40px 80px -30px rgba(0,0,0,.5)}
.setup-box h2{margin:0;font-family:var(--f-display);font-weight:600;font-size:26px;letter-spacing:-.03em}
.setup-box p{margin:6px 0 16px;font-size:14px;color:var(--ink-3)}
.setup-box label{display:block;margin-bottom:12px;font-size:13px;font-weight:600;color:var(--ink-2)}
.setup-box input,.setup-box select{display:block;width:100%;margin-top:6px;height:48px;padding:0 14px;border-radius:12px;border:1.5px solid var(--line-l2);background:#fff;font-size:15px;font-weight:400;outline:none}
.setup-box input:focus,.setup-box select:focus{border-color:var(--ember)}
.setup-row{display:flex;gap:8px;flex-wrap:wrap;margin-top:6px}
.setup-res{margin:14px 0 0!important;padding:11px 14px;border-radius:12px;font-size:13.5px!important;line-height:1.5;font-weight:500}
.setup-res:empty{display:none}
.setup-res.wait{background:var(--ivory);color:var(--ink-2)!important}
.setup-res.good{background:#EAF8F1;color:#0B7A4E!important}
.setup-res.bad{background:#FFF1EA;color:#B5390B!important}
.setup-now{margin:12px 0 0!important;font-size:13px!important}

/* ---------------- print: the short note on paper / as a PDF ---------------- */
#printDoc{display:none}
@media print{
  @page{size:A4;margin:14mm 12mm 16mm}
  html,body{background:#fff!important}
  body > *:not(#printDoc){display:none!important}
  #printDoc{display:block!important;color:#0B1222}
  *{-webkit-print-color-adjust:exact!important;print-color-adjust:exact!important}
  .pd-head{display:flex;justify-content:space-between;align-items:center;gap:20px;padding-bottom:12px;margin-bottom:16px;border-bottom:2.5px solid #FF5A1F}
  .pd-brand{display:flex;align-items:center;gap:11px}
  .pd-brand img{width:46px;height:46px}
  .pd-brand b{display:block;font-family:var(--f-display);font-size:16px;letter-spacing:-.02em}
  .pd-brand small{display:block;margin-top:2px;font-family:var(--f-mono);font-size:9px;letter-spacing:.22em;color:#FF5A1F}
  .pd-title{text-align:right}
  .pd-title h1{margin:0;font-family:var(--f-si-d);font-weight:800;font-size:26px;line-height:1.2}
  .pd-title span{font-size:11px;color:#7C8397}
  #printDoc .mind{break-inside:avoid;gap:9px 18px;padding:14px;margin-bottom:10px;border-radius:16px}
  #printDoc .mind-b{box-shadow:none;padding:8px 11px}
  #printDoc .mind-b b{font-size:13.5px}
  #printDoc .mind-b li{font-size:11.5px;line-height:1.55}
  #printDoc .mind-c{box-shadow:none;font-size:18px;padding:13px 18px}
  #printDoc .notes{display:block}
  #printDoc .ngrp{break-inside:avoid;padding:11px 14px 12px;border-radius:14px;margin-bottom:8px}
  #printDoc .ngrp h3{font-size:16.5px}
  #printDoc .ngrp > p{margin:1px 0 2px;font-size:12px;line-height:1.55}
  #printDoc .ncard{margin-top:7px;padding:8px 12px 9px;border-radius:12px}
  #printDoc .ncard h4{margin-bottom:3px;font-size:13.5px}
  #printDoc .ncard p,#printDoc .ncard li,#printDoc .ncard dd{font-size:12.5px;line-height:1.6}
  #printDoc .ncard dl{gap:3px 14px}
  #printDoc .ncard .eq{margin-top:6px;padding:5px 12px;font-size:13.5px}
  #printDoc .ncard .nt{top:8px;height:22px;padding:0 9px;font-size:10.5px;border-color:rgba(11,18,34,.14)}
}

/* ---------------- responsive ---------------- */
@media (max-width:1240px){
  .lx{grid-template-columns:minmax(0,1fr) 300px}
}
@media (max-width:980px){
  .lx-page{padding-top:12px}
  .crumbs span,.crumbs i{display:none}
  .lx{display:flex;flex-direction:column;align-items:stretch;gap:16px}
  .lx-left{display:contents}
  .player{order:1}.lx-head{order:2}.lx-rail{order:3;position:static;width:100%}.lx-tabs{order:4;margin-top:0}.panel{order:5}
  .lx-head{flex-direction:column;align-items:flex-start;gap:14px}
  .chaps{padding-top:16px}
  .chap-list{flex-direction:row;gap:8px;overflow-x:auto;padding:0 20px 16px;scrollbar-width:none}
  .chap-list::-webkit-scrollbar{display:none}
  .chap{flex:0 0 218px;grid-template-columns:auto 1fr;align-content:start;padding:11px 13px;border-radius:16px;border:1px solid var(--line-l)}
  .chap::before{display:none}
  .chap.here{border-color:var(--ember)}
  .chap-stats,.upnext{display:none}
  /* on a phone the chat is part of the page (the page scrolls, not a box inside it), and the question box stays in reach */
  .aibox{height:auto;min-height:0;overflow:visible;box-shadow:none}
  .ai-h{border-radius:26px 26px 0 0}
  .ai-log{overflow:visible;min-height:150px;overscroll-behavior:auto}
  .aibox.pin .ai-ask{position:sticky;bottom:calc(var(--bar-h,74px) + 24px);z-index:6;box-shadow:0 16px 36px -14px rgba(11,18,34,.4)}
  .m{max-width:90%;scroll-margin:90px 0 190px}
  .lx-page{padding-bottom:calc(var(--bar-h,74px) + 46px)}
  /* suggestion (off until Maleesha says yes; try it with lesson.html?stick=1): the video stays on top while the student reads or asks */
  html.stick .player{position:sticky;top:8px;z-index:40;border-radius:18px;box-shadow:0 0 0 9px var(--ivory),0 26px 44px -14px rgba(11,18,34,.55)}
  .tdraw{width:100vw;border-left:0}
}
@media (max-width:700px){
  .player{border-radius:20px}
  .poster-copy{max-width:70%}
  .poster-copy b{font-size:24px}
  .poster-k{font-size:10px}
  .poster-play{left:auto;right:18px;top:18px;margin:0;width:64px;height:64px}
  .poster-play svg{width:24px;height:24px}
  .poster-dur{display:none}
  .lx-acts{width:100%}
  .lx-acts .btn{flex:1;padding:0 14px}
  .lx-explain .arr{display:none}
  .lx-tabs{width:100%}
  .lx-tabs button{flex:1;justify-content:center;padding:0 10px}
  .ai-log{padding:16px 14px 8px}
  .ai-sugg{flex-wrap:nowrap;overflow-x:auto;padding:10px 14px 2px;scrollbar-width:none}
  .ai-sugg::-webkit-scrollbar{display:none}
  .ai-sugg button{flex:none;max-width:78vw}
  .ai-ask{margin:10px 12px 14px;padding-left:14px}
  .ai-ask button span{display:none}
  .ai-ask button{padding:0;width:44px;justify-content:center}
  .mind{display:flex;flex-direction:column;align-items:stretch;gap:10px;padding:18px}
  .mind-lines{display:none}
  .mind-c{align-self:stretch;order:-1}
  .mind-b{border-left-width:4px;border-left-color:var(--mc)}
  .opts{grid-template-columns:1fr}
  .ngrp{padding:18px}
  .panel-h{flex-direction:column;align-items:flex-start}
  .dl-note{flex-direction:column;align-items:flex-start}
  .dl-note .btn{margin-left:0;width:100%}
}

@media (hover:hover){
  .lx-back:hover{border-color:var(--ink)}
  .lx-menu:hover{background:var(--ember);border-color:var(--ember)}
  .lx-menu:hover i:nth-child(2){transform:translateX(6px)}
  .side-x:hover{background:rgba(255,255,255,.08);color:#fff}
  .poster:hover .poster-img{transform:scale(1.07)}
  .poster:hover .poster-play{transform:scale(1.08);background:var(--ember);border-color:var(--ember)}
  .chap:hover{background:var(--ivory)}
  .chap.here:hover{background:linear-gradient(90deg,#FFF1EA,#FFF8F4)}
  .chap:hover span{color:var(--ink)}
  .upnext:hover{border-color:var(--line-l2);transform:translateY(-3px)}
  .upnext:hover .up-go{background:var(--ember);color:#fff}
  .opt:not(:disabled):hover{border-color:var(--ink-3);transform:translateX(3px)}
  .tline:hover{background:var(--ivory);color:var(--ink)}
  .ts:hover{background:var(--ember);color:#fff}
  .ncard .nt:hover{border-color:var(--ember)}
  .ai-sugg button:hover{border-color:var(--ember);color:var(--ink);transform:translateY(-2px)}
  .ai-clear:hover{background:var(--ivory);color:var(--ink)}
  .ai-ask button:not(:disabled):hover{transform:scale(1.04)}
  .tdraw-x:hover{background:var(--ink);color:#fff}
  .lx-text:hover{color:#fff}
}