:root{
    --bg:hsl(220 16% 98%); --bg-2:hsl(0 0% 100%); --ink:hsl(228 32% 14%);
    --ink-soft:hsl(228 14% 36%); --ink-faint:hsl(228 10% 52%); --line:hsl(220 15% 89%);
    --hot-ink:hsl(28 82% 40%); --cool-ink:hsl(212 55% 42%);
    --shadow:0 1px 2px hsl(220 20% 30% / .05), 0 8px 22px hsl(220 20% 30% / .05);
    --st-bg1:hsl(232 46% 7%); --st-bg2:hsl(234 40% 12%); --st-grid:hsl(228 40% 60% / .06);
    --st-line:hsl(228 22% 24%); --st-label:hsl(220 17% 75%);
    --st-tok-bg:hsl(228 32% 15%); --st-tok-bg2:hsl(228 32% 18%); --st-tok-ink:hsl(214 24% 96%); --st-tok-line:hsl(228 24% 28%);
    --maxw:68ch;
  }
  @media (prefers-color-scheme: dark){ :root{ --bg:hsl(230 26% 9%); --bg-2:hsl(230 24% 12%); --ink:hsl(220 26% 92%); --ink-soft:hsl(220 14% 70%); --ink-faint:hsl(220 10% 54%); --line:hsl(228 18% 22%); --hot-ink:hsl(36 92% 62%); --cool-ink:hsl(212 62% 68%); --shadow:0 1px 2px hsl(0 0% 0% / .3), 0 16px 40px hsl(0 0% 0% / .35); } }
  :root[data-theme="light"]{ --bg:hsl(220 16% 98%); --bg-2:hsl(0 0% 100%); --ink:hsl(228 32% 14%); --ink-soft:hsl(228 14% 36%); --ink-faint:hsl(228 10% 52%); --line:hsl(220 15% 89%); --hot-ink:hsl(28 82% 40%); --cool-ink:hsl(212 55% 42%); --shadow:0 1px 2px hsl(220 20% 30% / .05), 0 8px 22px hsl(220 20% 30% / .05); }
  :root[data-theme="dark"]{ --bg:hsl(230 26% 9%); --bg-2:hsl(230 24% 12%); --ink:hsl(220 26% 92%); --ink-soft:hsl(220 14% 70%); --ink-faint:hsl(220 10% 54%); --line:hsl(228 18% 22%); --hot-ink:hsl(36 92% 62%); --cool-ink:hsl(212 62% 68%); --shadow:0 1px 2px hsl(0 0% 0% / .3), 0 16px 40px hsl(0 0% 0% / .35); }

  *{box-sizing:border-box} html{-webkit-text-size-adjust:100%}
  body{ margin:0; background:var(--bg); color:var(--ink); font-family:ui-sans-serif,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif; font-size:clamp(17px,1.02rem + .25vw,19px); line-height:1.7; -webkit-font-smoothing:antialiased; text-rendering:optimizeLegibility; }
  .mono{ font-family:ui-monospace,"SF Mono",Menlo,Consolas,monospace; }
  .wrap{ max-width:var(--maxw); margin-inline:auto; padding-inline:22px; } .wide{ max-width:1080px; }
  h1,h2,h3{ font-family:Georgia,"Iowan Old Style","Times New Roman",serif; font-weight:600; line-height:1.14; text-wrap:balance; letter-spacing:-.01em; }
  p{ margin:0 0 1.05em; } a{ color:var(--hot-ink); }
  .eyebrow{ font-family:ui-monospace,Menlo,Consolas,monospace; font-size:.72rem; letter-spacing:.22em; text-transform:uppercase; color:var(--ink-faint); margin:0 0 1.1em; min-height:1em; }
  .lead{ font-size:1.16em; color:var(--ink-soft); }

  .topnav{ position:sticky; top:0; z-index:50; display:flex; align-items:center; justify-content:space-between; gap:14px; padding:10px clamp(16px,4vw,40px); background:var(--bg-2); background:color-mix(in srgb, var(--bg) 78%, transparent); -webkit-backdrop-filter:saturate(1.5) blur(10px); backdrop-filter:saturate(1.5) blur(10px); border-bottom:1px solid var(--line); }
  .brand{ display:inline-flex; align-items:center; gap:.62ch; text-decoration:none; color:var(--ink); font-family:Georgia,serif; font-weight:600; font-size:1.02rem; letter-spacing:-.01em; }
  .brand-mark{ flex:none; width:22px; height:22px; border-radius:7px; background:conic-gradient(from 210deg,hsl(36 92% 56%),hsl(30 88% 48%),hsl(212 62% 55%),hsl(36 92% 56%)); box-shadow:0 0 0 3px hsl(36 92% 55% / .16); }
  .brand small{ color:var(--ink-faint); font-family:ui-monospace,Menlo,monospace; font-weight:400; font-size:.66rem; letter-spacing:.12em; text-transform:uppercase; }
  .nav-actions{ display:flex; align-items:center; gap:9px; position:relative; }
  .toggle,.menu-btn{ display:inline-flex; align-items:center; gap:.5ch; border:1px solid var(--line); background:var(--bg-2); color:var(--ink-soft); border-radius:999px; padding:.45em .85em; font-size:.8rem; cursor:pointer; font-family:ui-monospace,Menlo,monospace; box-shadow:var(--shadow); }
  .toggle:hover,.menu-btn:hover{ color:var(--ink); } .menu-btn[aria-expanded="true"]{ color:var(--ink); border-color:var(--ink-faint); }
  .menu-panel{ position:absolute; right:0; top:calc(100% + 10px); width:min(330px,88vw); background:var(--bg-2); border:1px solid var(--line); border-radius:16px; box-shadow:var(--shadow); padding:8px; display:flex; flex-direction:column; gap:3px; z-index:60; max-height:80vh; overflow:auto; }
  .menu-panel[hidden]{ display:none; }
  .menu-title{ font-family:ui-monospace,Menlo,monospace; font-size:.66rem; letter-spacing:.16em; text-transform:uppercase; color:var(--ink-faint); padding:8px 12px 4px; }
  .menu-part{ display:flex; align-items:baseline; gap:.7ch; flex-wrap:wrap; padding:15px 12px 5px; }
  .menu-part:first-child{ padding-top:8px; }
  .menu-part .mp-n{ font-family:ui-monospace,Menlo,monospace; font-size:.62rem; letter-spacing:.16em; text-transform:uppercase; color:var(--hot-ink); font-weight:600; }
  .menu-part .mp-sub{ font-size:.74rem; color:var(--ink-faint); }
  .menu-item{ display:flex; gap:12px; align-items:center; padding:10px 12px; border-radius:11px; text-decoration:none; color:var(--ink); } .menu-item:hover{ background:var(--bg); }
  .menu-item[aria-current="page"]{ background:color-mix(in srgb, var(--hot-ink) 12%, var(--bg-2)); box-shadow:inset 0 0 0 1px color-mix(in srgb, var(--hot-ink) 40%, transparent); }
  .mi-num{ font-family:ui-monospace,Menlo,monospace; font-size:.72rem; color:var(--hot-ink); font-weight:600; min-width:2ch; }
  .mi-body{ display:flex; flex-direction:column; line-height:1.3; } .mi-body b{ font-size:.95rem; } .mi-body small{ color:var(--ink-faint); font-size:.8rem; }

  header.hero{ padding:clamp(30px,4.5vh,54px) 0 12px; }
  header.hero h1{ font-size:clamp(2rem,1.3rem + 3.2vw,3.4rem); margin:0 0 .5em; } header.hero .lead{ max-width:60ch; }
  header.hero h1 em{ font-style:italic; color:var(--hot-ink); }
  section{ padding:clamp(24px,3.5vh,44px) 0; } section + section{ border-top:1px solid var(--line); }
  .kicker{ font-family:ui-monospace,Menlo,monospace; font-size:.72rem; letter-spacing:.2em; text-transform:uppercase; color:var(--hot-ink); margin-bottom:1em; }
  h2{ font-size:clamp(1.5rem,1.2rem + 1.6vw,2.2rem); margin:0 0 .7em; } h3{ font-size:1.12rem; margin:0 0 .4em; }
  .reveal{ opacity:0; transform:translateY(14px); transition:opacity .7s ease, transform .7s ease; } .reveal.in{ opacity:1; transform:none; }
  @media (prefers-reduced-motion: reduce){ .reveal{opacity:1; transform:none; transition:none} }

  .stage-shell{ position:relative; border-radius:20px; overflow:hidden; background:radial-gradient(120% 90% at 50% -10%, var(--st-bg2), var(--st-bg1) 70%); box-shadow:0 14px 36px hsl(232 50% 6% / .17), inset 0 0 0 1px hsl(228 40% 60% / .08); padding:clamp(16px,3vw,28px); }
  .stage-shell::before{ content:""; position:absolute; inset:0; pointer-events:none; background-image:linear-gradient(var(--st-grid) 1px,transparent 1px),linear-gradient(90deg,var(--st-grid) 1px,transparent 1px); background-size:34px 34px; mask-image:radial-gradient(120% 100% at 50% 30%,#000 55%,transparent 100%); }
  .st-label{ font-family:ui-monospace,Menlo,monospace; font-size:.68rem; letter-spacing:.16em; text-transform:uppercase; color:var(--st-label); }

  .btn{ appearance:none; border:1px solid var(--line); background:var(--bg-2); color:var(--ink); font:inherit; font-size:.9rem; font-weight:500; padding:.55em 1em; border-radius:10px; cursor:pointer; display:inline-flex; align-items:center; gap:.5ch; box-shadow:var(--shadow); transition:transform .12s ease; }
  .btn:hover{ transform:translateY(-1px); } .btn:active{ transform:translateY(0); }
  .btn.ghost{ background:transparent; } .btn:disabled{ opacity:.5; cursor:not-allowed; transform:none; }
  .btn.primary{ background:linear-gradient(hsl(36 92% 56%),hsl(30 88% 50%)); color:hsl(30 60% 12%); border-color:transparent; font-weight:600; }
  /* buttons inside the stage (always-dark background): light text so they do not vanish in light mode */
  .stage-shell .btn.ghost{ color:var(--st-label); border-color:var(--st-line); }
  .stage-shell .btn.ghost:hover{ color:var(--st-tok-ink); border-color:var(--st-tok-line); }
  .btn:focus-visible,.toggle:focus-visible,.menu-btn:focus-visible,.ev:focus-visible{ outline:3px solid var(--hot-ink); outline-offset:2px; }

  .cards{ display:grid; grid-template-columns:repeat(auto-fit,minmax(230px,1fr)); gap:16px; margin-top:1.4em; }
  .card{ background:var(--bg-2); border:1px solid var(--line); border-radius:14px; padding:1.25em 1.3em; box-shadow:none; }
  .card .tag{ font-family:ui-monospace,Menlo,monospace; font-size:.7rem; letter-spacing:.14em; text-transform:uppercase; color:var(--hot-ink); display:block; margin-bottom:.55em; }
  .card p{ margin:0; color:var(--ink-soft); font-size:.95em; } .card h3{ margin-bottom:.35em; }
  /* callout: the section's key point, kept as a deliberate focal moment (warm amber tint + accent) so it draws the eye against the calm near-white page */
  .callout{ margin:1.9em 0; padding:1.15em 1.35em 1.15em 1.4em; border-left:3px solid var(--hot-ink); background:hsl(38 72% 95.5%); border-radius:0 10px 10px 0; box-shadow:none; } .callout p{ margin:0; }
  /* caution variant (sensitive topics): red tint instead of amber */
  .callout.warn{ border-left-color:hsl(6 70% 52%); background:hsl(6 65% 96%); }

  footer{ padding:8px 0 70px; margin-top:-22px; color:var(--ink-faint); font-size:.86rem; }
  /* short amber rule separating the lesson body from the closing thesis (tighter above, airier below) */
  footer .wrap::before{ content:""; display:block; width:48px; height:3px; background:var(--hot-ink); border-radius:2px; margin:0 auto 3.8em; }
  /* closing thesis: an italic pull-quote framed by large amber bookend quote marks (the marks
     replace the inline quotes, which are stripped from the content) */
  footer .thesis{ position:relative; font-family:Georgia,"Iowan Old Style","Times New Roman",serif; font-style:italic; font-size:clamp(1.35rem,1.15rem + .8vw,1.65rem); line-height:1.45; color:var(--ink); text-align:left; max-width:34ch; margin:.3em auto 1.7em; padding-bottom:.15em; }
  footer .thesis::before{ content:"“"; position:absolute; left:-.42em; top:-.3em; font-style:normal; font-family:Georgia,serif; font-size:4.4rem; line-height:1; color:var(--hot-ink); }
  footer .thesis::after{ content:"”"; font-style:normal; font-family:Georgia,serif; font-size:3.8rem; line-height:0; vertical-align:-.24em; color:var(--hot-ink); margin-left:.06em; }
  @media (max-width:560px){ footer .thesis::before{ left:-.34em; font-size:3.6rem; } footer .thesis::after{ font-size:3.1rem; vertical-align:-.22em; } }
  /* pagination: plain text links (no card), centered at a comfortable reading width (shared.js moves
     this block out of .wrap and appends it straight to <footer>, so it carries its own width +
     centering); previous on the left, next on the right, under a hairline */
  .next-lesson{ display:flex; flex-flow:row nowrap; justify-content:space-between; align-items:flex-start; gap:32px; max-width:720px; margin:2.2em auto 1.8em; padding:1.5em 22px 0; border-top:1px solid var(--line); }
  .lesson-link{ display:flex; flex-direction:column; gap:.4em; text-decoration:none; color:var(--ink); flex:1 1 0; min-width:0; }
  .lesson-link.next{ text-align:right; align-items:flex-end; }
  .lesson-link .ll-kick{ font-family:ui-monospace,Menlo,monospace; font-size:.66rem; letter-spacing:.16em; text-transform:uppercase; color:var(--ink-faint); }
  .lesson-link .ll-title{ display:block; line-height:1.22; }
  .lesson-link .ll-num{ font-family:ui-monospace,Menlo,monospace; font-size:.95rem; font-weight:600; color:var(--hot-ink); }
  .lesson-link.prev .ll-num{ margin-right:.15em; } .lesson-link.next .ll-num{ margin-left:.15em; }
  .lesson-link .ll-title b{ font-family:Georgia,serif; font-size:1.12rem; font-weight:600; color:var(--ink); transition:color .16s ease; }
  .lesson-link:hover .ll-title b, .lesson-link:hover .ll-num{ color:var(--hot-ink); }
  @media (max-width:560px){ .next-lesson{ flex-wrap:wrap; gap:18px; } .lesson-link{ flex-basis:100%; } .lesson-link.next{ align-items:flex-start; text-align:left; } }

  /* ---------- Sidebar (desktop) ---------- */
  .sidebar{ display:none; position:fixed; left:0; top:0; bottom:0; width:300px; flex-direction:column; gap:2px; padding:20px 14px 16px; background:var(--bg-2); border-right:1px solid var(--line); overflow-y:auto; z-index:70; }
  .sb-brand{ display:flex; align-items:center; gap:.55ch; white-space:nowrap; text-decoration:none; color:var(--ink); font-family:Georgia,serif; font-weight:600; font-size:1.06rem; padding:2px 10px 4px; }
  .sb-brand small{ color:var(--ink-faint); font-family:ui-monospace,Menlo,monospace; font-weight:400; font-size:.6rem; letter-spacing:.12em; text-transform:uppercase; }
  .sb-label{ font-family:ui-monospace,Menlo,monospace; font-size:.6rem; letter-spacing:.18em; text-transform:uppercase; color:var(--ink-faint); padding:16px 12px 6px; }
  .sb-nav{ display:flex; flex-direction:column; }
  .sb-part{ display:flex; align-items:baseline; gap:.7ch; flex-wrap:wrap; padding:17px 12px 7px; }
  .sb-part:first-child{ padding-top:20px; }
  .sb-part .sb-part-n{ font-family:ui-monospace,Menlo,monospace; font-size:.6rem; letter-spacing:.16em; text-transform:uppercase; color:var(--hot-ink); font-weight:600; }
  .sb-part .sb-part-sub{ font-size:.72rem; color:var(--ink-faint); }
  .sb-list{ display:flex; flex-direction:column; gap:2px; }
  .sb-item{ display:flex; gap:10px; align-items:flex-start; padding:9px 11px; border-radius:10px; text-decoration:none; color:var(--ink-soft); font-size:.9rem; line-height:1.28; }
  .sb-item:hover{ background:var(--bg); color:var(--ink); }
  .sb-item[aria-current="page"]{ background:color-mix(in srgb, var(--hot-ink) 12%, var(--bg-2)); color:var(--ink); box-shadow:inset 0 0 0 1px color-mix(in srgb, var(--hot-ink) 35%, transparent); font-weight:500; }
  .sb-item .sb-n{ font-family:ui-monospace,Menlo,monospace; font-size:.72rem; color:var(--hot-ink); font-weight:600; min-width:2ch; padding-top:1px; }
  .sb-back{ padding:14px 11px 4px; }
  .sb-back a{ font-family:ui-monospace,Menlo,monospace; font-size:.72rem; color:var(--ink-faint); text-decoration:none; }
  .sb-back a:hover{ color:var(--hot-ink); }
  .sb-tools{ margin-top:auto; padding:12px 8px 2px; display:flex; }
  @media (min-width:900px){
    .topnav{ display:none; }
    .sidebar{ display:flex; }
    body{ padding-left:300px; }
  }
  /* editorial list (alternative to cards for item lists) */
  .deflist{ margin-top:1.6em; background:transparent; border:none; border-radius:0; box-shadow:none; padding:0; }
  .deflist .drow{ display:grid; grid-template-columns:minmax(140px,215px) 1fr; gap:6px 34px; padding:1.3em 0; border-bottom:1px solid var(--line); align-items:start; }
  .deflist .drow:last-child{ border-bottom:none; }
  .deflist .dtag{ display:block; font-family:ui-monospace,Menlo,monospace; font-size:.66rem; letter-spacing:.14em; text-transform:uppercase; color:var(--hot-ink); font-weight:600; margin-bottom:.45em; }
  .deflist .dterm{ font-family:Georgia,"Iowan Old Style","Times New Roman",serif; font-size:1.18rem; font-weight:600; color:var(--ink); line-height:1.2; }
  .deflist .ddesc{ margin:0; color:var(--ink-soft); font-size:.97em; }
  @media (max-width:640px){ .deflist{ padding:0; } .deflist .drow{ grid-template-columns:1fr; gap:4px; padding:1.15em 0; } }
  /* ---------- Quiz / check your understanding ---------- */
  /* editorial: no card box, hairline rows, big serif numeral, chevron toggle */
  .quiz{ margin-top:1.6em; display:flex; flex-direction:column; gap:0; counter-reset:q; max-width:820px; }
  .q{ background:transparent; border:0; border-bottom:1px solid var(--line); border-radius:0; box-shadow:none; }
  .q:last-child{ border-bottom:0; }
  .q > summary{ list-style:none; cursor:pointer; padding:1.4em 0; display:flex; align-items:baseline; gap:1.1ch; }
  .q > summary::-webkit-details-marker{ display:none; }
  .q > summary::before{ counter-increment:q; content:counter(q); flex:none; min-width:2.2rem; font-family:Georgia,"Iowan Old Style","Times New Roman",serif; font-size:1.7rem; font-weight:600; line-height:1; color:var(--hot-ink); }
  .q-t{ flex:1; font-family:Georgia,"Iowan Old Style","Times New Roman",serif; font-size:1.15rem; font-weight:600; color:var(--ink); line-height:1.35; }
  .q > summary:hover .q-t{ color:var(--hot-ink); }
  .q > summary:focus-visible{ outline:3px solid var(--hot-ink); outline-offset:2px; border-radius:6px; }
  .q-hint{ flex:none; align-self:center; margin-left:.5ch; color:var(--ink-faint); }
  .q-hint::after{ content:"›"; font-size:1.5rem; line-height:1; display:inline-block; transition:transform .2s ease; }
  .q[open] .q-hint{ color:var(--hot-ink); }
  .q[open] .q-hint::after{ transform:rotate(90deg); }
  @media (prefers-reduced-motion: reduce){ .q-hint::after{ transition:none; } }
  .q-a{ margin:0 0 1.4em 2.7rem; padding:0; border-top:0; }
  .q-a p{ margin:0 0 .7em; color:var(--ink-soft); } .q-a p:last-child{ margin-bottom:0; }
  .q-a strong{ color:var(--ink); }
  @media (max-width:640px){ .q > summary{ padding:1.2em 0; gap:.9ch; } .q > summary::before{ font-size:1.45rem; min-width:1.9rem; } .q-t{ font-size:1.05rem; } .q-a{ margin-left:1.9rem; } }

  /* ---------- Language switcher ---------- */
  .langsel{ display:inline-flex; align-items:center; gap:2px; border:1px solid var(--line); background:var(--bg-2); border-radius:999px; padding:2px; box-shadow:var(--shadow); }
  .lang-opt{ font-family:ui-monospace,Menlo,monospace; font-size:.72rem; letter-spacing:.06em; text-decoration:none; color:var(--ink-faint); padding:.32em .72em; border-radius:999px; line-height:1; }
  .lang-opt:hover{ color:var(--ink); }
  .lang-opt[aria-current="true"]{ color:hsl(30 60% 12%); background:linear-gradient(hsl(36 92% 56%),hsl(30 88% 50%)); font-weight:600; }
  .lang-opt:focus-visible{ outline:3px solid var(--hot-ink); outline-offset:2px; }

  /* ---------- Feedback button (floating, bottom-right; opens the Google Form in a new tab) ---------- */
  /* same editorial pill language as .menu-btn / .langsel: white surface, hairline border, whisper
     shadow, pill radius; amber only on the small chat glyph, as the sparing accent */
  .feedback-fab{ position:fixed; right:clamp(16px,3.5vw,28px); bottom:clamp(16px,3.5vw,28px); z-index:65;
    display:inline-flex; align-items:center; gap:.6ch; padding:.62em 1.05em .62em .95em;
    background:var(--bg-2); color:var(--ink-soft); border:1px solid var(--line); border-radius:999px;
    box-shadow:var(--shadow); text-decoration:none; font-size:.86rem; font-weight:500; line-height:1;
    transition:transform .14s ease, color .16s ease, border-color .16s ease; }
  .feedback-fab:hover{ transform:translateY(-1px); color:var(--hot-ink); }
  .feedback-fab:active{ transform:translateY(0); }
  .feedback-fab:focus-visible{ outline:3px solid var(--hot-ink); outline-offset:2px; }
  .feedback-fab .fb-ic{ flex:none; width:16px; height:16px; color:var(--hot-ink); }
  .feedback-fab .fb-ic svg{ display:block; width:100%; height:100%; }
  @media (max-width:560px){ .feedback-fab{ padding:.55em .9em; font-size:.8rem; } }
  @media (prefers-reduced-motion: reduce){ .feedback-fab{ transition:none; } }