/* Neuronal Data Analyzer Lab Course (course.neuroanalyzerlab.com): the
   lesson app's own styles. Not the website's design: an app shell (bar on
   top, part navigator, one card per part), plain CSS, no libraries.
   Fonts: IBM Plex from /assets/fonts/ (SIL Open Font License 1.1, OFL.txt).
   Icons below are drawn here (simple SVG paths, the glyph cut out of a
   rounded square), not taken from an icon set. */

:root {
  color-scheme: light;
  --bg: #eef1f6; --panel: #ffffff; --raised: #f7f8fb;
  --ink: #172033; --muted: #556079; --faint: #8791a5; --line: #dde2ec; --track: #e6eaf1;
  --teal: #0e7c86; --teal-soft: #e0f3f4;
  --good: #1f7a4a; --good-soft: #e3f4ea; --bad: #b42318; --bad-soft: #fdecea;
  --warn: #9a5a07; --warn-soft: #fdf1dc; --demo: #6d3fc0; --demo-soft: #f1ebfb;
  --code-bg: #eef1f6;
  --p1: #0e7c86; --p2: #2a62c9; --p3: #7a4bc4; --p4: #b84a17; --p5: #b02f66; --p6: #2b7a31; --p7: #4b4fc4;
  --on-pc: #ffffff;
  --shadow: 0 1px 2px rgba(23, 32, 51, .06), 0 10px 30px rgba(23, 32, 51, .08);
  --body: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --display: "IBM Plex Sans Condensed", "IBM Plex Sans", system-ui, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --bar-h: 58px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #0d121a; --panel: #161d29; --raised: #1b2331;
    --ink: #e7ebf3; --muted: #a3adc0; --faint: #7d889c; --line: #2a3446; --track: #2a3446;
    --teal: #5ac7d0; --teal-soft: #14313a;
    --good: #72d29a; --good-soft: #15301f; --bad: #f4a097; --bad-soft: #3b1e1c;
    --warn: #ebb662; --warn-soft: #33281a; --demo: #c3a4f0; --demo-soft: #2a2139;
    --code-bg: #212a3a;
    --p1: #5ac7d0; --p2: #82abf5; --p3: #b99bf2; --p4: #f2985f; --p5: #ef84ae; --p6: #7fcb85; --p7: #a3a6f5;
    --on-pc: #0d121a;
    --shadow: 0 1px 2px rgba(0, 0, 0, .35), 0 10px 30px rgba(0, 0, 0, .3);
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0d121a; --panel: #161d29; --raised: #1b2331;
  --ink: #e7ebf3; --muted: #a3adc0; --faint: #7d889c; --line: #2a3446; --track: #2a3446;
  --teal: #5ac7d0; --teal-soft: #14313a;
  --good: #72d29a; --good-soft: #15301f; --bad: #f4a097; --bad-soft: #3b1e1c;
  --warn: #ebb662; --warn-soft: #33281a; --demo: #c3a4f0; --demo-soft: #2a2139;
  --code-bg: #212a3a;
  --p1: #5ac7d0; --p2: #82abf5; --p3: #b99bf2; --p4: #f2985f; --p5: #ef84ae; --p6: #7fcb85; --p7: #a3a6f5;
  --on-pc: #0d121a;
  --shadow: 0 1px 2px rgba(0, 0, 0, .35), 0 10px 30px rgba(0, 0, 0, .3);
}

* { box-sizing: border-box; }
html { scroll-padding-top: calc(var(--bar-h) + 70px); -webkit-text-size-adjust: 100%; }
@media (min-width: 1000px) { html { scroll-padding-top: calc(var(--bar-h) + 20px); } }
body { margin: 0; background: var(--bg); color: var(--ink); font: 17px/1.6 var(--body); }
img { max-width: 100%; height: auto; }
a { color: var(--teal); text-underline-offset: 3px; }
code { font: 14.5px var(--mono); background: var(--code-bg); padding: 1px 6px; border-radius: 5px; overflow-wrap: anywhere; }
sup { line-height: 0; font-size: 11.5px; }
sup a { text-decoration: none; font-weight: 600; }
.muted { color: var(--muted); }
.skip { position: absolute; left: -999px; top: 8px; z-index: 20; background: var(--panel); padding: 8px 12px; border-radius: 8px; }
.skip:focus { left: 8px; }
:focus-visible { outline: 3px solid var(--teal); outline-offset: 2px; }

/* ---------------------------------------------------------------- app bar */
/* The bar spans the window; its contents line up with the page's column
   (--wrap: the width of .shell; 880px on pages with one column) */
body { --wrap: 1180px; }
body:has(.shell.solo) { --wrap: 880px; }
.appbar { position: sticky; top: 0; z-index: 10; height: var(--bar-h); display: flex; align-items: center; gap: 20px;
  padding-inline: max(24px, calc((100% - var(--wrap)) / 2 + 16px));
  background: color-mix(in srgb, var(--panel) 88%, transparent); backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px); border-bottom: 1px solid var(--line); }
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; flex: none; }
.brand span { display: grid; line-height: 1.15; }
.brand b { font: 600 17px var(--display); letter-spacing: .01em; }
.brand small { font-size: 11.5px; color: var(--muted); }
.appbar-title { margin: 0; flex: 1; min-width: 0; font-size: 14.5px; color: var(--muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.appbar-title { padding-left: 20px; border-left: 1px solid var(--line); line-height: 28px; }
.appbar-title a { color: var(--muted); text-decoration: none; }
.appbar-title a:hover { color: var(--ink); text-decoration: underline; text-underline-offset: 3px; }
.appbar-progress { display: flex; align-items: center; gap: 8px; font: 500 13px var(--mono); color: var(--muted); }
.appbar-progress .bar { width: 110px; height: 8px; border-radius: 99px; background: var(--track); overflow: hidden; }
.appbar-progress .bar i { display: block; height: 100%; width: 0; border-radius: 99px; background: linear-gradient(90deg, var(--p1), var(--p2), var(--p3)); transition: width .4s; }
.theme { flex: none; margin-left: auto; width: 38px; height: 38px; border-radius: 50%; border: 1px solid var(--line); background: var(--panel); color: var(--ink); cursor: pointer; display: grid; place-items: center; padding: 0; }
.theme svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.8; }
.theme svg .fill { fill: currentColor; stroke: none; }
@media (max-width: 640px) {
  .appbar { gap: 12px; padding-inline: 16px; }
  .brand small, .appbar-title { display: none; }
  .appbar-progress { margin-left: auto; }
  .appbar-progress .bar { width: 72px; }
}

/* ---------------------------------------------------- shell and navigator */
.shell { max-width: 1180px; margin: 0 auto; padding: 24px 16px 64px; display: grid; grid-template-columns: minmax(0, 1fr); gap: 24px; }
@media (min-width: 1000px) { .shell { grid-template-columns: 250px minmax(0, 1fr); gap: 32px; padding-top: 32px; } }
.lesson { min-width: 0; display: grid; gap: 28px; max-width: 840px; }

.partnav { position: sticky; top: var(--bar-h); z-index: 5; margin: -24px -16px 0; padding: 10px 16px;
  background: color-mix(in srgb, var(--bg) 92%, transparent); backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line); }
.partnav-head { display: none; }
.partnav ol { list-style: none; margin: 0; padding: 0; display: flex; gap: 6px; overflow-x: auto; scrollbar-width: none; }
.partnav ol::-webkit-scrollbar { display: none; }
.partnav a { display: flex; align-items: center; gap: 8px; text-decoration: none; color: var(--ink); white-space: nowrap;
  border: 1px solid var(--line); background: var(--panel); border-radius: 99px; padding: 4px 12px 4px 4px; font-size: 14px; }
.partnav .pn { flex: none; display: grid; place-items: center; width: 26px; height: 26px; border-radius: 50%;
  font: 600 13px var(--mono); color: var(--pc); background: color-mix(in srgb, var(--pc) 14%, var(--panel)); }
.partnav a[aria-current="true"] { border-color: var(--pc); box-shadow: 0 0 0 1px var(--pc) inset; }
.partnav li.done .pn { background: var(--pc); color: var(--on-pc); }
.partnav li.done .pn::after { content: "✓"; position: absolute; }
.partnav li.done .pn { position: relative; color: transparent; }
.partnav li.done .pn::after { color: var(--on-pc); }
@media (max-width: 999px) { .partnav .pt { display: none; } .partnav a[aria-current="true"] .pt { display: inline; } }
@media (min-width: 1000px) {
  .partnav { top: calc(var(--bar-h) + 32px); margin: 0; padding: 16px; align-self: start; background: var(--panel);
    border: 1px solid var(--line); border-radius: 18px; box-shadow: var(--shadow); backdrop-filter: none; }
  .partnav-head { display: grid; gap: 2px; margin: 0 0 12px; font-size: 13px; color: var(--muted); }
  .partnav-head b { color: var(--ink); font-size: 15px; }
  .partnav ol { flex-direction: column; gap: 4px; overflow: visible; }
  .partnav a { border: 0; border-radius: 12px; padding: 7px 10px 7px 7px; white-space: normal; font-size: 15px; background: none; }
  .partnav a:hover { background: var(--raised); }
  .partnav a[aria-current="true"] { background: color-mix(in srgb, var(--pc) 10%, var(--panel)); box-shadow: none; }
}

/* ------------------------------------------------------------------- hero */
.hero { position: relative; overflow: hidden; border-radius: 22px; padding: 30px 30px 26px; color: #fff;
  background: radial-gradient(120% 140% at 100% 0%, #2a62c9 0%, transparent 55%), linear-gradient(135deg, #10284a 0%, #0e5f6b 100%);
  box-shadow: var(--shadow); display: grid; gap: 14px; }
.hero > * { margin: 0; }
.hero a { color: #9fe6ec; }
.kicker { font: 500 13px var(--mono); letter-spacing: .08em; text-transform: uppercase; color: #a9d7f0; }
.hero h1 { font: 600 clamp(27px, 4.4vw, 40px)/1.15 var(--display); letter-spacing: -.005em; max-width: 24ch; }
.hero .lede { font-size: 18.5px; max-width: 58ch; color: #e3edf8; }
.facts { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; max-width: 560px; }
.facts li { background: rgba(255, 255, 255, .1); border: 1px solid rgba(255, 255, 255, .16); border-radius: 14px; padding: 10px 12px; display: grid; }
.facts b { font: 600 26px/1.1 var(--display); }
.facts span { font-size: 13px; color: #cfe0f2; }
.need { font-size: 15px; color: #d6e4f3; max-width: 62ch; }
.draft { font-size: 14px; background: rgba(255, 196, 92, .16); border: 1px solid rgba(255, 196, 92, .45); border-radius: 12px; padding: 8px 12px; color: #ffe9c2; }
.go { display: inline-flex; align-items: center; gap: 8px; background: #fff; color: #10284a !important; text-decoration: none;
  font-weight: 600; padding: 11px 20px; border-radius: 99px; }
.go::after { content: "→"; }
@media (max-width: 640px) {
  .hero { padding: 22px 18px 20px; border-radius: 18px; }
  .facts { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* ------------------------------------------------------------- part cards */
.part { background: var(--panel); border-radius: 22px; box-shadow: var(--shadow); overflow: hidden; border: 1px solid var(--line); }
.part-head { display: flex; align-items: center; gap: 16px; padding: 22px 28px; background: var(--pc); color: var(--on-pc);
  background-image: linear-gradient(120deg, rgba(255, 255, 255, .14), rgba(255, 255, 255, 0) 60%); }
.part-head > div { min-width: 0; }
.pnum { flex: none; display: grid; place-items: center; width: 54px; height: 54px; border-radius: 16px;
  background: var(--on-pc); color: var(--pc); font: 600 28px var(--display); }
.pmeta { margin: 0; font: 500 13px var(--mono); letter-spacing: .05em; text-transform: uppercase; opacity: .9; display: flex; flex-wrap: wrap; gap: 6px 10px; align-items: center; }
.chip { font: 600 11.5px var(--mono); letter-spacing: .05em; padding: 2px 8px; border-radius: 99px; border: 1px solid currentColor; }
.part-head h2 { margin: 2px 0 0; font: 600 clamp(23px, 3.2vw, 30px)/1.2 var(--display); }
.part-body { padding: 26px 28px 8px; display: grid; gap: 24px; }
.part-body > * { margin: 0; }
.part-body h3 { margin: 10px 0 -8px; font: 600 21px/1.3 var(--display); display: flex; align-items: center; gap: 10px; }
.part-body h3::before { content: ""; width: 5px; height: 22px; border-radius: 3px; background: var(--pc); flex: none; }
.say { font-size: 18px; line-height: 1.55; }
.part-foot { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px;
  margin: 18px 0 0; padding: 18px 28px 22px; border-top: 1px solid var(--line); background: var(--raised); }
.qsum { margin: 0; font-size: 15px; color: var(--muted); }
.qsum b { color: var(--ink); }
.done-btn { font: 600 16px var(--body); border: 0; border-radius: 99px; padding: 12px 22px; cursor: pointer; background: var(--pc); color: var(--on-pc); }
.done-btn:hover { filter: brightness(1.08); }
.done-btn.is-done::before { content: "✓ "; }
@media (max-width: 640px) {
  .part { border-radius: 18px; }
  .part-head { padding: 18px 16px; gap: 12px; }
  .pnum { width: 44px; height: 44px; font-size: 23px; border-radius: 13px; }
  .part-body { padding: 20px 16px 4px; gap: 20px; }
  .part-foot { padding: 16px; }
  .done-btn { width: 100%; }
}

/* ---------------------------------------------------- blocks with an icon */
.blk-tag { display: inline-flex; align-items: center; gap: 8px; margin: 0; font: 600 12.5px var(--mono); letter-spacing: .07em;
  text-transform: uppercase; color: var(--tagc, var(--teal)); }
.blk-tag::before { content: ""; width: 22px; height: 22px; flex: none; border-radius: 7px; background-color: var(--tagc, var(--teal));
  -webkit-mask: var(--icon) center / 22px 22px no-repeat; mask: var(--icon) center / 22px 22px no-repeat; }
.tryit { --tagc: var(--p2);
  --icon: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cmask id='m'%3E%3Crect width='24' height='24' rx='6' fill='white'/%3E%3Cg stroke-width='2' stroke-linecap='round'%3E%3Cpath d='M6 8h12M6 16h12' stroke='black'/%3E%3C/g%3E%3Ccircle cx='15' cy='8' r='2.8' fill='black'/%3E%3Ccircle cx='9' cy='16' r='2.8' fill='black'/%3E%3C/mask%3E%3Crect width='24' height='24' rx='6' mask='url(%23m)'/%3E%3C/svg%3E"); }
.doit { --tagc: var(--teal);
  --icon: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cmask id='m'%3E%3Crect width='24' height='24' rx='6' fill='white'/%3E%3Crect x='5' y='6' width='14' height='12' rx='2' fill='none' stroke='black' stroke-width='2'/%3E%3Cpath d='M5 10h14' stroke='black' stroke-width='2'/%3E%3C/mask%3E%3Crect width='24' height='24' rx='6' mask='url(%23m)'/%3E%3C/svg%3E"); }
.deeper { --tagc: var(--p3);
  --icon: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cmask id='m'%3E%3Crect width='24' height='24' rx='6' fill='white'/%3E%3Ccircle cx='11' cy='11' r='4.5' fill='none' stroke='black' stroke-width='2'/%3E%3Cpath d='M14.5 14.5 18 18' stroke='black' stroke-width='2.2' stroke-linecap='round'/%3E%3C/mask%3E%3Crect width='24' height='24' rx='6' mask='url(%23m)'/%3E%3C/svg%3E"); }
.fromlab { --tagc: var(--warn);
  --icon: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cmask id='m'%3E%3Crect width='24' height='24' rx='6' fill='white'/%3E%3Cpath d='M10 5h4M10.5 5v5L6.5 17.5a1 1 0 0 0 .9 1.5h9.2a1 1 0 0 0 .9-1.5L13.5 10V5' fill='none' stroke='black' stroke-width='1.8' stroke-linejoin='round'/%3E%3C/mask%3E%3Crect width='24' height='24' rx='6' mask='url(%23m)'/%3E%3C/svg%3E"); }
.numcheck { --tagc: var(--good);
  --icon: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cmask id='m'%3E%3Crect width='24' height='24' rx='6' fill='white'/%3E%3Cpath d='M6 12.5 10 16.5 18 8' fill='none' stroke='black' stroke-width='2.4' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/mask%3E%3Crect width='24' height='24' rx='6' mask='url(%23m)'/%3E%3C/svg%3E"); }

figure { margin: 0; display: grid; gap: 10px; }
figcaption { font-size: 15.5px; color: var(--muted); }
figure.fig { background: var(--raised); border: 1px solid var(--line); border-radius: 16px; padding: 18px; gap: 12px; }
figure.fig figcaption { color: var(--ink); max-width: 70ch; }
figure.tryit { background: color-mix(in srgb, var(--p2) 6%, var(--panel)); border: 2px solid color-mix(in srgb, var(--p2) 35%, var(--line)); }
figure.shot img { display: block; width: 100%; border-radius: 12px; border: 1px solid var(--line); box-shadow: var(--shadow); background: var(--panel); }
figure.shot figcaption { font-size: 14px; }

.doit { background: var(--teal-soft); border-radius: 16px; padding: 16px 18px; display: grid; gap: 10px; font-size: 16.5px; }
.doit p, .doit ol { margin: 0; }

details.deeper { border: 2px dashed color-mix(in srgb, var(--p3) 40%, var(--line)); border-radius: 16px; background: var(--panel); }
details.deeper > summary { list-style: none; cursor: pointer; padding: 14px 18px; display: flex; flex-wrap: wrap; align-items: center; gap: 6px 12px; }
details.deeper > summary::-webkit-details-marker { display: none; }
details.deeper > summary .sum { flex: 1 1 220px; font-weight: 600; }
details.deeper > summary::after { content: "+"; margin-left: auto; font: 600 22px/1 var(--mono); color: var(--p3); }
details.deeper[open] > summary::after { content: "–"; }
details.deeper > .prose { padding: 0 20px 16px; font-size: 16px; }
details.deeper > .prose > p { margin: 0 0 12px; }
details.deeper > .prose > p:last-child { margin-bottom: 0; }

.fromlab { background: var(--warn-soft); border-radius: 16px; padding: 16px 18px; display: grid; gap: 8px; font-size: 16px; }
.fromlab p, .fromlab ul { margin: 0; }
.fromlab ul { padding-left: 20px; display: grid; gap: 4px; }

/* -------------------------------------------------------------- questions */
.quiz { border: 2px solid color-mix(in srgb, var(--pc) 45%, var(--line)); background: color-mix(in srgb, var(--pc) 5%, var(--panel));
  border-radius: 18px; padding: 20px; display: grid; gap: 14px; }
.quiz > p { margin: 0; }
.q-label { display: flex; align-items: center; gap: 10px; font: 600 13px var(--mono); letter-spacing: .07em; text-transform: uppercase; color: var(--pc); }
.q-icon { display: grid; place-items: center; width: 26px; height: 26px; border-radius: 50%; background: var(--pc); color: var(--on-pc); font: 700 15px var(--body); }
.q-text { font: 600 20px/1.4 var(--body); }
.opts { display: grid; gap: 10px; }
.opt { display: flex; align-items: center; gap: 14px; width: 100%; min-height: 58px; text-align: left; cursor: pointer;
  font: 500 16.5px/1.4 var(--body); color: var(--ink); background: var(--panel); border: 2px solid var(--line);
  border-radius: 14px; padding: 12px 16px; transition: border-color .15s, background .15s, transform .1s; }
.opt:hover:not(:disabled) { border-color: var(--pc); }
.opt:active:not(:disabled) { transform: scale(.995); }
.opt .key { flex: none; display: grid; place-items: center; width: 32px; height: 32px; border-radius: 50%;
  border: 2px solid var(--line); font: 600 14px var(--mono); color: var(--muted); background: var(--panel); }
.opt:disabled { cursor: default; }
.quiz.answered .opt:not(.right):not(.wrong) { opacity: .5; }
.opt.right { border-color: var(--good); background: var(--good-soft); }
.opt.right .key { background: var(--good); border-color: var(--good); color: var(--panel); font-size: 0; }
.opt.right .key::after { content: "✓"; font-size: 17px; }
.opt.wrong { border-color: var(--bad); background: var(--bad-soft); }
.opt.wrong .key { background: var(--bad); border-color: var(--bad); color: var(--panel); font-size: 0; }
.opt.wrong .key::after { content: "✗"; font-size: 17px; }
.why { border-radius: 14px; padding: 14px 16px; background: var(--panel); border-left: 5px solid var(--line); font-size: 16.5px; animation: pop .25s ease-out; }
.why p { margin: 0; }
.why .verdict { display: block; font: 600 18px var(--body); margin-bottom: 2px; }
.why.is-right { border-left-color: var(--good); } .why.is-right .verdict { color: var(--good); }
.why.is-wrong { border-left-color: var(--bad); } .why.is-wrong .verdict { color: var(--bad); }
.q-actions { display: flex; flex-wrap: wrap; gap: 10px; }
.q-actions:not(:has(button:not([hidden]))) { display: none; }
.retry, .reveal { font: 600 15px var(--body); border-radius: 99px; padding: 9px 18px; cursor: pointer; border: 2px solid var(--pc); }
.retry { background: var(--pc); color: var(--on-pc); }
.reveal { background: transparent; color: var(--pc); }
.q-status { font-size: 0; height: 0; overflow: hidden; }
@keyframes pop { from { opacity: 0; transform: translateY(-4px); } to { opacity: 1; transform: none; } }
@media (prefers-reduced-motion: reduce) { .why { animation: none; } .appbar-progress .bar i { transition: none; } }
@media (max-width: 640px) { .quiz { padding: 16px 14px; } .q-text { font-size: 18.5px; } .opt { font-size: 16px; padding: 12px; gap: 12px; } }

/* --------------------------------------------- steps, cards, pipeline, lists */
ol.steps { list-style: none; counter-reset: st; margin: 0; padding: 0; display: grid; gap: 10px; }
ol.steps > li { counter-increment: st; display: flex; gap: 12px; align-items: baseline; }
ol.steps > li::before { content: counter(st); flex: none; display: grid; place-items: center; width: 26px; height: 26px;
  border-radius: 50%; background: var(--teal); color: var(--panel); font: 600 13px var(--mono); transform: translateY(-1px); }
.cards4 { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 165px), 1fr)); }
.cards4 .mini { background: var(--raised); border: 1px solid var(--line); border-top: 4px solid var(--pc); border-radius: 14px; padding: 12px 14px; display: grid; gap: 4px; font-size: 15px; }
.cards4 .mini span { color: var(--muted); }
ol.pipe { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); counter-reset: pipe; }
ol.pipe li { counter-increment: pipe; }
ol.pipe a { display: grid; gap: 2px; height: 100%; text-decoration: none; color: var(--ink); background: var(--raised); border: 2px solid var(--line); border-radius: 14px; padding: 12px 14px; font-size: 15px; }
ol.pipe a:hover { border-color: var(--pc); }
ol.pipe a b::before { content: counter(pipe); display: inline-grid; place-items: center; width: 24px; height: 24px; margin-right: 8px; border-radius: 50%; background: var(--pc); color: var(--on-pc); font: 600 12.5px var(--mono); }
ol.pipe a span { color: var(--muted); }
ol.pipe a i { font: 500 11.5px var(--mono); letter-spacing: .04em; text-transform: uppercase; color: var(--faint); font-style: normal; }
.checklist { display: grid; gap: 10px; background: var(--raised); border: 1px solid var(--line); border-radius: 16px; padding: 16px 18px; font-size: 16px; }
.checklist label { display: flex; gap: 12px; align-items: baseline; cursor: pointer; }
.checklist input { accent-color: var(--pc); width: 18px; height: 18px; transform: translateY(3px); flex: none; }
.checklist-score { margin: 0; min-height: 1.4em; font-weight: 600; color: var(--pc) !important; }

/* ------------------------------------------------------------ number check */
.numcheck { border: 2px solid color-mix(in srgb, var(--good) 40%, var(--line)); background: color-mix(in srgb, var(--good) 5%, var(--panel)); border-radius: 18px; padding: 20px; display: grid; gap: 14px; }
.numcheck form { display: grid; gap: 14px; }
.numcheck .actions { margin: 0; }
.tablewrap { overflow-x: auto; }
table.stack { width: 100%; border-collapse: collapse; font-size: 15.5px; }
table.stack th { text-align: left; font: 600 12px var(--mono); letter-spacing: .05em; text-transform: uppercase; color: var(--muted); padding: 6px 8px; border-bottom: 1px solid var(--line); }
table.stack td { padding: 8px; border-bottom: 1px solid var(--line); vertical-align: middle; }
table.stack input { width: 100%; max-width: 180px; font: 500 18px var(--mono); padding: 10px 12px; border: 2px solid var(--line); border-radius: 12px; background: var(--panel); color: var(--ink); }
table.stack input:focus { border-color: var(--good); outline: none; }
.check-result .score { font-size: 18px; margin: 0 0 8px; }
.pill { display: inline-block; font: 600 12px var(--mono); letter-spacing: .04em; text-transform: uppercase; padding: 3px 9px; border-radius: 99px; }
.pill.ok { background: var(--good-soft); color: var(--good); } .pill.warn { background: var(--warn-soft); color: var(--warn); } .pill.bad { background: var(--bad-soft); color: var(--bad); }
@media (max-width: 640px) {
  table.stack thead { display: none; }
  table.stack tr { display: grid; grid-template-columns: 1fr auto; gap: 4px 10px; padding: 10px 0; border-bottom: 1px solid var(--line); }
  table.stack td { border: 0; padding: 0; }
  table.stack td:nth-child(n+3) { grid-column: 1 / -1; }
  .numcheck { padding: 16px 14px; }
}

/* ----------------------------------------------------- buttons and the end */
.btn { display: inline-flex; align-items: center; gap: 8px; font: 600 15.5px var(--body); text-decoration: none; cursor: pointer;
  border-radius: 99px; padding: 10px 20px; border: 2px solid var(--line); background: var(--panel); color: var(--ink); }
.btn:hover { border-color: var(--teal); }
.btn.primary { background: var(--teal); border-color: var(--teal); color: var(--panel); }
.btn:disabled { opacity: .6; cursor: default; }
.actions { display: flex; flex-wrap: wrap; gap: 10px; }
.endcard { background: var(--panel); border: 1px solid var(--line); border-radius: 22px; padding: 26px 28px; box-shadow: var(--shadow); display: grid; gap: 14px; }
.endcard > * { margin: 0; }
.endcard h2 { font: 600 26px var(--display); }
ol.refs { padding-left: 26px; display: grid; gap: 8px; font-size: 14.5px; color: var(--muted); }
ol.refs li { overflow-wrap: anywhere; }
ol.refs li:target { background: var(--warn-soft); border-radius: 6px; }
.lesson-feedback { display: grid; gap: 16px; }
.lesson-feedback fieldset { border: 0; padding: 0; margin: 0; display: grid; gap: 10px; }
.lesson-feedback legend { font-weight: 600; padding: 0; margin-bottom: 10px; }
.checks { display: flex; flex-wrap: wrap; gap: 10px; }
.check { position: relative; }
.check input { position: absolute; opacity: 0; }
.check { display: inline-flex; align-items: center; border: 2px solid var(--line); border-radius: 99px; padding: 8px 20px; cursor: pointer; font-weight: 500; background: var(--panel); }
.check:has(input:checked) { border-color: var(--teal); background: var(--teal-soft); }
.check:has(input:focus-visible) { outline: 3px solid var(--teal); outline-offset: 2px; }
.lesson-feedback label:not(.check) { display: grid; gap: 8px; font-weight: 600; }
.lesson-feedback textarea { font: 400 16px var(--body); padding: 12px; border: 2px solid var(--line); border-radius: 14px; background: var(--panel); color: var(--ink); width: 100%; }
.form-status { margin: 0; min-height: 1.4em; }
.form-status.good { color: var(--good); } .form-status.bad { color: var(--bad); }
@media (max-width: 640px) { .endcard { padding: 20px 16px; border-radius: 18px; } }

/* -------------------------------------------- welcome page (index.html) */
.lessons { display: grid; gap: 16px; }
.lesson-card { display: grid; grid-template-columns: auto 1fr; gap: 6px 18px; align-items: center; text-decoration: none; color: var(--ink);
  background: var(--panel); border: 1px solid var(--line); border-radius: 22px; padding: 22px; box-shadow: var(--shadow); }
a.lesson-card:hover { border-color: var(--pc); }
.lesson-card .pnum { grid-row: span 3; background: var(--pc); color: var(--on-pc); }
.lesson-card h3 { margin: 0; font: 600 22px/1.25 var(--display); }
.lesson-card p { margin: 0; }
.lesson-card .meta { font: 500 12.5px var(--mono); letter-spacing: .05em; text-transform: uppercase; color: var(--pc); }
.lesson-card.soon { opacity: .75; box-shadow: none; }
.lesson-card .state { font-size: 14.5px; color: var(--muted); }
@media (max-width: 640px) { .lesson-card { grid-template-columns: 1fr; padding: 18px; } .lesson-card .pnum { grid-row: auto; } }

/* Lesson figures: schematics (inline SVG, docs/art/ldf_lesson_figures.py) and
   interactive plots (app/lesson-viz.js). Series colours:
   s1 blue, s2 orange (dashed), s0 muted grey; validated in both themes. */
.lesson { --s1: #2a78d6; --s2: #eb6834; --s0: var(--faint); --rbc: #c8433a; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .lesson { --s1: #3987e5; --s2: #d95926; --rbc: #e0685e; } }
:root[data-theme="dark"] .lesson { --s1: #3987e5; --s2: #d95926; --rbc: #e0685e; }
svg.schem.defs { position: absolute; width: 0; height: 0; overflow: hidden; }
.schem, .vizplot { display: block; width: 100%; height: auto; color: var(--ink); overflow: visible; }
.schem { max-width: 640px; margin: 0 auto; }
.schem text { font: 15px var(--body); fill: currentColor; }
.schem text.sm { font-size: 13.5px; }
.schem text.b { font-weight: 600; }
.schem text.mut { fill: var(--muted); }
.schem text.bad { fill: var(--bad); }
.schem .ln { stroke: currentColor; stroke-width: 1.6; fill: none; stroke-linecap: round; }
.schem .ln.thin { stroke-width: 1; }
.schem .ln.acc { stroke: var(--teal); stroke-width: 2; }
.schem .ln.dashl { stroke: var(--muted); stroke-dasharray: 5 4; stroke-width: 1.2; }
.schem .fsoft { fill: var(--teal-soft); }
.schem .mk { fill: currentColor; } .schem .mka { fill: var(--teal); }
.schem .hair { stroke: var(--line); stroke-width: 1; }
.schem .box { fill: var(--panel); stroke: var(--line); }
.schem .tis { fill: var(--track); }
.schem .still { fill: var(--faint); }
.schem .vessel, .vizplot .vessel { fill: var(--bad-soft); stroke: var(--rbc); stroke-width: 1; }
.schem .rbc, .vizplot .rbc { fill: var(--rbc); }
.schem .rbc.ring { fill: none; stroke: var(--s2); stroke-width: 2; }
.schem .c1 { fill: none; stroke: var(--s1); stroke-width: 2.2; stroke-linejoin: round; }
.schem .c2 { fill: none; stroke: var(--s2); stroke-width: 2.2; stroke-linejoin: round; stroke-dasharray: 7 4; }
.schem .ph1 { fill: none; stroke: var(--s1); stroke-width: 2; }
.schem .ph2 { fill: none; stroke: var(--s2); stroke-width: 2; stroke-dasharray: 6 3; }
.schem .stimbar, .vizplot .stim { fill: var(--warn-soft); }
.schem .stimfill { fill: var(--warn); }
.schem .win { fill: var(--teal-soft); stroke: var(--teal); }
.schem .win.bad { fill: var(--bad-soft); stroke: var(--bad); stroke-dasharray: 4 3; }
.schem .trial { fill: var(--faint); opacity: .7; }
.schem .animal { fill: var(--s1); } .schem .animal2 { fill: var(--s2); }
.schem .c1.ink { stroke: var(--s0); }
.schem .c1.thin2 { stroke-width: 1.4; opacity: .6; }

.viz { position: relative; display: grid; gap: 10px; }
.vizplot .grid line { stroke: var(--line); stroke-width: 1; }
.vizplot .tick { font: 12px var(--mono); fill: var(--faint); }
.vizplot .axis { font: 13px var(--body); fill: var(--muted); }
.vizplot .note { font: 12.5px var(--body); fill: var(--muted); }
.vizplot .line { fill: none; stroke-width: 2; stroke-linejoin: round; }
.vizplot .line.s1 { stroke: var(--s1); } .vizplot .line.s2 { stroke: var(--s2); } .vizplot .line.s0 { stroke: var(--s0); }
.vizplot .line.dash { stroke-dasharray: 6 4; }
.vizplot .line.thin { stroke-width: 1; opacity: .55; }
.vizplot .band.s1 { fill: var(--s1); opacity: .16; stroke: none; }
.vizplot .dot.s1 { fill: var(--s1); stroke: var(--panel); stroke-width: 1.5; }
.vizplot .dot.s2 { fill: var(--s2); stroke: var(--panel); stroke-width: 1.5; }
.vizplot .vline { stroke: var(--faint); stroke-dasharray: 3 3; }
.vizplot .cross { stroke: var(--muted); stroke-width: 1; }
.vizplot .speed { stroke: var(--ink); stroke-width: 2; }
.vizplot .pbar { fill: var(--teal); }
.viz-tip { position: absolute; left: 0; z-index: 2; pointer-events: none; background: var(--panel); border: 1px solid var(--line); border-radius: 8px; box-shadow: var(--shadow); padding: 6px 10px; font-size: 13px; line-height: 1.5; white-space: nowrap; }
.viz-controls { display: flex; flex-wrap: wrap; gap: 10px 22px; align-items: end; font-size: 14.5px; }
.viz-slider { display: grid; gap: 4px; flex: 1 1 240px; }
.viz-slider input { width: 100%; accent-color: var(--teal); }
.viz-toggles { display: flex; flex-wrap: wrap; gap: 6px 16px; }
.viz-toggles label { display: inline-flex; gap: 6px; align-items: center; }
.viz-legend { display: flex; flex-wrap: wrap; gap: 4px 18px; margin: 0; font-size: 13.5px; color: var(--muted); }
.key { display: inline-block; width: 20px; height: 0; border-top: 2px solid var(--s0); vertical-align: middle; margin-right: 6px; }
.key.s1 { border-color: var(--s1); } .key.s2 { border-color: var(--s2); } .key.dash { border-top-style: dashed; }
.key.stimk { height: 10px; border: 0; background: var(--warn-soft); outline: 1px solid var(--warn); }
.viz-readout { margin: 0; font-size: 14.5px; min-height: 2.6em; }
.vizplot.narrow { max-width: 600px; }
.lesson .sc { overflow-x: auto; -webkit-overflow-scrolling: touch; }
@media (max-width: 600px) {
  .lesson .sc .schem { min-width: 540px; }
  .lesson .sc { mask-image: linear-gradient(to right, #000 88%, transparent); -webkit-mask-image: linear-gradient(to right, #000 88%, transparent); }
  .lesson .sc.end { mask-image: none; -webkit-mask-image: none; }
}
.vizplot.narrow .note, .vizplot.narrow .axis { font-size: 19px; }
.shell.solo { grid-template-columns: minmax(0, 1fr); max-width: 880px; }
.shell.solo .lesson { max-width: none; }
/* Grid children may shrink below their content (wide tables scroll inside) */
.part-body > *, .numcheck > *, .numcheck form > *, .endcard > *, .lesson > * { min-width: 0; }