/* S4b "What's inside" (assets/inside/inside.js renders it, copy-inside.js holds every word).
   Calm, airy components on the V3 tokens, in draft c's language: 16 px cards with a hairline, tabular figures,
   a quiet green stage behind each component. Gentle motion only, and none at all for prefers-reduced-motion.
   Works on the plain base too (?draft=now): every draft c token has a fallback. */

#s4b {
  --in-lab: var(--c-lab, 600 12px/1.2 var(--v3-font-body));
  --in-paper: #fff;
  --in-hl: color-mix(in oklch, var(--v3-l-200) 85%, oklch(.93 .12 120));
}
#s4b .v3-section__head { max-width: 760px; }

/* ---------- the grid ---------- */
.in-grid { display: grid; grid-template-columns: minmax(0, 1fr); gap: 14px; }
@media (min-width: 760px) {
  .in-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
  .in-cell--page, .in-cell--book { grid-column: 1 / -1; }
}
@media (min-width: 1100px) {
  .in-grid { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .in-cell--page { grid-column: 1 / span 3; grid-row: 1 / span 2; }
  .in-cell--q { grid-column: 4 / span 3; }
  .in-cell--card { grid-column: 4 / span 3; }
  .in-cell--mock, .in-cell--ready, .in-cell--book { grid-column: span 2; }
}

.in-cell {
  display: flex; flex-direction: column; gap: 18px; min-width: 0;
  padding: 22px 20px 20px; border-radius: 16px; background: var(--v3-card);
  box-shadow: inset 0 0 0 1px var(--v3-line-strong), var(--v3-shadow-soft);
}
@media (min-width: 900px) { .in-cell { padding: 28px 28px 26px; } }
.in-cell__head { display: grid; gap: 6px; }
.in-cell__title { margin: 0; font: 600 21px/1.2 var(--v3-font-display); letter-spacing: -.01em; color: var(--v3-l-900); }
.in-cell__text { margin: 0; font: 400 16px/1.5 var(--v3-font-body); color: var(--v3-soft); max-width: 46ch; }
.in-cell__facts {
  margin: auto 0 0; padding-top: 2px; font: var(--in-lab); letter-spacing: .1em; text-transform: uppercase;
  color: var(--v3-anchor); font-variant-numeric: tabular-nums;
}
.in-stage {
  display: grid; place-items: center; padding: 18px; border-radius: 12px;
  background: var(--v3-l-50); box-shadow: inset 0 0 0 1px var(--v3-line);
}
@media (min-width: 900px) { .in-stage { padding: 24px; } }
.in-cell--page .in-stage { flex: 1; padding-block: 24px 30px; }
@media (min-width: 900px) { .in-cell--page .in-stage { padding: 36px 36px 44px; } }

/* ---------- (a) the Summary 2.0 page: an A4 sheet on a sheet ---------- */
.in-page {
  width: 100%; max-width: 520px; display: grid; gap: 14px; padding: 22px 20px 16px; border-radius: 4px;
  background: var(--in-paper); color: var(--v3-ink);
  box-shadow: 0 1px 2px rgb(0 0 0 / .06), 0 18px 40px -22px rgb(var(--v3-anchor-rgb) / .35), 9px 9px 0 -1px #fff, 9px 9px 0 0 var(--v3-line-strong);
}
@media (min-width: 900px) { .in-page { padding: 34px 36px 20px; gap: 16px; } }
@media (min-width: 1100px) { .in-page { min-height: 560px; grid-template-rows: auto auto auto auto auto auto 1fr; } }
.in-page__run {
  display: flex; justify-content: space-between; gap: 12px; padding-bottom: 10px; box-shadow: inset 0 -1px 0 var(--v3-line);
  font: 500 12px/1.3 var(--v3-font-body); letter-spacing: .04em; color: var(--v3-faint); font-variant-numeric: tabular-nums;
}
.in-page__h { margin: 0; font: 600 clamp(18px, 2.2vw, 21px)/1.25 var(--v3-font-display); letter-spacing: -.01em; color: var(--v3-l-900); }
.in-page__p { margin: 0; font: 400 15px/1.7 var(--v3-font-body); color: var(--v3-ink); }
@media (min-width: 900px) { .in-page__p { font-size: 16px; } }
/* the highlighter: a soft marker band that sweeps in from the left */
.in-hl {
  color: inherit; padding: 1px 2px; margin: 0 -2px; border-radius: 3px; box-decoration-break: clone; -webkit-box-decoration-break: clone;
  background: linear-gradient(var(--in-hl), var(--in-hl)) 0 60% / 0% 78% no-repeat;
}
.in-hl.is-on { background-size: 100% 78%; }
@media (prefers-reduced-motion: no-preference) { .in-hl:not(.is-still) { transition: background-size .7s cubic-bezier(.3, .7, .2, 1); } }

.in-math {
  display: flex; align-items: center; justify-content: center; gap: 8px; padding: 6px 0;
  font: 400 17px/1.2 "Times New Roman", Georgia, serif; font-style: italic; color: var(--v3-l-900);
}
.in-math__eq { font-style: normal; }
.in-math__sum { display: inline-grid; justify-items: center; line-height: 1; }
.in-math__sum b { font: 400 30px/1 "Times New Roman", Georgia, serif; font-style: normal; }
.in-math__sum small { font-size: 11px; }
.in-math__frac { display: inline-grid; justify-items: center; }
.in-math__frac > span:first-child { padding: 0 6px 3px; border-bottom: 1px solid currentColor; }
.in-math__frac > span:last-child { padding-top: 3px; }
.in-math sub, .in-math sup { font-size: 11px; }

.in-page__rule, .in-page__exam { margin: 0; display: grid; gap: 4px; padding: 12px 14px; border-radius: 8px; font: 400 14.5px/1.5 var(--v3-font-body); }
.in-page__rule b, .in-page__exam b { font: var(--in-lab); font-size: 11px; letter-spacing: .12em; text-transform: uppercase; }
.in-page__rule { background: var(--v3-l-50); box-shadow: inset 3px 0 0 var(--v3-l-300); color: var(--v3-ink); }
.in-page__rule b { color: var(--v3-soft); }
.in-page__exam { background: var(--v3-l-100); box-shadow: inset 3px 0 0 var(--v3-anchor); color: var(--v3-l-900); }
.in-page__exam b { color: var(--v3-anchor); }
.in-page__foot {
  align-self: end; display: flex; justify-content: space-between; gap: 12px; padding-top: 10px; margin-top: 4px;
  box-shadow: inset 0 1px 0 var(--v3-line); font: 500 11.5px/1.3 var(--v3-font-body); color: var(--v3-faint); font-variant-numeric: tabular-nums;
}

/* ---------- (b) the exam-style question ---------- */
.in-q { width: 100%; display: grid; gap: 12px; }
.in-q__tag { margin: 0; font: var(--in-lab); font-size: 11px; letter-spacing: .12em; text-transform: uppercase; color: var(--v3-anchor); }
.in-q__stem { margin: 0; font: 500 15.5px/1.5 var(--v3-font-body); color: var(--v3-ink); }
.in-q__opts { display: grid; gap: 8px; }
@media (min-width: 560px) { .in-q__opts { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.in-q__opt {
  display: flex; align-items: center; gap: 10px; min-height: 46px; padding: 9px 12px; border: 0; border-radius: 10px; text-align: left;
  font: 500 14.5px/1.35 var(--v3-font-body); color: var(--v3-ink); background: #fff; cursor: pointer;
  box-shadow: inset 0 0 0 1px var(--v3-line-strong); font-variant-numeric: tabular-nums;
}
@media (prefers-reduced-motion: no-preference) { .in-q__opt { transition: box-shadow .25s ease, background-color .25s ease; } }
.in-q__opt:hover { box-shadow: inset 0 0 0 1px var(--v3-l-400); }
.in-q__opt:focus-visible { outline: 2px solid var(--v3-anchor-top); outline-offset: 1px; }
.in-q__key {
  flex: none; display: grid; place-items: center; width: 24px; height: 24px; border-radius: 6px;
  font: 600 12px/1 var(--v3-font-body); color: var(--v3-soft); background: var(--v3-l-50); box-shadow: inset 0 0 0 1px var(--v3-line);
}
.in-q.is-answered .in-q__opt.is-right { background: var(--v3-l-100); box-shadow: inset 0 0 0 1.5px var(--v3-anchor); color: var(--v3-l-900); }
.in-q.is-answered .in-q__opt.is-right .in-q__key { background: var(--v3-anchor); color: #fff; box-shadow: none; }
.in-q.is-answered .in-q__opt.is-wrong { background: oklch(.97 .015 40); box-shadow: inset 0 0 0 1px oklch(.75 .08 40); }
.in-q.is-answered .in-q__opt:not(.is-right):not(.is-wrong) { color: var(--v3-faint); }
.in-q__hint { margin: 0; font: 500 13px/1.3 var(--v3-font-body); color: var(--v3-faint); }
.in-q__why {
  display: grid; gap: 4px; padding: 12px 14px; border-radius: 10px; background: #fff; box-shadow: inset 0 0 0 1px var(--v3-line-strong);
  font: 400 14.5px/1.55 var(--v3-font-body); color: var(--v3-ink); font-variant-numeric: tabular-nums;
}
.in-q__why[hidden] { display: none; }
.in-q__why b { font: 600 14.5px/1.3 var(--v3-font-body); color: var(--v3-anchor); }
@media (prefers-reduced-motion: no-preference) {
  .in-q__why:not([hidden]) { animation: in-rise .5s cubic-bezier(.3, .7, .2, 1) both; }
  @keyframes in-rise { from { transform: translateY(6px); } to { transform: none; } }
}

/* ---------- (c) the flashcard ---------- */
.in-flash {
  width: 100%; max-width: 440px; padding: 0; border: 0; background: none; cursor: pointer; perspective: 1200px;
  font: inherit; color: inherit; text-align: center;
}
.in-flash:focus-visible { outline: 2px solid var(--v3-anchor-top); outline-offset: 4px; border-radius: 14px; }
.in-flash__inner { display: grid; transform-style: preserve-3d; }
@media (prefers-reduced-motion: no-preference) { .in-flash__inner { transition: transform .6s cubic-bezier(.3, .7, .2, 1); } }
.in-flash__face {
  grid-area: 1 / 1; display: grid; align-content: center; justify-items: center; gap: 10px; min-height: 170px; padding: 22px 22px 18px;
  border-radius: 14px; background: #fff; box-shadow: inset 0 0 0 1px var(--v3-line-strong), 0 14px 30px -20px rgb(var(--v3-anchor-rgb) / .45);
  backface-visibility: hidden; -webkit-backface-visibility: hidden;
}
.in-flash__face--back { transform: rotateY(180deg); background: var(--v3-l-900); color: #fff; box-shadow: 0 14px 30px -20px rgb(var(--v3-anchor-rgb) / .6); }
.in-flash.is-flipped .in-flash__inner { transform: rotateY(180deg); }
.in-flash__lab { font: var(--in-lab); font-size: 11px; letter-spacing: .12em; text-transform: uppercase; color: var(--v3-anchor); }
.in-flash__face--back .in-flash__lab { color: oklch(.86 .08 167); }
.in-flash__term { font: 600 clamp(20px, 2.4vw, 24px)/1.2 var(--v3-font-display); letter-spacing: -.01em; color: var(--v3-l-900); }
.in-flash__def { font: 400 15px/1.55 var(--v3-font-body); color: rgb(255 255 255 / .92); max-width: 36ch; }
.in-flash__hint { font: 500 12px/1.3 var(--v3-font-body); color: var(--v3-faint); }
.in-flash__face--back .in-flash__hint { color: rgb(255 255 255 / .6); }
/* without the 3D flip (reduced motion), the faces simply swap */
@media (prefers-reduced-motion: reduce) {
  .in-flash.is-flipped .in-flash__inner { transform: none; }
  .in-flash__face--back { transform: none; visibility: hidden; }
  .in-flash.is-flipped .in-flash__face--back { visibility: visible; }
  .in-flash.is-flipped .in-flash__face--front { visibility: hidden; }
}

/* ---------- (d) the timed mock exam ---------- */
.in-mock {
  width: 100%; display: grid; gap: 12px; padding: 16px; border-radius: 12px; background: #fff;
  box-shadow: inset 0 0 0 1px var(--v3-line-strong);
}
.in-mock__top { display: flex; justify-content: space-between; align-items: center; gap: 10px; font: 500 12.5px/1.3 var(--v3-font-body); color: var(--v3-soft); }
.in-mock__clock {
  flex: none; display: inline-flex; align-items: baseline; gap: 5px; padding: 5px 9px; border-radius: 8px;
  background: var(--c-band, var(--v3-l-900)); color: rgb(255 255 255 / .7); font: 500 11px/1 var(--v3-font-body);
}
.in-mock__clock b { font: 600 15px/1 var(--v3-font-body); color: #fff; font-variant-numeric: tabular-nums; letter-spacing: .02em; }
.in-mock__ticks { display: flex; gap: 2px; }
.in-mock__ticks i { flex: 1 1 0; min-width: 0; height: 6px; border-radius: 2px; background: var(--v3-l-100); }
.in-mock__ticks i.is-done { background: var(--v3-l-400); }
.in-mock__ticks i.is-cur { background: var(--v3-anchor); }
.in-mock__q { margin: 2px 0 0; font: 500 14px/1.3 var(--v3-font-body); color: var(--v3-soft); font-variant-numeric: tabular-nums; }
.in-mock__q b { font-weight: 700; color: var(--v3-l-900); }
.in-mock__lines { display: grid; gap: 7px; }
.in-mock__lines i, .in-mock__opt i { display: block; height: 8px; border-radius: 4px; background: var(--v3-l-100); }
.in-mock__opts { display: grid; gap: 6px; margin-top: 4px; }
.in-mock__opt { display: flex; align-items: center; gap: 10px; padding: 7px 10px; border-radius: 8px; box-shadow: inset 0 0 0 1px var(--v3-line); }
.in-mock__opt > span { font: 600 11px/1 var(--v3-font-body); color: var(--v3-faint); }

/* ---------- (e) readiness per topic ---------- */
.in-ready { width: 100%; display: grid; gap: 10px; }
.in-ready__ex { justify-self: end; margin: 0; font: var(--in-lab); font-size: 10.5px; letter-spacing: .12em; text-transform: uppercase; color: var(--v3-faint); }
.in-ready__list { display: grid; gap: 11px; margin: 0; padding: 0; list-style: none; }
.in-ready__row { display: grid; gap: 6px; }
.in-ready__name { display: flex; align-items: center; justify-content: space-between; gap: 8px; font: 500 13.5px/1.3 var(--v3-font-body); color: var(--v3-ink); }
.in-ready__next {
  flex: none; padding: 3px 7px; border-radius: 6px; background: var(--v3-anchor); color: #fff;
  font: 600 10.5px/1 var(--v3-font-body); letter-spacing: .08em; text-transform: uppercase;
}
.in-ready__track { display: block; height: 8px; border-radius: 4px; background: #fff; box-shadow: inset 0 0 0 1px var(--v3-line); overflow: hidden; }
.in-ready__track i {
  display: block; height: 100%; width: 100%; border-radius: inherit; transform-origin: left center; transform: scaleX(var(--lvl));
  background: linear-gradient(90deg, var(--v3-l-400), var(--v3-anchor));
}
.in-ready__row.is-next .in-ready__track i { background: var(--v3-l-300); }
.in-ready.is-empty .in-ready__track i { transform: scaleX(0); transition: none; }
@media (prefers-reduced-motion: no-preference) { .in-ready__track i { transition: transform 1.1s cubic-bezier(.3, .7, .2, 1); } }
.in-ready__row:nth-child(2) .in-ready__track i { transition-delay: .08s; }
.in-ready__row:nth-child(3) .in-ready__track i { transition-delay: .16s; }
.in-ready__row:nth-child(4) .in-ready__track i { transition-delay: .24s; }
.in-ready__row:nth-child(5) .in-ready__track i { transition-delay: .32s; }
.in-ready__row:nth-child(6) .in-ready__track i { transition-delay: .4s; }

/* ---------- (f) the course book PDF ---------- */
.in-book {
  width: 100%; display: grid; grid-template-columns: 108px minmax(0, 1fr); grid-template-areas: "doc toc" "uses uses";
  column-gap: 18px; row-gap: 16px; align-items: center;
}
@media (min-width: 760px) and (max-width: 1099px) {
  .in-book { grid-template-columns: 132px minmax(0, 1fr) auto; grid-template-areas: "doc toc uses"; column-gap: 28px; }
  .in-book__uses { flex-direction: column; }
}
.in-book__doc { grid-area: doc; position: relative; display: block; aspect-ratio: 1 / 1.414; margin: 0 8px 8px 0; }
.in-book__sheet, .in-book__cover { position: absolute; inset: 0; border-radius: 4px; background: #fff; box-shadow: inset 0 0 0 1px var(--v3-line-strong); }
.in-book__sheet:nth-child(1) { transform: translate(8px, 8px); }
.in-book__sheet:nth-child(2) { transform: translate(4px, 4px); }
.in-book__cover {
  display: flex; flex-direction: column; gap: 4px; padding: 30px 9px 9px; overflow: hidden;
  box-shadow: inset 0 0 0 1px var(--v3-line-strong), 0 12px 24px -16px rgb(var(--v3-anchor-rgb) / .5);
}
.in-book__band { position: absolute; left: 0; right: 0; top: 0; height: 20px; background: var(--c-band, var(--v3-anchor)); }
.in-book__cover b { font: 600 13px/1.15 var(--v3-font-display); color: var(--v3-l-900); }
.in-book__cover small { font: 500 7px/1.3 var(--v3-font-body); color: var(--v3-soft); }
.in-book__badge {
  position: absolute; right: 7px; bottom: 7px; padding: 3px 5px; border-radius: 4px; background: var(--v3-anchor); color: #fff;
  font: 700 8.5px/1 var(--v3-font-body); letter-spacing: .08em;
}
.in-book__toc { grid-area: toc; display: grid; gap: 7px; margin: 0; padding: 0; list-style: none; }
.in-book__toc li { display: grid; grid-template-columns: 52px minmax(0, 1fr); gap: 8px; align-items: baseline; font: 500 13px/1.3 var(--v3-font-body); color: var(--v3-ink); }
.in-book__wk { font: 600 10.5px/1.3 var(--v3-font-body); letter-spacing: .08em; text-transform: uppercase; color: var(--v3-anchor); font-variant-numeric: tabular-nums; }
.in-book__uses { grid-area: uses; display: flex; flex-wrap: wrap; gap: 6px; margin: 0; padding: 0; list-style: none; }
.in-book__uses li {
  padding: 6px 10px; border-radius: 999px; background: #fff; box-shadow: inset 0 0 0 1px var(--v3-line-strong);
  font: 500 12.5px/1 var(--v3-font-body); color: var(--v3-l-800);
}

/* wide screens: the book sits in a third of the row, so the cover gets smaller type */
@media (min-width: 1100px) {
  .in-book { grid-template-columns: 92px minmax(0, 1fr); column-gap: 16px; }
  .in-book__toc li { grid-template-columns: 46px minmax(0, 1fr); gap: 6px; }
  .in-book__cover { padding-top: 24px; }
  .in-book__band { height: 15px; }
  .in-book__cover b { font-size: 10px; }
  .in-cell--mock .in-stage, .in-cell--ready .in-stage, .in-cell--book .in-stage { flex: 1; }
  .in-book__cover small { font-size: 6px; }
}