/* Drag-in reveal (eboxlab.net home page): one cursor drags each block's frame in from off-screen, drops it, the frame shows
   its handles and W × H, the content wipes in, frame and cursor fade. Transforms, opacity and clip-path only. */
html.di-on body{position:relative}
html.di-on [data-di="wait"]{-webkit-clip-path:inset(0 0 100% 0);clip-path:inset(0 0 100% 0)}
.di-layer{position:absolute;left:0;top:0;width:100%;height:100%;overflow:hidden;pointer-events:none;z-index:40;contain:strict}
.di-ov{position:absolute;left:0;top:0;--c:#89cff0;--ink:#071430;will-change:transform,opacity}
.di-ov.lt{--c:#1d5fa8}
.di-box{position:absolute;inset:0;box-sizing:border-box;border:1.5px dashed var(--c);border-radius:10px;
  background:rgba(137,207,240,.10);box-shadow:0 26px 60px rgba(3,10,26,.45)}
.di-ov.lt .di-box{background:rgba(29,95,168,.07);box-shadow:0 26px 60px rgba(10,31,68,.20)}
.di-ov.dropped .di-box{border-style:solid;box-shadow:none;transition:box-shadow .2s}
.di-n{position:absolute;box-sizing:border-box;border:1px solid var(--c);border-radius:6px;opacity:.45}
.di-h{position:absolute;width:8px;height:8px;box-sizing:border-box;background:#fff;border:1.5px solid var(--c);opacity:0;transform:scale(.3);transition:opacity .12s,transform .16s}
.di-h.a{left:-4px;top:-4px}.di-h.b{right:-4px;top:-4px}.di-h.c{left:-4px;bottom:-4px}.di-h.d{right:-4px;bottom:-4px}
.di-ov.dropped .di-h{opacity:1;transform:none}
.di-tag,.di-sz{position:absolute;font:600 10px/1 "Martian Mono",ui-monospace,Menlo,monospace;letter-spacing:.04em;padding:4px 7px;white-space:nowrap;opacity:0;transition:opacity .14s}
.di-tag{left:-1px;bottom:100%;margin-bottom:5px;background:#071430;color:#fff}
.di-sz{top:100%;left:50%;margin-top:6px;transform:translateX(-50%);background:#89cff0;color:#071430;font-variant-numeric:tabular-nums}
.di-ov.dropped .di-tag,.di-ov.dropped .di-sz{opacity:1}
.di-cur{position:absolute;top:-6px;width:30px;height:30px;will-change:transform}
.di-ov.fl .di-cur{right:-14px}.di-ov.fr .di-cur{left:-14px}
.di-cur svg{position:absolute;inset:0;width:30px;height:30px;transform-origin:50% 20%;filter:drop-shadow(0 2px 3px rgba(3,10,26,.5))}
.di-cur .arrow{opacity:0}.di-ov.dropped .di-cur .arrow{opacity:1}.di-ov.dropped .di-cur .hand{opacity:0}
/* where this engine runs it is the entrance: the page's own scroll reveal steps aside */
html.di-on [data-drag-in] .rv,html.di-on [data-drag-in].rv,html.di-on [data-drag-in] .head h2,html.di-on [data-drag-in].head h2{animation:none!important;transition:none;transform:none}
@media print{html.di-on [data-di]{-webkit-clip-path:none!important;clip-path:none!important}.di-layer{display:none!important}}

@media (min-width:900px){.di-cur svg{transform:scale(1.35)}}
/* Section pictures and line art (eboxlab.net home). Line art = thin engineering drawings in the palette (--lab: baby blue
   on dark, #1d5fa8 on light) that draw themselves on scroll. A .la-slot drawing lives in its section's top padding, so it
   can never sit on text; it is absolutely placed, so it never moves the layout. */
.la{display:block;overflow:visible;pointer-events:none;color:var(--lab)}
.la path{stroke-dasharray:1 1}
.la .thin{stroke-width:.9;opacity:.75}
.la .dot{fill:currentColor;stroke:none}
.la-slot{position:absolute;z-index:1;--h:calc(clamp(72px,9vw,128px) - clamp(22px,3vw,36px));height:var(--h);width:calc(var(--h) * var(--ar));
  top:clamp(11px,1.5vw,18px);right:max(var(--pad),calc((100% - var(--max)) / 2 + var(--pad)))}
@media (prefers-reduced-motion:no-preference){
  @supports (animation-timeline:view()){
    .la{view-timeline-name:--la}
    .la path{animation:la-draw linear both;animation-timeline:--la;animation-range:cover 6% cover 40%}
    .la .g2 path{animation-range:cover 12% cover 47%}
    .la .g3 path{animation-range:cover 18% cover 54%}
    .la .dot{animation:la-pop linear both;animation-timeline:--la;animation-range:cover 28% cover 52%}
  }
  /* no scroll-driven animations (sections.js adds .la-io): draw once when seen */
  .la-io .la path{stroke-dashoffset:1}
  .la-io .la .dot{opacity:0}
  /* .la-go comes two frames after .la-io, so a drawing already on screen does not first un-draw itself */
  .la-go .la path{transition:stroke-dashoffset 1.5s cubic-bezier(.3,.6,.2,1)}
  .la-go .la .g2 path{transition-delay:.25s}
  .la-go .la .g3 path{transition-delay:.5s}
  .la-go .la .dot{transition:opacity .6s .9s}
  .la-io .la.in path{stroke-dashoffset:0}
  .la-io .la.in .dot{opacity:1}
}
@keyframes la-draw{from{stroke-dashoffset:1}to{stroke-dashoffset:0}}
@keyframes la-pop{from{opacity:0}to{opacity:1}}
/* Online course pages (/online/<course>/ and its lessons). Same type and palette as the home page: Archivo + Martian Mono,
   navy and baby blue, white reading sheets. Built by qa/course.py, which puts drag-in.css and the line-art rules of
   sections.css in front of this file. */
:root{
  --deep:#071430;--navy:#0a1f44;--navy2:#10306a;--panel:#0d2551;
  --baby:#89cff0;--baby3:#bfe6fa;--note:#d9eefb;
  --ink:#0a1f44;--ink2:#213c66;--soft:#44587a;--blue:#1d5fa8;--rule:#d3e2f0;--tint:#eef6fc;--softd:#bccbe6;
  --sans:"Archivo",system-ui,-apple-system,"Segoe UI",Helvetica,Arial,sans-serif;
  --mono:"Martian Mono",ui-monospace,"SF Mono",Menlo,Consolas,monospace;
  --pad:clamp(16px,4vw,48px);--max:1320px;
  /* right and wrong, one pair for the exercise and the quiz: green and rust on paper, mint and peach on navy */
  --ok:#0a6e44;--ok-bg:#dff7ea;--ok-d:#7ee2b8;--no:#a8380b;--no-ink:#8a2f0a;--no-bg:#fff1e6;--no-d:#ffb48a;--no-dk:#3d1300;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;background:var(--deep);scroll-padding-top:20px}
body{margin:0;background:var(--deep);color:#fff;font-family:var(--sans);font-size:17px;line-height:1.6;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
h1,h2,h3,h4,p,ul,ol,dl,dd,figure,fieldset,legend{margin:0;padding:0}
fieldset{border:0;min-width:0}
ul,ol{list-style:none}
a{color:inherit}
button,input{font:inherit;color:inherit}
img,svg,video{display:block;max-width:100%}
[hidden]{display:none!important}
:focus-visible{outline:2px solid var(--baby);outline-offset:3px;border-radius:2px}
.light :focus-visible{outline-color:var(--ink)}
.skip{position:absolute;left:12px;top:-60px;background:#fff;color:var(--navy);padding:12px 16px;font-family:var(--mono);font-size:13px;z-index:120;text-decoration:none}
.skip:focus{top:12px}
.vh{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.mono{font-family:var(--mono);font-stretch:87.5%;font-size:12.5px;line-height:1.6;letter-spacing:.01em}
.light{background:#fff;color:var(--ink);--lab:var(--blue)}
.dark{--lab:var(--baby)}
.ico{width:18px;height:18px;flex:none}
.mk{display:grid;place-items:center;width:22px;height:22px;border-radius:50%;flex:none}
.mk svg{width:62%;height:62%;stroke-width:2.6}
.thread{position:fixed;left:0;right:0;top:0;height:3px;z-index:90;pointer-events:none;background:rgba(7,20,48,.35)}
.thread i{display:block;height:100%;background:var(--baby);transform-origin:0 50%;transform:scaleX(0)}

/* ---------- top bar, footer ---------- */
.cbar{border-bottom:1px solid rgba(137,207,240,.18)}
.cbar .in{width:min(100%,var(--max));margin:0 auto;padding:0 var(--pad);display:flex;align-items:center;gap:8px 18px;min-height:64px}
.mark{display:inline-flex;align-items:center;gap:6px;min-height:44px;color:#fff;text-decoration:none;flex:none}
.mark img{height:38px;width:auto}
.mark i{font-style:normal;color:var(--baby);border-left:1px solid rgba(137,207,240,.4);padding-left:10px;margin-left:4px;font-size:14px}
.cbar .where{margin-left:auto;display:inline-flex;align-items:center;min-height:44px;padding:0 4px;color:#fff;text-underline-offset:4px;text-decoration-color:rgba(137,207,240,.6)}
.cbar .where:hover{color:var(--baby3)}
.chip{display:inline-flex;align-items:center;gap:7px;padding:3px 11px;border:1px solid rgba(137,207,240,.55);border-radius:999px;color:var(--baby3);white-space:nowrap}
.chip::before{content:"";width:6px;height:6px;border-radius:50%;background:var(--baby)}
.cbar .chip{margin-left:auto}
.cbar .where+.chip{margin-left:0}
.light .chip{border-color:#9db9d6;color:var(--blue)}
.light .chip::before{background:var(--blue)}
@media (max-width:520px){.cbar .where{display:none}.cbar .where+.chip{margin-left:auto}}
.cfoot{border-top:1px solid rgba(137,207,240,.18);color:var(--softd)}
.cfoot .in{width:min(100%,var(--max));margin:0 auto;padding:18px var(--pad) 28px;display:flex;flex-wrap:wrap;align-items:center;gap:4px 24px}
.cfoot a{display:inline-flex;align-items:center;min-height:44px;min-width:44px;color:#fff}

/* ---------- buttons ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:48px;padding:10px 22px;border-radius:999px;border:1px solid var(--baby);
  background:var(--baby);color:var(--deep);font-family:var(--mono);font-stretch:87.5%;font-size:13px;font-weight:600;letter-spacing:.01em;text-decoration:none;cursor:pointer}
.btn:hover{background:#fff;border-color:#fff}
.btn svg{width:16px;height:16px;flex:none}
.btn-line{background:transparent;color:#fff;border-color:rgba(255,255,255,.6)}
.btn-line:hover{background:#fff;color:var(--deep)}
.light .btn{background:var(--ink);border-color:var(--ink);color:#fff}
.light .btn:hover{background:var(--navy2);border-color:var(--navy2)}
.light .btn-line{background:#fff;color:var(--ink);border-color:var(--ink)}
.light .btn-line:hover{background:var(--tint);color:var(--ink)}

/* ---------- section heads (the drag-in engine drags these in) ---------- */
.head .mono{color:var(--lab,var(--baby))}
.head h2{margin-top:8px;font-size:clamp(1.7rem,3.6vw,2.5rem);line-height:1.06;letter-spacing:-.02em;font-weight:820;font-stretch:110%}
.head h2 em{font-weight:360;font-stretch:92%}
.dark .head h2 em{color:var(--baby3)}
.light .head h2 em{color:var(--soft)}
.head .sub{margin-top:12px;max-width:60ch;color:var(--softd)}
.light .head .sub{color:var(--ink2)}

/* ====================================================== OVERVIEW ====================================================== */
.ohero{position:relative;overflow:hidden;overflow:clip}
.ohero::before{content:"";position:absolute;inset:0;pointer-events:none;background:linear-gradient(rgba(137,207,240,.07) 1px,transparent 1px) 0 0/100% 56px,linear-gradient(90deg,rgba(137,207,240,.07) 1px,transparent 1px) 0 0/56px 100%;-webkit-mask-image:radial-gradient(80% 90% at 12% 20%,#000,transparent 78%);mask-image:radial-gradient(80% 90% at 12% 20%,#000,transparent 78%)}
.ohero .in{position:relative;width:min(100%,var(--max));margin:0 auto;padding:clamp(28px,5vw,64px) var(--pad) clamp(36px,5vw,72px);display:grid;grid-template-columns:minmax(0,7fr) minmax(0,5fr);gap:clamp(24px,4vw,56px);align-items:center}
.ohero .kick{color:var(--baby)}
.ohero h1{margin-top:14px;font-size:clamp(2.7rem,8.2vw,6rem);line-height:.96;letter-spacing:-.03em;font-weight:820;font-stretch:112%}
.ohero h1 em{font-weight:300;font-stretch:90%;color:var(--baby3)}
.ohero .sub{margin-top:20px;max-width:30ch;font-size:clamp(1.15rem,2.2vw,1.5rem);line-height:1.35;color:#fff}
.facts{display:flex;flex-wrap:wrap;gap:8px;margin-top:22px;color:#fff}
.facts li{border:1px solid rgba(137,207,240,.4);border-radius:999px;padding:3px 12px}
.buy{display:flex;flex-wrap:wrap;align-items:center;gap:14px 22px;margin-top:28px;padding-top:22px;border-top:1px solid rgba(137,207,240,.22)}
.price{display:flex;align-items:baseline;gap:10px;font-family:var(--mono);font-stretch:87.5%}
.price b{font-size:clamp(2.2rem,5vw,3rem);line-height:1;font-weight:600;letter-spacing:-.02em}
.price span{font-size:12.5px;color:var(--softd)}
.buy .quiet{flex-basis:100%;color:var(--softd)}
.ofig{position:relative;margin:0;border-radius:18px;border:1px solid rgba(137,207,240,.3);background:#0b1f45;aspect-ratio:1/1;max-height:560px;justify-self:end;width:100%}
.ofig img{width:100%;height:100%;object-fit:cover;border-radius:17px}
.ofig .la{position:absolute;left:-28px;bottom:-22px;height:92px;width:auto;aspect-ratio:var(--ar);color:var(--baby);background:var(--deep);padding:10px;border:1px solid rgba(137,207,240,.3);border-radius:12px;box-sizing:content-box}
@media (max-width:860px){
  .ohero .in{grid-template-columns:minmax(0,1fr)}
  .ofig{aspect-ratio:16/11;justify-self:stretch}
  .ofig img{object-position:50% 18%}
  .ofig .la{left:auto;right:14px;bottom:-18px;height:64px}
}
.osec{position:relative;border-radius:clamp(22px,4vw,44px) clamp(22px,4vw,44px) 0 0}
.osec .in{width:min(100%,var(--max));margin:0 auto;padding:clamp(40px,6vw,84px) var(--pad)}
.osec.dark{background:var(--deep)}
.osec.light+.osec.dark,.osec.dark+.osec.light{margin-top:calc(-1 * clamp(22px,4vw,44px))}
.osec.light+.osec.dark{border-radius:0}
.osec.light:has(+.osec.dark){border-radius:clamp(22px,4vw,44px)}
.osec.light+.osec.dark .in{padding-top:calc(clamp(40px,6vw,84px) + clamp(22px,4vw,44px))}
.learn{display:grid;grid-template-columns:minmax(0,5fr) minmax(0,7fr);gap:clamp(24px,4vw,64px);align-items:start}
.learn ol{counter-reset:k;border-top:1px solid var(--rule)}
.learn li{counter-increment:k;display:grid;grid-template-columns:44px minmax(0,1fr);gap:8px;padding:14px 0;border-bottom:1px solid var(--rule);color:var(--ink);font-size:1.06rem;line-height:1.45}
.learn li::before{content:counter(k,decimal-leading-zero);font-family:var(--mono);font-stretch:87.5%;font-size:12.5px;line-height:1.9;color:var(--blue)}
.runs{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin-top:clamp(32px,5vw,56px)}
.runs li{padding:16px 18px 18px;border-radius:16px;background:var(--tint);border:1px solid #cfe0ef;color:var(--ink2);font-size:.98rem;line-height:1.45}
.runs b{display:block;margin:6px 0 4px;color:var(--ink);font-size:1.25rem;line-height:1.15;font-weight:800;font-stretch:108%}
.runs .mono{color:var(--blue)}
.runs li:last-child{background:var(--navy);border-color:var(--navy);color:#dbe7f8}
.runs li:last-child b{color:#fff}.runs li:last-child .mono{color:var(--baby)}
.runs li{position:relative}
.runs .ri{width:36px;height:36px;margin:0 0 12px -2px;color:var(--blue)}
.runs li:last-child .ri{color:var(--baby)}
.runs li:not(:last-child)::after{content:"";position:absolute;left:100%;top:35px;width:13px;height:2px;background:var(--baby)}
@media (max-width:900px){.learn{grid-template-columns:minmax(0,1fr)}.runs{grid-template-columns:repeat(2,minmax(0,1fr))}.runs li:not(:last-child)::after{display:none}}
@media (max-width:440px){.runs{grid-template-columns:minmax(0,1fr)}.runs li{display:grid;grid-template-columns:48px minmax(0,1fr);align-items:start}.runs li>*{grid-column:2}.runs b{margin:2px 0}.runs .ri{grid-column:1;grid-row:1/span 3;margin:2px 0 0 -2px}}
.parts{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px;margin-top:clamp(24px,4vw,44px);align-items:start}
.part{border-radius:20px;border:1px solid rgba(137,207,240,.26);background:var(--navy);overflow:hidden}
.part-img{width:100%;height:auto;aspect-ratio:16/7;object-fit:cover;background:#0b1f45}
.part-h{padding:18px clamp(16px,2.4vw,26px) 6px}
.part-h .mono{color:var(--baby)}
.part-h h3{font-size:1.6rem;line-height:1.1;font-weight:820;font-stretch:108%}
.les{padding:6px clamp(8px,1.4vw,14px) 14px}
.les li{display:grid;grid-template-columns:38px minmax(0,1fr);gap:2px 8px;align-items:start;padding:12px 10px;border-top:1px solid rgba(137,207,240,.16)}
.les li:first-child{border-top:0}
.les .n{color:var(--baby);line-height:1.75}
.les .t{color:#fff;font-weight:600;line-height:1.35}
.les .st{grid-column:2;display:inline-flex;align-items:center;gap:7px;color:var(--softd)}
.les .st svg{width:14px;height:14px}
.les a.row{grid-column:1/-1;display:grid;grid-template-columns:38px minmax(0,1fr) auto;gap:2px 8px;align-items:start;margin:-12px -10px;padding:12px 10px;border-radius:12px;text-decoration:none;color:#fff;background:rgba(137,207,240,.1);border:1px solid rgba(137,207,240,.4)}
.les a.row:hover{background:rgba(137,207,240,.18)}
.les a.row .go{grid-row:1/span 2;grid-column:3;align-self:center;display:inline-flex;align-items:center;justify-content:center;width:36px;height:36px;border-radius:50%;background:var(--baby);color:var(--deep)}
.les a.row .go svg{width:16px;height:16px}
.les a.row .st{color:var(--baby3)}
.les a.row .fm{grid-column:2;color:var(--softd)}
.les a.row .go{grid-row:1/span 3}
.les a.row.has-th{grid-template-columns:clamp(112px,26%,168px) 30px minmax(0,1fr) auto;gap:2px 12px;align-content:center}
.les a.row .th{grid-column:1;grid-row:1/span 3;align-self:center;position:relative;display:block;aspect-ratio:16/9;border-radius:9px;overflow:hidden;border:1px solid rgba(137,207,240,.4);background:#0b1f45}
.les a.row .th img{width:100%;height:100%;object-fit:cover}
.les a.row .th i{position:absolute;left:50%;top:50%;width:36px;height:36px;margin:-18px 0 0 -18px;border-radius:50%;display:grid;place-items:center;background:var(--baby);color:var(--deep);box-shadow:0 6px 18px rgba(3,10,26,.5)}
.les a.row .th i svg{width:16px;height:16px;margin-left:2px}
.les a.row.has-th .n{grid-column:2}.les a.row.has-th .t,.les a.row.has-th .st,.les a.row.has-th .fm{grid-column:3}
.les a.row.has-th .go{grid-column:4}
.les a.row:hover .th i{background:#fff}
@media (max-width:560px){
  .les a.row.has-th{grid-template-columns:30px minmax(0,1fr) auto}
  .les a.row .th{grid-column:1/-1;grid-row:1;margin-bottom:10px}
  .les a.row .th i{width:48px;height:48px;margin:-24px 0 0 -24px}.les a.row .th i svg{width:20px;height:20px}
  .les a.row.has-th .n{grid-column:1}.les a.row.has-th .t,.les a.row.has-th .st,.les a.row.has-th .fm{grid-column:2}
  .les a.row.has-th .go{grid-column:3;grid-row:2/span 3}
}
@media (max-width:860px){.parts{grid-template-columns:minmax(0,1fr)}}
.deal{display:grid;grid-template-columns:minmax(0,7fr) minmax(0,5fr);gap:clamp(20px,4vw,56px);align-items:center}
.deal .fmt{font-size:clamp(1.15rem,2vw,1.4rem);line-height:1.45;color:var(--ink);max-width:36ch}
.deal .box{padding:clamp(20px,3vw,30px);border-radius:20px;background:var(--navy);color:#fff}
.deal .box .price span{color:var(--softd)}
.deal .box .quiet{margin-top:10px;color:var(--softd)}
.deal .box .top{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:14px;color:var(--baby)}
.incl{display:grid;gap:9px;margin-top:16px;padding-top:16px;border-top:1px solid rgba(137,207,240,.22)}
.incl li{display:grid;grid-template-columns:20px minmax(0,1fr);gap:10px;line-height:1.4;color:#fff}
.incl svg{width:18px;height:18px;margin-top:3px;color:var(--baby)}
.deal .box .act{display:flex;flex-wrap:wrap;align-items:center;gap:12px;margin-top:20px}
.deal .box .act .btn{margin-top:0}
.enroll-slot{display:contents}
.deal .box .chip{border-color:rgba(137,207,240,.55);color:var(--baby3)}
.deal .box .chip::before{background:var(--baby)}
.deal .box :focus-visible{outline-color:var(--baby)}
@media (max-width:860px){.deal{grid-template-columns:minmax(0,1fr)}}

/* ====================================================== LESSON PLAYER ====================================================== */
body.player{--max:1480px}
.lp{width:min(100%,var(--max));margin:0 auto;padding:clamp(14px,2vw,24px) var(--pad) clamp(40px,6vw,80px);display:grid;grid-template-columns:300px minmax(0,1fr);gap:clamp(20px,3vw,44px);align-items:start}
.lm{min-width:0;display:grid;gap:clamp(14px,2vw,22px)}
.lm>*{min-width:0}

/* ---- lesson list ---- */
.toc{position:sticky;top:16px;max-height:calc(100vh - 32px);overflow:auto;border:1px solid rgba(137,207,240,.24);border-radius:18px;background:var(--navy)}
.toc-btn{display:none}
.toc-panel{padding:16px 12px 14px}
.toc-course{display:block;padding:4px 8px 12px;text-decoration:none;color:#fff}
.toc-course .mono{display:block;color:var(--baby)}
.toc-course b{font-size:1.3rem;line-height:1.15;font-weight:820;font-stretch:108%}
.toc-course:hover b{text-decoration:underline;text-underline-offset:4px}
.toc-prog{margin:0 8px 14px}
.meter{height:6px;border-radius:3px;background:rgba(137,207,240,.2);overflow:hidden}
.meter i{display:block;height:100%;width:100%;background:var(--baby);transform-origin:0 50%;transform:scaleX(0);transition:transform .35s cubic-bezier(.2,.7,.2,1)}
.toc-prog p{margin-top:8px;color:var(--softd)}
.toc-part{margin:14px 8px 4px;padding-top:12px;border-top:1px solid rgba(137,207,240,.18);color:var(--baby)}
.toc-list>li{display:grid;grid-template-columns:30px minmax(0,1fr);gap:0 6px;padding:9px 8px;border-radius:12px;color:#fff}
.toc-list .n{color:var(--baby);line-height:1.8}
.toc-list .t{font-size:.95rem;font-weight:600;line-height:1.35}
.toc-list .st{grid-column:2;display:flex;align-items:flex-start;gap:6px;margin-top:2px;color:var(--softd)}
.toc-list .st svg{margin-top:3px;flex:none}
.toc-list .st svg{width:13px;height:13px}
.toc-list>li.lock .t{color:#d5e0f2;font-weight:500}
.toc-list>li.cur{background:rgba(137,207,240,.1);border:1px solid rgba(137,207,240,.34);padding:8px 7px 6px}
.toc-list>li.cur a.t{display:flex;align-items:center;min-height:44px;color:#fff;text-decoration:none}
.toc-list>li.cur a.t:hover{text-decoration:underline;text-underline-offset:4px}
.toc-list>li.cur>.n{align-self:center}
.toc-list>li.cur .cnt{grid-column:2;color:var(--baby3)}
.steps{grid-column:1/-1;margin-top:6px}
.steps a{display:flex;align-items:center;gap:10px;min-height:44px;padding:0 8px;border-radius:9px;text-decoration:none;color:#fff;font-size:.95rem}
.steps a:hover{background:rgba(137,207,240,.14)}
.steps li.here>a{background:rgba(137,207,240,.12);box-shadow:inset 2px 0 0 var(--baby)}
.steps .mono{margin-left:auto;color:var(--softd);white-space:nowrap}
.tick{position:relative;width:20px;height:20px;flex:none;border-radius:50%;border:1.5px solid rgba(137,207,240,.7)}
.tick svg{position:absolute;inset:2px;width:13px;height:13px;color:var(--deep);opacity:0}
.done>a .tick,.tick.on{background:var(--baby);border-color:var(--baby)}
.done>a .tick svg,.tick.on svg{opacity:1}
@media (max-width:1000px){
  .lp{grid-template-columns:minmax(0,1fr);padding-left:0;padding-right:0;gap:12px}
  .toc{position:static;max-height:none;overflow:visible;margin:0 var(--pad)}
  .toc-btn{display:flex;align-items:center;gap:12px;width:100%;min-height:60px;padding:8px 14px;background:none;border:0;border-radius:18px;color:#fff;text-align:left;cursor:pointer}
  .toc-btn .tt{display:grid;min-width:0}
  .toc-btn .tt .mono{color:var(--baby)}
  .toc-btn .tt b{font-weight:700;line-height:1.25}
  .toc-btn .cnt{margin-left:auto;color:var(--baby3);white-space:nowrap}
  .toc-btn .chev{width:18px;height:18px;flex:none;transition:transform .2s}
  .toc-btn[aria-expanded=true] .chev{transform:rotate(180deg)}
  .js .toc:not(.open) .toc-panel{display:none}
  .toc-panel{padding-top:4px;border-top:1px solid rgba(137,207,240,.18)}
  html:not(.js) .toc-btn{display:none}
}

/* ---- lesson head + video ---- */
.lhead{padding:clamp(6px,1.4vw,14px) 0 2px}
.lhead .kick{display:flex;flex-wrap:wrap;gap:4px 16px;color:var(--softd)}
.lhead .kick span:first-child{color:var(--baby)}
.lhead h1{margin-top:10px;font-size:clamp(2rem,4.6vw,3.5rem);line-height:1.02;letter-spacing:-.025em;font-weight:820;font-stretch:110%;text-wrap:balance}
.lhead h1 em{font-weight:330;font-stretch:92%;color:var(--baby3)}
.vid{position:relative;border-radius:18px;overflow:hidden;border:1px solid rgba(137,207,240,.3);background:var(--navy)}
.vframe{position:relative;aspect-ratio:16/9;background:#050d20}
.vframe>img,.vframe>video{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.vframe>video{background:#050d20}
.vid.no-video video{display:none}
.vid.has-video .vnote{display:none}
/* with JavaScript the cover (frame 0) lies over the player until it plays; without it the player shows from the start */
.js .vid.has-video .vframe>img{z-index:1}
html:not(.js) .vid.has-video .vframe>img,.vid.has-video.playing .vframe>img{display:none}
.vplay{display:none;position:absolute;inset:0;z-index:2;width:100%;place-content:center;justify-items:center;gap:14px;padding:0;border:0;color:#fff;cursor:pointer;
  background:radial-gradient(circle clamp(90px,13vw,170px) at 50% 50%,rgba(7,20,48,.6),rgba(7,20,48,0))}
.js .vid.has-video:not(.playing) .vplay{display:grid}
.vp-b{position:relative;display:grid;place-items:center;width:clamp(64px,8vw,92px);aspect-ratio:1;border-radius:50%;background:var(--baby);color:var(--deep);box-shadow:0 14px 40px rgba(3,10,26,.6);transition:transform .2s cubic-bezier(.2,.7,.2,1),background .15s}
.vp-b svg{width:42%;height:42%;margin-left:6%}
.vp-b::before{content:"";position:absolute;inset:-11px;border-radius:50%;border:1.5px dashed rgba(137,207,240,.85);animation:spin 18s linear infinite}
.vp-t{display:inline-flex;align-items:center;gap:10px;padding:5px 13px;border-radius:999px;background:rgba(7,20,48,.92);border:1px solid rgba(137,207,240,.45);color:#fff}
.vp-t b{font-weight:600}
.vp-t i{font-style:normal;color:var(--baby3)}
.vplay:hover .vp-b{background:#fff;transform:scale(1.06)}
.vplay:focus-visible{outline-offset:-8px}
.vid.wait .vplay{pointer-events:none}
.vid.wait .vp-b::before{animation-duration:1.2s}
@keyframes spin{to{transform:rotate(360deg)}}
.vnote{position:absolute;z-index:3;right:clamp(10px,2vw,20px);bottom:clamp(10px,2vw,20px);display:inline-flex;align-items:center;gap:8px;padding:6px 12px;border-radius:999px;background:rgba(7,20,48,.92);border:1px solid rgba(137,207,240,.45);color:#fff}
.vnote::before{content:"";width:7px;height:7px;border-radius:50%;background:var(--baby)}
/* under the picture: what it is, the caption being spoken, captions on/off */
.vbar{display:grid;grid-template-columns:auto minmax(0,1fr) auto;align-items:center;gap:6px 18px;min-height:68px;padding:10px clamp(12px,2vw,20px);border-top:1px solid rgba(137,207,240,.22)}
.vlab{color:var(--baby);white-space:nowrap}
.vcap{display:flex;align-items:center;justify-content:center;min-height:3.1em;text-align:center;font-size:1.04rem;line-height:1.5;font-weight:520;color:#fff;text-wrap:balance}
.vcap .idle{font-family:var(--mono);font-stretch:87.5%;font-size:12.5px;font-weight:400;color:var(--softd)}
.vcc{display:none;align-items:center;gap:8px;min-height:44px;padding:0 14px;border-radius:999px;border:1px solid rgba(137,207,240,.55);background:transparent;color:#fff;white-space:nowrap;cursor:pointer}
.js .vid.has-video .vcc{display:inline-flex}
.vcc svg{width:20px;height:20px;color:var(--baby)}
.vcc b{font-weight:600;color:var(--baby3)}
.vcc.off{border-style:dashed}
.vcc.off b{color:var(--softd)}
.vcc:hover{background:rgba(137,207,240,.14)}
@media (max-width:620px){
  .vbar{grid-template-columns:minmax(0,1fr) auto;min-height:0}
  .vcap{grid-column:1/-1;grid-row:2;justify-content:flex-start;text-align:left;min-height:4.6em;align-items:flex-start;font-size:1rem}
}
@media (max-width:1000px){.lhead,.vid,.next{margin:0 var(--pad)}}

/* ---- reading ---- */
.sheet{border-radius:clamp(18px,3vw,28px);padding:clamp(26px,4.4vw,56px) clamp(20px,4.6vw,60px)}
@media (max-width:1000px){.sheet{border-radius:22px 22px 0 0;margin-top:6px}.sheet+.sheet,.ex+.sheet{margin-top:0}}
.read .lab{color:var(--blue)}
.read{font-size:clamp(1.06rem,1.25vw,1.14rem);line-height:1.68}
.rs{display:grid;grid-template-columns:minmax(0,664px) minmax(0,1fr);gap:0 clamp(20px,2.4vw,34px);margin-top:clamp(30px,4vw,48px)}
.rs:first-of-type{margin-top:18px}
.rs>*{grid-column:1}
.rs>.m-art{grid-column:2;grid-row:1/span 3;align-self:start;justify-self:end;width:100%;max-width:170px;height:auto;aspect-ratio:var(--ar);margin-top:26px;color:var(--blue)}
@media (min-width:1181px){.read.sheet{padding-right:clamp(20px,2.6vw,36px)}}
@media (max-width:1180px){.rs{grid-template-columns:minmax(0,664px)}.rs>.m-art{display:none}}
.rs h2{display:grid;grid-template-columns:44px minmax(0,1fr);align-items:baseline;padding-top:18px;border-top:1px solid var(--rule);font-size:clamp(1.4rem,2.4vw,1.75rem);line-height:1.15;letter-spacing:-.012em;font-weight:800;font-stretch:107%;text-wrap:balance}
.rs h2 .mono{color:var(--blue);font-weight:500}
.rs h3{margin-top:22px;font-size:1.15rem;font-weight:750}
.rs p{margin-top:16px}
.rs:first-of-type>p:first-of-type{font-size:1.24em;line-height:1.42;font-weight:560;letter-spacing:-.008em;color:var(--ink);text-wrap:balance}
.cont{display:flex;flex-wrap:wrap;align-items:center;gap:12px 20px;max-width:664px;margin-top:clamp(30px,4vw,48px);padding-top:22px;border-top:1px solid var(--rule)}
.cont .mono{color:var(--blue)}
.cont .btn{margin-left:auto}
.rs p,.rs li,.rs dd{color:#12284f}
.rs strong,.rs dt{color:var(--ink);font-weight:750}
.rs code{font-family:var(--mono);font-stretch:87.5%;font-size:.86em;background:var(--tint);padding:1px 5px;border-radius:5px}
.rs a{color:var(--blue);text-underline-offset:3px}
.rs ul{margin-top:14px;display:grid;gap:10px}
.rs ul li{position:relative;padding-left:26px}
.rs ul li::before{content:"";position:absolute;left:4px;top:.62em;width:8px;height:8px;background:var(--blue);transform:rotate(45deg)}
/* a numbered list is a sequence: mono numerals on the baby-blue thread */
.rs ol{counter-reset:s;position:relative;margin-top:18px;display:grid;gap:12px}
.rs ol li{counter-increment:s;position:relative;min-height:36px;padding:5px 0 5px 52px}
.rs ol li:not(:last-child)::after{content:"";position:absolute;left:17px;top:40px;bottom:-16px;width:2px;background:var(--baby)}
.rs ol li::before{content:counter(s);position:absolute;left:0;top:0;width:36px;height:36px;border-radius:50%;display:grid;place-items:center;background:var(--navy);color:#fff;font-family:var(--mono);font-stretch:87.5%;font-size:13px;font-weight:600}
/* term lists: definition lists */
.rs dl{margin-top:16px;border-top:1px solid var(--rule)}
.rs dl>div{display:grid;grid-template-columns:minmax(0,11.5em) minmax(0,1fr);gap:2px 20px;padding:12px 0;border-bottom:1px solid var(--rule)}
.rs dd{line-height:1.6}
.rs dl.gloss{border:1px solid #cfe0ef;border-radius:16px;background:var(--tint);padding:4px clamp(14px,2.4vw,22px)}
.rs dl.gloss>div{border-bottom:1px dashed #b9cde2}
.rs dl.gloss>div:last-child{border-bottom:0}
.rs dl.gloss dt{font-family:var(--mono);font-stretch:87.5%;font-size:.8em;line-height:2;font-weight:600;color:var(--blue)}
.rs dl.tl{border-top:0;position:relative;margin-top:20px;padding-left:22px}
.rs dl.tl::before{content:"";position:absolute;left:4px;top:8px;bottom:8px;width:2px;background:var(--baby)}
.rs dl.tl>div{position:relative;grid-template-columns:minmax(0,1fr);border-bottom:0;padding:8px 0}
.rs dl.tl>div::before{content:"";position:absolute;left:-23px;top:15px;width:12px;height:12px;background:#fff;border:2px solid var(--blue);transform:rotate(45deg)}
.rs dl.tl dt{font-family:var(--mono);font-stretch:87.5%;font-size:.82em;font-weight:600;color:var(--blue)}
@media (max-width:620px){.rs dl>div{grid-template-columns:minmax(0,1fr)}.rs h2{grid-template-columns:38px minmax(0,1fr)}}
.rfig{grid-column:1/-1;margin:clamp(30px,4vw,48px) 0 0;border-radius:16px;overflow:hidden;background:var(--navy)}
.rfig img{width:100%;height:auto;aspect-ratio:1536/600;object-fit:cover}
#read-end{height:1px}

/* ---- exercise: sticky notes sorted onto two trays, in the drag-in language (dashed frame, handles, W x H, the hand) ---- */
.ex{position:relative;border-radius:clamp(18px,3vw,28px);padding:clamp(26px,4.4vw,52px) clamp(16px,4vw,52px);background:linear-gradient(180deg,var(--navy),#081a3c);border:1px solid rgba(137,207,240,.24)}
.ex::before{content:"";position:absolute;inset:0;border-radius:inherit;pointer-events:none;background:linear-gradient(rgba(137,207,240,.06) 1px,transparent 1px) 0 0/100% 44px,linear-gradient(90deg,rgba(137,207,240,.06) 1px,transparent 1px) 0 0/44px 100%;-webkit-mask-image:linear-gradient(180deg,#000,transparent 70%);mask-image:linear-gradient(180deg,#000,transparent 70%)}
.ex>*{position:relative}
.ex .head{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:0 20px;align-items:end}
.ex .head>*{grid-column:1}
.ex .head .la{grid-column:2;grid-row:1/span 3;height:72px;width:auto;aspect-ratio:var(--ar);color:var(--baby)}
@media (max-width:620px){.ex .head .la{display:none}}
@media (max-width:1000px){.ex{border-radius:0;border-left:0;border-right:0}}
.ex-help{margin-top:10px;color:var(--softd);max-width:70ch}
@media (hover:none) and (pointer:coarse){.ex-help .kb{display:none}}
.board{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.08fr) minmax(0,1fr);gap:14px;margin-top:22px;align-items:stretch}
.bin{position:relative;grid-row:1;min-height:230px;padding:12px;border-radius:14px;border:1.5px dashed rgba(137,207,240,.6);background:rgba(7,20,48,.55);cursor:default;transition:background .15s,border-color .15s}
.bin[data-k="0"]{grid-column:1}.bin[data-k="1"]{grid-column:3}
.bin h3{font-size:1.05rem;line-height:1.25;font-weight:780;color:#fff}
.bin .cnt{display:block;color:var(--baby)}
.bin .hint{margin-top:10px;color:var(--softd)}
.bin.over{border-style:solid;border-color:var(--baby);background:rgba(137,207,240,.16)}
.ex.holding .bin{border-color:var(--baby)}
/* the verdict on a drop, on the side it landed on: colour, a stamp on the top edge, the count ticking */
.bin.yes{border-style:solid;border-color:var(--ok-d);background:rgba(126,226,184,.15)}
.bin.nope{border-style:solid;border-color:var(--no-d);background:rgba(255,180,138,.13)}
.board.done .bin{border-style:solid;border-color:rgba(126,226,184,.75)}
.bin .stamp{visibility:hidden;position:absolute;z-index:4;right:10px;top:-24px;display:inline-flex;align-items:center;gap:7px;height:32px;padding:0 13px 0 10px;border-radius:999px;font-size:13.5px;font-weight:700;white-space:nowrap;pointer-events:none;box-shadow:0 6px 16px rgba(3,10,26,.45)}
.bin .stamp svg{width:17px;height:17px;stroke-width:2.8}
.bin.yes .stamp{visibility:visible;background:var(--ok-d);color:var(--deep);animation:stamp .26s cubic-bezier(.2,1.5,.4,1)}
.bin.nope .stamp{visibility:visible;background:var(--no-d);color:var(--no-dk);animation:stamp .26s cubic-bezier(.2,1.5,.4,1)}
@keyframes stamp{from{transform:translateY(8px) scale(.7)}}
.bin .cnt{transform-origin:0 50%}
.bin .cnt.bumped{animation:bumped .55s cubic-bezier(.2,.7,.2,1)}
@keyframes bumped{30%{transform:scale(1.3);color:var(--ok-d)}}
.bin ul{display:grid;gap:8px;margin-top:10px}
.bin ul:empty{display:none}
.bin li{position:relative;display:grid;grid-template-columns:22px minmax(0,1fr);gap:9px;padding:9px 10px;border-radius:8px;background:var(--ok-bg);color:var(--ink);font-size:.93rem;line-height:1.35;font-weight:550;box-shadow:0 0 0 1.5px var(--ok) inset}
.bin li .mk{background:var(--ok);color:#fff}
.bin li .mono{grid-column:2;color:var(--ink2);font-size:11.5px}
.bin li.new{animation:glow .8s ease-out}
@keyframes glow{from{box-shadow:0 0 0 1.5px var(--ok) inset,0 0 0 0 rgba(126,226,184,.9)}to{box-shadow:0 0 0 1.5px var(--ok) inset,0 0 0 16px rgba(126,226,184,0)}}
.mid{grid-column:2;grid-row:1;min-width:0}
.pile{display:grid;gap:10px}
.slot{position:relative;min-width:0}
.card{position:relative;display:grid;grid-template-columns:18px minmax(0,1fr);gap:9px;align-items:start;width:100%;min-height:52px;padding:13px 12px 13px 10px;border:0;border-radius:8px;background:var(--note);color:var(--ink);text-align:left;font-size:.98rem;line-height:1.35;font-weight:550;cursor:grab;
  box-shadow:0 1px 0 rgba(255,255,255,.5) inset,0 8px 18px rgba(3,10,26,.35);touch-action:none;-webkit-user-select:none;user-select:none;-webkit-touch-callout:none;-webkit-tap-highlight-color:transparent}
.card .grip{width:18px;height:18px;margin-top:2px;color:#4b6a94}
.card .why{grid-column:2;display:none;margin-top:5px;font-size:.84rem;line-height:1.35;color:var(--no-ink);font-weight:550}
.card .why b{font-weight:800}
.card .xb{display:none}
/* a card that was dropped on the wrong side: rust frame on warm paper, a cross on its corner, a note saying which kind it is */
.card.miss .why{display:block}
.card.miss{background:var(--no-bg);box-shadow:0 0 0 2px var(--no) inset,0 8px 18px rgba(3,10,26,.35)}
.card.miss .xb{position:absolute;right:-8px;top:-10px;display:grid;place-items:center;width:28px;height:28px;border-radius:50%;background:var(--no);color:#fff;box-shadow:0 0 0 2.5px var(--navy)}
.card.miss .xb svg{width:15px;height:15px;stroke-width:2.8}
.card.shake{animation:shake .5s cubic-bezier(.36,.07,.19,.97)}
.card.busy{z-index:29;pointer-events:none}
@keyframes shake{10%,90%{translate:-2px 0}20%,80%{translate:5px 0}30%,50%,70%{translate:-9px 0}40%,60%{translate:9px 0}}
.card:focus-visible{outline:2px solid #fff;outline-offset:3px}
.card.held{z-index:30;cursor:grabbing;background:#e9f6fe;box-shadow:0 26px 60px rgba(3,10,26,.55)}
.card.back{transition:transform .3s cubic-bezier(.2,.7,.2,1)}
.card.float{transition:transform .2s cubic-bezier(.2,.7,.2,1)}
html.ex-drag,html.ex-drag *{cursor:grabbing!important}
html.ex-hide,html.ex-hide *{cursor:none!important}
/* the selection rig: put on the held card, and for a moment on the note that was just dropped */
.rig{position:absolute;inset:-5px;pointer-events:none;border:1.5px dashed var(--baby);border-radius:11px;z-index:2}
.rig.dropped{border-style:solid}
.rig i{position:absolute;width:8px;height:8px;background:#fff;border:1.5px solid var(--baby)}
.rig .a{left:-4px;top:-4px}.rig .b{right:-4px;top:-4px}.rig .c{left:-4px;bottom:-4px}.rig .d{right:-4px;bottom:-4px}
.rig .tg,.rig .sz{position:absolute;font:600 10px/1 var(--mono);font-stretch:87.5%;letter-spacing:.04em;padding:4px 7px;white-space:nowrap}
.rig .tg{left:-1.5px;bottom:100%;margin-bottom:4px;background:var(--deep);color:#fff}
.rig .sz{top:100%;left:50%;transform:translateX(-50%);margin-top:5px;background:var(--baby);color:var(--deep);font-variant-numeric:tabular-nums}
.rig .cur{position:absolute;right:-5px;top:-11px;width:30px;height:30px}
.rig .cur svg{position:absolute;inset:0;width:30px;height:30px;filter:drop-shadow(0 2px 3px rgba(3,10,26,.5))}
.rig .cur .arrow{opacity:0}.rig.dropped .cur .arrow{opacity:1}.rig.dropped .cur .hand{opacity:0}
.rig.out{opacity:0;transition:opacity .22s}
.rig.ok{border-style:solid;border-color:var(--ok-d)}
.rig.ok i{border-color:var(--ok-d)}
.rig.ok .sz,.rig.ok .cur{display:none}
.rig.ok .tg{background:var(--ok-d);color:var(--deep)}
.bin li .rig .tg{display:none}
.light .rig.ok,.light .rig.ok i{border-color:var(--ok)}
.light .rig.ok .tg{background:var(--ok);color:#fff}
/* the line under the board: the verdict on the last drop and the reason; its room is kept, so nothing moves */
.ex-say{display:grid;grid-template-columns:auto minmax(0,1fr);gap:12px;align-items:start;min-height:76px;margin-top:16px;padding:13px 16px;border-radius:14px;border:1.5px solid rgba(137,207,240,.3);background:rgba(7,20,48,.62);color:#fff}
.ex-say .mk{width:30px;height:30px;border:1.5px dashed rgba(137,207,240,.65)}
.ex-say p{font-size:.98rem;line-height:1.45;color:#e9f0fb}
.ex-say b{font-weight:800;color:#fff}
.ex-say.ok{border-color:var(--ok-d);background:rgba(126,226,184,.1)}
.ex-say.ok .mk{border:0;background:var(--ok-d);color:var(--deep)}
.ex-say.ok b{color:var(--ok-d)}
.ex-say.no{border-color:var(--no-d);background:rgba(255,180,138,.09)}
.ex-say.no .mk{border:0;background:var(--no-d);color:var(--no-dk)}
.ex-say.no b{color:var(--no-d)}
.ex-say.bump{animation:bump .32s cubic-bezier(.2,.7,.2,1)}
@keyframes bump{from{transform:scale(.985)}55%{transform:scale(1.012)}}
.ex-foot{display:flex;flex-wrap:wrap;align-items:center;gap:10px 16px;margin-top:16px}
.pips{display:flex;gap:5px}
.pips li{width:24px;height:8px;border-radius:4px;background:rgba(137,207,240,.24);transition:background .25s}
.pips li.on{background:var(--ok-d)}
.ex-foot .stat{color:#fff;font-size:13.5px}
.ex-foot .stat b{font-weight:600}
.ex-foot .stat .ms{color:var(--no-d)}
.ex-foot .stat .was{color:var(--softd)}
.snd{display:inline-flex;align-items:center;gap:8px;min-height:44px;margin-left:auto;padding:0 14px;border-radius:999px;border:1px solid rgba(137,207,240,.45);background:transparent;color:#fff;white-space:nowrap;cursor:pointer}
.snd svg{width:19px;height:19px;color:var(--baby)}
.snd:not(.on) .w{display:none}
.snd b{font-weight:600;color:var(--softd)}
.snd.on b{color:var(--ok-d)}
.snd:hover{background:rgba(137,207,240,.14)}
.snd[hidden]+.btn{margin-left:auto}
.ex-done{position:relative;padding:20px 20px 22px;border-radius:14px;background:var(--note);color:var(--ink)}
.ex-done:focus{outline:none}
.ex-done:focus-visible{outline:2px solid #fff;outline-offset:3px}
.ex-done .ok{width:56px;height:56px;color:var(--ok)}
.ex-done .ok circle,.ex-done .ok path{stroke-dasharray:1}
.ex-done.go .ok circle{animation:draw .6s cubic-bezier(.3,.6,.2,1) both}
.ex-done.go .ok path{animation:draw .35s .5s cubic-bezier(.3,.6,.2,1) both}
@keyframes draw{from{stroke-dashoffset:1}}
.ln{display:block;width:64px;height:2px;margin:10px 0 12px;background:var(--blue);transform-origin:0 50%}
.go>.ln,.go .res-t .ln{animation:grow .5s .65s cubic-bezier(.3,.6,.2,1) both}
@keyframes grow{from{transform:scaleX(0)}}
.ex-done b{display:block;margin:10px 0 0;font-size:1.4rem;line-height:1.12;font-weight:820;font-stretch:108%}
.ex-done p{font-size:.98rem;line-height:1.5;color:#12284f}
.ex-done .mono{margin-top:10px;font-size:13px;color:var(--ok);font-weight:600}
.ex-done .btn{margin-top:16px;background:var(--ink);border-color:var(--ink);color:#fff}
.ex-done .btn:hover{background:var(--navy2);border-color:var(--navy2)}
.ex-done .btn:focus-visible{outline-color:var(--ink)}
@media (max-width:760px){
  .board{grid-template-columns:repeat(2,minmax(0,1fr));gap:18px 10px}
  .pile{gap:10px}
  .mid{grid-column:1/-1;grid-row:1}
  .pile{grid-template-columns:repeat(2,minmax(0,1fr));align-items:stretch}
  .card{height:100%;align-content:start}
  .bin{grid-row:2;min-height:150px;padding:10px}
  .bin[data-k="0"]{grid-column:1}.bin[data-k="1"]{grid-column:2}
  .card{font-size:.92rem;padding:11px 9px 11px 7px;gap:6px;grid-template-columns:16px minmax(0,1fr)}
  .card .grip{width:16px;height:16px}
  .bin h3{font-size:.98rem}
  .bin li{font-size:.86rem;grid-template-columns:20px minmax(0,1fr);gap:7px;padding:8px}
  .bin li .mk{width:20px;height:20px}
  .bin .stamp{right:8px;font-size:13px;padding:0 11px 0 8px}
  .ex-say{min-height:104px}
  /* on a phone the verdict stays in sight under the thumb while the board is on screen */
  .ex-say.ok,.ex-say.no{position:sticky;bottom:10px;z-index:20;box-shadow:0 10px 30px rgba(3,10,26,.6)}
  .ex-say.ok{background:#0f2f48}.ex-say.no{background:#1f2440}
  .snd{margin-left:0}
  .ex-foot .btn{margin-left:auto}
}

/* ---- quiz ---- */
.quiz .head{max-width:680px}
.q-top{display:flex;flex-wrap:wrap;align-items:center;gap:10px 16px;margin-top:24px;max-width:680px}
.q-top .mono{color:var(--blue)}
.q-dots{display:flex;gap:6px;margin-left:auto}
.q-dots li{width:26px;height:6px;border-radius:3px;background:#cfdcec}
.q-dots li.cur{background:var(--blue)}
.q-dots li.right{background:var(--ok)}
.q-dots li.wrong{background:repeating-linear-gradient(135deg,var(--no) 0 3px,#f6d3c2 3px 6px)}
.q-best{margin-top:14px;max-width:680px;padding:10px 14px;border-radius:12px;background:var(--tint);border:1px solid #cfe0ef;color:var(--ink)}
.q{max-width:680px;margin-top:14px}
.js .q[data-later]{display:none}
.q legend{display:grid;grid-template-columns:44px minmax(0,1fr);align-items:baseline;width:100%;font-size:clamp(1.25rem,2.2vw,1.5rem);line-height:1.25;font-weight:780;font-stretch:105%;color:var(--ink)}
.q legend:focus{outline:none}
.q legend .mono{color:var(--blue);font-weight:500}
.opts{display:grid;gap:10px;margin-top:18px}
.opt{position:relative;display:block;cursor:pointer}
.opt input{position:absolute;opacity:0;width:100%;height:100%;inset:0;margin:0;cursor:pointer}
.opt-b{display:grid;grid-template-columns:30px minmax(0,1fr) auto;gap:12px;align-items:center;min-height:56px;padding:11px 14px;border-radius:14px;border:1.5px solid #8fa6c4;background:#fff;color:var(--ink);line-height:1.4}
.opt-k{display:grid;place-items:center;width:30px;height:30px;border-radius:8px;border:1.5px solid #8fa6c4;color:var(--blue);font-weight:600}
.opt-m{display:none;align-items:center;gap:7px;white-space:nowrap;font-weight:600}
.opt:hover .opt-b{border-color:var(--blue);background:var(--tint)}
.opt input:checked+.opt-b{border-color:var(--ink);background:var(--tint);box-shadow:0 0 0 1.5px var(--ink) inset}
.opt input:checked+.opt-b .opt-k{background:var(--ink);border-color:var(--ink);color:#fff}
.opt input:focus-visible+.opt-b{outline:2px solid var(--ink);outline-offset:3px}
.q.locked .opt,.q.locked .opt input{cursor:default}
.q.locked .opt:hover .opt-b{background:#fff;border-color:#8fa6c4}
.q.locked .opt:not(.is-right):not(.is-wrong) .opt-b{border-color:#c5d3e4;color:var(--soft);box-shadow:none;background:#fff}
.q.locked .opt:not(.is-right):not(.is-wrong) .opt-k{border-color:#c5d3e4;background:#fff;color:var(--soft)}
/* the same right and wrong as the exercise: green with a check, rust with a cross */
.q.locked .opt.is-right .opt-b,.q.locked .opt.is-right:hover .opt-b{border-color:var(--ok);background:var(--ok-bg);color:var(--ink);box-shadow:0 0 0 1.5px var(--ok) inset;animation:pop .36s cubic-bezier(.2,.7,.2,1)}
.q.locked .opt.is-right .opt-k{background:var(--ok);border-color:var(--ok);color:#fff}
.q.locked .opt.is-right .opt-m{color:var(--ok)}
.q.locked .opt.is-right .opt-m .mk{background:var(--ok);color:#fff}
.q.locked .opt.is-wrong .opt-b,.q.locked .opt.is-wrong:hover .opt-b{border-color:var(--no);background:var(--no-bg);color:var(--ink);box-shadow:0 0 0 1.5px var(--no) inset;animation:shake .45s cubic-bezier(.36,.07,.19,.97)}
.q.locked .opt.is-wrong .opt-k{background:var(--no);border-color:var(--no);color:#fff}
.q.locked .opt.is-wrong .opt-m{color:var(--no-ink)}
.q.locked .opt.is-wrong .opt-m .mk{background:var(--no);color:#fff}
@keyframes pop{from{transform:scale(.985)}55%{transform:scale(1.015)}}
.q.locked .opt.is-right .opt-m,.q.locked .opt.is-wrong .opt-m{display:inline-flex}
@media (max-width:520px){.opt-b{grid-template-columns:30px minmax(0,1fr)}.opt-m{grid-column:2}}
.q-fb{display:grid;grid-template-columns:auto minmax(0,1fr);gap:2px 12px;margin-top:16px;padding:14px 16px;border-radius:14px;background:var(--tint);border:1px solid #cfe0ef;border-left:4px solid var(--blue);color:var(--ink)}
.q-fb:focus{outline:none}
.q-fb .mk{grid-row:1/span 2;width:30px;height:30px;margin-top:1px}
.q-fb b{display:block;align-self:center;font-size:1.12rem;font-weight:800}
.q-fb p{grid-column:2;line-height:1.55;color:#12284f}
.q-fb.ok{background:var(--ok-bg);border-color:#b3e2c9;border-left-color:var(--ok)}
.q-fb.ok .mk{background:var(--ok);color:#fff}
.q-fb.ok b{color:var(--ok)}
.q-fb.no{background:var(--no-bg);border-color:#f2cdb8;border-left-color:var(--no)}
.q-fb.no .mk{background:var(--no);color:#fff}
.q-fb.no b{color:var(--no-ink)}
.q-act{display:flex;flex-wrap:wrap;align-items:center;gap:10px 16px;margin-top:20px;max-width:680px}
.q-msg{color:var(--no-ink);font-weight:600}
.q-msg:empty{display:none}
.q-res{position:relative;max-width:680px;margin-top:22px;padding:clamp(20px,3vw,32px);border-radius:20px;background:var(--navy);color:#fff}
.q-res:focus{outline:none}
.res-top{display:grid;grid-template-columns:auto minmax(0,1fr);gap:clamp(16px,3vw,30px);align-items:center}
.ring{position:relative;display:grid;place-items:center;width:clamp(104px,27vw,136px);aspect-ratio:1}
.ring svg{position:absolute;inset:0;width:100%;height:100%}
.ring .tr{stroke:rgba(137,207,240,.2);stroke-width:8}
.ring .pr{stroke:var(--baby);stroke-width:8;stroke-linecap:round;stroke-dasharray:1 1;stroke-dashoffset:1}
.q-res.go .pr{transition:stroke-dashoffset 1s cubic-bezier(.2,.7,.2,1)}
.q-res.pass .pr{stroke:var(--ok-d)}
.q-res.fail .pr{stroke:var(--no-d)}
.ring b{position:relative;font-family:var(--mono);font-stretch:87.5%;font-size:clamp(1.55rem,5.4vw,2rem);line-height:1;font-weight:600;letter-spacing:-.03em;white-space:nowrap}
.res-t .mono{color:var(--baby3)}
.q-res h3{display:flex;align-items:center;gap:10px;margin-top:6px;font-size:clamp(1.6rem,3.4vw,2.2rem);line-height:1.1;font-weight:820;font-stretch:108%}
.q-res h3 .mk{width:.95em;height:.95em}
.q-res.pass h3 .mk{background:var(--ok-d);color:var(--deep)}
.q-res.fail h3 .mk{background:var(--no-d);color:var(--no-dk)}
.q-res .ln{margin:12px 0 0;background:var(--baby)}
.q-res p{color:#dbe7f8}
.q-res #q-next{margin-top:16px;max-width:52ch}
.q-res h3 .mk{margin-top:.08em;align-self:flex-start}
.q-res .ring{margin-top:0}
.q-res .rev{display:grid;gap:8px;margin-top:18px;padding-top:16px;border-top:1px solid rgba(137,207,240,.25)}
.q-res .rev li{display:grid;grid-template-columns:22px minmax(0,1fr);gap:9px;color:#fff;font-size:.95rem;line-height:1.4}
.q-res .rev .mk{width:20px;height:20px;margin-top:1px;background:rgba(126,226,184,.2);color:var(--ok-d)}
.q-res .rev .no{color:#dbe7f8}
.q-res .rev .no .mk{background:rgba(255,180,138,.18);color:var(--no-d)}
@media (max-width:520px){.q-res h3{font-size:1.4rem}.ring{width:96px}}
.q-res .rig.ok,.q-res .rig.ok i{border-color:var(--ok)}
.q-res .rig.ok .tg{background:var(--ok);color:#fff}
.q-res .btn,.deal .box .btn{margin-top:18px;background:var(--baby);border-color:var(--baby);color:var(--deep)}
.q-res .btn:hover,.deal .box .btn:hover{background:#fff;border-color:#fff}
.q-res :focus-visible{outline-color:var(--baby)}
.noscript{margin-top:16px;padding:12px 14px;border:1px dashed var(--blue);border-radius:12px;background:#f5f9fd;color:var(--ink);max-width:680px}

/* ---- next lesson ---- */
.next{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:6px 18px;align-items:center;padding:18px clamp(16px,3vw,26px);border-radius:18px;border:1px solid rgba(137,207,240,.26);background:var(--navy)}
.next .mono{color:var(--baby)}
.next b{display:block;font-size:1.2rem;line-height:1.25;font-weight:780}
.next .st{grid-column:1;display:flex;align-items:flex-start;gap:7px;color:var(--softd)}
.next .st svg{width:14px;height:14px;margin-top:3px;flex:none}
.next .lk{grid-row:1/span 3;grid-column:2;display:grid;place-items:center;width:52px;height:52px;border-radius:50%;border:1.5px dashed rgba(137,207,240,.6);color:var(--baby)}
.next .lk svg{width:22px;height:22px}
.next.open .lk{border-style:solid;background:rgba(137,207,240,.14)}

@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{transition:none!important;animation:none!important;scroll-behavior:auto!important}
}
@media print{.toc,.cbar .chip,.ex,.quiz,.next,.thread,.vid,.cont{display:none}}

/* access pages: "for enrolled learners" (nginx 403 page), the link landing page, and the "lost my link" form */
.lockp h1{font-size:clamp(2.3rem,6.4vw,4.8rem)}
.lockp .sub{max-width:36ch}
.lk-learner{display:flex;flex-wrap:wrap;align-items:center;gap:14px 22px;margin-top:28px;padding-top:22px;border-top:1px solid rgba(137,207,240,.22)}
.lk-learner[hidden]{display:none}
.lk-learner p{flex-basis:100%;color:var(--baby3)}
.lost{max-width:780px}
.lostf{margin-top:24px}
.lostf label{display:block;margin-bottom:8px;color:var(--blue)}
.lost-row{display:flex;flex-wrap:wrap;gap:12px}
.lost-row input{flex:1 1 260px;min-width:0;min-height:50px;padding:12px 14px;border-radius:12px;border:1px solid #8fa6c4;background:#fff;color:var(--ink);font-size:16px;line-height:1.4}
.lost-row input:focus-visible{outline:2px solid var(--blue);outline-offset:2px;border-color:var(--blue)}
.lost-row input[aria-invalid=true]{border-color:var(--no)}
.lost-row .btn[disabled]{opacity:.65;cursor:progress}
.lost-st{min-height:1.6em;margin-top:12px;color:var(--ink)}
.lost .quiet{margin-top:20px;color:var(--soft)}
.lost .quiet a{display:inline-flex;align-items:center;min-height:44px;color:var(--blue);text-underline-offset:3px}