/* Quaternions, Visually: lesson text + interactive labs (on top of site.css) */
.qdoc { max-width: 1120px; }
.qdoc article > p, .qdoc article > ul, .qdoc article > ol { max-width: 760px; }
.qdoc article > p { margin: 0 0 16px; }
.qdoc h2 { font: 700 24px/1.25 'Sora', sans-serif; letter-spacing: -.015em; margin: 44px 0 10px; }
.qdoc h2 .hn { font: 600 14px 'Fira Code', monospace; color: var(--amber); margin-right: 10px; vertical-align: 3px; }
.qdoc li { margin: 6px 0; }
.qdoc .katex { font-size: 1.08em; }
.eq { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 14px 20px; margin: 18px 0 20px; max-width: 760px; overflow-x: auto; }
.eq .katex-display { margin: 6px 0; }
.eq-note { color: var(--muted); font-size: 15px; margin: -4px 0 0; }
.why { max-width: 760px; border-left: 4px solid var(--amber); background: color-mix(in srgb, var(--amber) 7%, transparent); border-radius: 0 12px 12px 0; padding: 12px 18px; margin: 18px 0 22px; font-size: 17px; }
.why b.wh { font: 700 12px 'Sora', sans-serif; letter-spacing: .1em; text-transform: uppercase; color: var(--amber); display: block; margin-bottom: 2px; }
.why p { margin: 4px 0; }
.key { max-width: 760px; background: var(--accent-soft); border-radius: 12px; padding: 14px 20px; margin: 22px 0; }
.key b.wh { font: 700 12px 'Sora', sans-serif; letter-spacing: .1em; text-transform: uppercase; color: var(--amber); display: block; margin-bottom: 4px; }
.key ul { margin: 4px 0 0; padding-left: 20px; }

/* lab */
.lab { margin: 22px 0 30px; background: var(--panel); border: 1px solid var(--line); border-radius: 16px; overflow: hidden; }
.lab-on { display: grid; grid-template-columns: minmax(0, 1.25fr) minmax(300px, 1fr); }
.lab-on.lab-wide { grid-template-columns: minmax(0, 1fr) minmax(300px, 400px); }
.lab-stage { display: grid; gap: 1px; background: var(--line); min-width: 0; }
.lab-wide .lab-stage { grid-template-columns: 1fr; }
.lab-stage .cv { position: relative; background: var(--bg); min-height: 380px; }
.lab-stage .cv.cv-plot { min-height: 210px; }
.lab-stage canvas { position: absolute; inset: 0; width: 100%; height: 100%; touch-action: none; cursor: grab; display: block; }
.lab-stage canvas.grab { cursor: grabbing; }
.cv-plot canvas { cursor: default; }
.cv-t { position: absolute; left: 12px; top: 10px; font: 600 12.5px 'Fira Code', monospace; color: var(--muted); pointer-events: none; }
.cv-h { position: absolute; right: 12px; bottom: 8px; font: 12px 'Source Sans 3', sans-serif; color: var(--dim); pointer-events: none; }
.lab-side { padding: 16px 18px; display: flex; flex-direction: column; gap: 12px; min-width: 0; border-left: 1px solid var(--line); }
.lab > figcaption { grid-column: 1 / -1; padding: 12px 18px; border-top: 1px solid var(--line); font-size: 15.5px; color: var(--muted); background: var(--panel-2); }
.lab > figcaption b { color: var(--text); }
.lab-stage + .lab-side + figcaption { }
.ctl { display: grid; grid-template-columns: 1fr auto; gap: 2px 10px; align-items: center; }
.ctl-n { font: 600 13.5px 'Source Sans 3', sans-serif; color: var(--text); }
.ctl-v { font: 500 13px 'Fira Code', monospace; color: var(--muted); text-align: right; }
.ctl input[type=range] { grid-column: 1 / -1; width: 100%; accent-color: var(--c, var(--amber)); margin: 2px 0; }
.lrow { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.lrow.pick { gap: 10px; }
.lbtn { border: 1px solid var(--line); background: var(--bg); color: var(--text); border-radius: 999px; padding: 6px 14px; font: 600 13.5px 'Source Sans 3', sans-serif; cursor: pointer; }
.lbtn:hover { border-color: var(--amber); color: var(--amber); }
.lbtn.pri { background: var(--amber); border-color: var(--amber); color: var(--on-accent); }
.lbtn.pri:hover { filter: brightness(1.08); color: var(--on-accent); }
.lbtn.cx { border-color: color-mix(in srgb, var(--amber) 60%, transparent); }
.lbtn.cy { border-color: color-mix(in srgb, var(--green) 60%, transparent); }
.lbtn.cz { border-color: color-mix(in srgb, var(--blue) 60%, transparent); }
.lchk { font: 600 13.5px 'Source Sans 3', sans-serif; display: inline-flex; align-items: center; gap: 4px; cursor: pointer; }
.lchk input { accent-color: var(--amber); }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 999px; overflow: hidden; flex-wrap: wrap; }
.seg button { border: 0; background: transparent; color: var(--muted); padding: 5px 12px; font: 600 13px 'Fira Code', monospace; cursor: pointer; }
.seg button + button { border-left: 1px solid var(--line); }
.seg button.on { background: var(--text); color: var(--bg); }
.rd { font: 13px/1.55 'Fira Code', monospace; color: var(--muted); background: var(--bg); border: 1px solid var(--line); border-radius: 10px; padding: 10px 12px; overflow-wrap: anywhere; }
.rd .rd-big { font-size: 14.5px; color: var(--text); font-weight: 500; margin: 3px 0; }
.rd .rd-k b { color: var(--text); }
.rd .warn { color: var(--amber); }
.rd-alert { margin-top: 8px; font: 600 14px/1.45 'Source Sans 3', sans-serif; color: var(--amber); background: color-mix(in srgb, var(--amber) 10%, transparent); border-radius: 8px; padding: 8px 10px; }
.rd-alert.ok { color: var(--green); background: color-mix(in srgb, var(--green) 10%, transparent); }
.lnote { margin: 0; font-size: 14px; color: var(--muted); }
.mx { border-collapse: collapse; margin: 4px 0 6px; font: 13px 'Fira Code', monospace; }
.mx td { padding: 2px 8px; text-align: right; border-left: 1px solid var(--line); }
.mx td:first-child { border-left: 2px solid var(--muted); } .mx td:last-child { border-right: 2px solid var(--muted); }
.bars { display: grid; gap: 6px; }
.bar { display: grid; grid-template-columns: 18px 1fr 64px; gap: 10px; align-items: center; font: 600 15px 'Fira Code', monospace; }
.bar code { background: none; border: 0; text-align: right; color: var(--text); }
.bt { position: relative; height: 14px; border-radius: 7px; background: var(--panel-2); overflow: hidden; }
.bt::after { content: ''; position: absolute; left: 50%; top: 0; bottom: 0; width: 1px; background: var(--dim); }
.bf { position: absolute; top: 0; bottom: 0; border-radius: 7px; }
.hero-lab { margin-top: 40px; }
.hero-lab.lab-on { grid-template-columns: minmax(0, 1fr) 340px; }
.hero-lab .lab-stage .cv { min-height: 440px; }

/* multiplication table */
.qtab-wrap { display: flex; gap: 28px; flex-wrap: wrap; align-items: center; margin: 18px 0 24px; }
.qtab { border-collapse: separate; border-spacing: 4px; font: 600 18px 'Fira Code', monospace; }
.qtab th { color: var(--muted); font-weight: 500; padding: 6px 12px; }
.qtab td { background: var(--panel); border: 1px solid var(--line); border-radius: 8px; padding: 10px 16px; text-align: center; cursor: pointer; min-width: 56px; }
.qtab td:hover { border-color: var(--amber); }
.qtab td.on { background: var(--accent-soft); border-color: var(--amber); }
.qtab td.neg { color: var(--amber); }
.qtab-out { min-height: 48px; max-width: 320px; color: var(--muted); font-size: 16px; }
.cycle { width: 190px; height: 170px; }

/* check yourself */
details.quiz { max-width: 760px; background: var(--panel); border: 1px solid var(--line); border-radius: 12px; margin: 10px 0; }
details.quiz > summary { list-style: none; cursor: pointer; padding: 12px 18px; font: 600 16px 'Source Sans 3', sans-serif; display: flex; gap: 10px; }
details.quiz > summary::-webkit-details-marker { display: none; }
details.quiz > summary::before { content: '?'; flex: none; display: inline-grid; place-items: center; width: 22px; height: 22px; border-radius: 50%; background: color-mix(in srgb, var(--amber) 15%, transparent); color: var(--amber); font: 700 13px 'Sora', sans-serif; }
details.quiz[open] > summary::before { content: '✓'; background: color-mix(in srgb, var(--green) 18%, transparent); color: var(--green); }
details.quiz > div { padding: 0 18px 14px 50px; color: var(--muted); }
details.quiz > div p { margin: 0 0 6px; }
.course-box { max-width: 760px; display: grid; grid-template-columns: auto 1fr; gap: 18px; align-items: center; background: var(--accent-soft); border-radius: 16px; padding: 18px 22px; margin: 34px 0 10px; }
.course-box svg { width: 54px; height: 54px; }
.course-box h3 { margin: 0 0 4px; font: 700 17px 'Sora', sans-serif; }
.course-box p { margin: 0; color: var(--muted); font-size: 15.5px; }
.course-box a.go { font-weight: 700; }
pre.c { margin: 12px 0 18px; max-width: 900px; }
.codehead { max-width: 900px; display: flex; justify-content: space-between; align-items: center; margin-top: 22px; font: 600 14px 'Fira Code', monospace; color: var(--green); }
.lmeta .ptag { font: 600 12px 'Source Sans 3', sans-serif; padding: 2px 10px; border-radius: 4px; color: var(--amber); background: color-mix(in srgb, var(--amber) 13%, transparent); }
.lmeta .ptag.Code { color: var(--blue); background: color-mix(in srgb, var(--blue) 13%, transparent); }
.home .anatomy { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.home .anatomy li b.n { font: 700 13px 'Fira Code', monospace; color: var(--amber); display: block; margin-bottom: 6px; }

@media (max-width: 900px) {
  .lab-on, .lab-on.lab-wide { grid-template-columns: 1fr; }
  .lab-side { border-left: 0; border-top: 1px solid var(--line); }
  .lab-stage .cv { min-height: 320px; }
  .home .anatomy { grid-template-columns: 1fr; }
}

.refs { max-width: 760px; padding-left: 20px; font-size: 16px; }
.refs li { margin: 8px 0; }
.refs span { color: var(--muted); font-size: 15px; }

details.quiz.more > summary::before { content: '+'; }
details.quiz.more[open] > summary::before { content: '−'; background: color-mix(in srgb, var(--amber) 15%, transparent); color: var(--amber); }
details.quiz.more > div { padding-left: 18px; color: var(--text); }
details.quiz.more .eq { background: var(--bg); }

.lab-head { grid-column: 1 / -1; padding: 9px 18px; border-bottom: 1px solid var(--line); background: var(--panel-2); font: 500 14.5px 'Source Sans 3', sans-serif; color: var(--text); }
.lab-head b { font: 700 11.5px 'Sora', sans-serif; letter-spacing: .1em; text-transform: uppercase; color: var(--amber); margin-right: 2px; }
.lab-stage .cv.cv-2d canvas { cursor: default; }
.lab-stage .cv.cv-2d.drag canvas { cursor: crosshair; }
.lab-stage .cv.cv-sq { min-height: 280px; }