/* Shared Start here lesson layout (v3.1). Loaded after concepts.css. */

body.lesson {
  --spark: #F5841F;
  --body: #d8d0c4;
  --muted: #b3a99c;
  --link: #ffc7a3;
  --ink: #1a0c06;
  --shade: #1a1714;
  --focus: #ffe8d8;
  --ok: #a8d18d;
  --no: #ffb08a;
  --t1: 0.875rem;
  --t2: 1.125rem;
  --t3: 1.3125rem;
  --t4: 1.625rem;
  --t5: clamp(2rem, 1.4rem + 2.6vw, 2.625rem);
  --lesson-gap: 48px;
  --bar: 0px;
  color: var(--body);
  font-size: var(--t2);
  line-height: 1.6;
}

body.lesson .wrap { max-width: 72rem; }

body.lesson main {
  max-width: 35rem;
  margin: 0 auto;
  padding: 8px 0 48px;
}

body.lesson .vh {
  position: absolute !important;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

body.lesson section.check { background: none; border: 0; padding: 0; }
body.lesson .result { background: none; border: 0; padding: 0; margin: 8px 0 0; }
body.lesson .result:empty { margin: 0; padding: 0; border: 0; }

body.lesson .crumb { font-size: var(--t1); color: var(--muted); margin: 0 0 4px; }
body.lesson .crumb a { color: var(--muted); display: inline-block; padding: 12px 0; }

body.lesson h1 {
  max-width: none;
  font-size: var(--t5);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--text);
  margin: 0 0 16px;
  font-weight: 650;
}

body.lesson .gain {
  font-size: var(--t3);
  line-height: 1.45;
  color: var(--text);
  margin: 0 0 8px;
}

body.lesson .meta { font-size: var(--t1); color: var(--muted); margin: 0 0 32px; }

body.lesson h2 {
  font-size: var(--t4);
  line-height: 1.25;
  color: var(--text);
  margin: var(--lesson-gap) 0 16px;
  font-weight: 650;
  letter-spacing: -0.01em;
  text-transform: none;
}

body.lesson h3 {
  font-size: var(--t3);
  line-height: 1.35;
  color: var(--text);
  margin: 24px 0 8px;
  font-weight: 650;
}

body.lesson p { margin: 0 0 16px; }
body.lesson ul,
body.lesson ol { margin: 0 0 16px; padding-left: 1.3em; }
body.lesson li { margin: 0 0 8px; }
body.lesson strong { color: var(--text); }
body.lesson main a { color: var(--link); }
body.lesson main a:hover { color: var(--text); }

body.lesson .idea {
  font-size: var(--t3);
  line-height: 1.45;
  color: var(--text);
  border-left: 3px solid var(--spark);
  padding: 0 0 0 16px;
  margin: 0 0 24px;
}

body.lesson .idea-more { margin: 0 0 8px; }

body.lesson details.reveal { margin: 0 0 16px; }
body.lesson details.reveal summary {
  cursor: pointer;
  display: inline-flex;
  flex-direction: column;
  align-items: flex-start;
  min-height: 44px;
  color: var(--link);
  font-weight: 600;
  text-decoration: none;
}
body.lesson details.reveal summary .sum-t {
  text-decoration: underline;
  text-underline-offset: 0.18em;
  color: var(--link);
  font-weight: 600;
  font-size: inherit;
}
body.lesson details.reveal[open] summary { margin-bottom: 8px; }
body.lesson details.reveal > div { border-left: 2px solid var(--line-2, #4a433b); padding-left: 16px; }

body.lesson details.more {
  margin: 0 0 16px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
body.lesson details.more > summary {
  cursor: pointer;
  list-style: none;
  display: flex;
  gap: 12px;
  align-items: flex-start;
  min-height: 48px;
  padding: 12px 0;
}
body.lesson details.more > summary::-webkit-details-marker { display: none; }
body.lesson details.more > summary::before {
  content: "+";
  flex: none;
  width: 1.2em;
  color: var(--spark);
  font-weight: 700;
  font-size: var(--t3);
  line-height: 1.3;
}
body.lesson details.more[open] > summary::before { content: "−"; }
body.lesson .sum-t { display: block; color: var(--text); font-weight: 650; font-size: var(--t2); }
body.lesson .sum-d { display: block; color: var(--muted); font-size: var(--t1); line-height: 1.5; }
body.lesson details.more > .body { padding: 0 0 8px; }

body.lesson figure { margin: 16px 0 24px; }
body.lesson figure svg { display: block; width: 100%; max-width: 34rem; height: auto; margin: 0 auto; }
body.lesson figcaption { font-size: var(--t1); color: var(--muted); text-align: center; margin-top: 8px; }

body.lesson table { width: 100%; border-collapse: collapse; margin: 8px 0 16px; font-size: var(--t2); }
body.lesson th,
body.lesson td { text-align: left; vertical-align: top; padding: 10px 12px 10px 0; border-bottom: 1px solid var(--line); }
body.lesson thead th { font-size: var(--t1); color: var(--muted); font-weight: 700; border-bottom-color: var(--line-2, #4a433b); }
body.lesson tbody th { color: var(--text); font-weight: 650; }

body.lesson .ba { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin: 0 0 8px; }
body.lesson .ba h3 { margin-top: 0; padding-top: 10px; border-top: 2px solid var(--line-2, #4a433b); }
body.lesson .ba .after h3 { border-top-color: var(--spark); }

body.lesson .tryit {
  background: var(--shade);
  border-left: 4px solid var(--spark);
  padding: 24px;
  margin: 32px 0;
}
body.lesson .tryit h2 { margin-top: 0; }

body.lesson .btn {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 16px;
  background: transparent;
  color: var(--text);
  border: 1px solid var(--line-2, #4a433b);
  font: inherit;
  font-size: var(--t1);
  font-weight: 700;
  cursor: pointer;
}
body.lesson .btn-primary,
body.lesson .btn[aria-pressed="true"] {
  background: var(--spark);
  color: var(--ink);
  border-color: var(--spark);
}

body.lesson .q { margin: 0 0 24px; border: 0; padding: 0; min-width: 0; }
body.lesson .q legend { padding: 0; color: var(--text); font-weight: 600; margin: 0 0 12px; }
body.lesson .q .step { display: block; color: var(--muted); font-size: var(--t1); font-weight: 600; margin: 0 0 4px; }
body.lesson .opts { list-style: none; padding: 0; margin: 0; }
body.lesson .opts li { margin: 0 0 8px; }
body.lesson .opt {
  display: flex;
  gap: 12px;
  width: 100%;
  text-align: left;
  min-height: 48px;
  padding: 10px 14px;
  background: transparent;
  color: var(--body);
  border: 1px solid var(--line-2, #4a433b);
  font: inherit;
  cursor: pointer;
  line-height: 1.45;
}
body.lesson .opt:hover { border-color: var(--muted); }
body.lesson .opt .k { font-weight: 700; color: var(--text); flex: none; }
body.lesson .opt[aria-disabled="true"] { cursor: default; }
body.lesson .opt.is-right { border-color: var(--ok); }
body.lesson .opt.is-wrong { border-color: var(--no); }
body.lesson .why { display: block; margin: 6px 0 0 14px; }
body.lesson .why b { font-weight: 700; }
body.lesson .why .r { color: var(--ok); }
body.lesson .why .w { color: var(--no); }
body.lesson .q .status {
  position: absolute !important;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}
body.lesson .check-progress { font-size: var(--t1); color: var(--muted); margin: 0 0 8px; font-weight: 600; }
body.lesson .check-nav { margin: 8px 0 0; }
html.js body.lesson .q.is-off { display: none; }
body.lesson .result { color: var(--text); }

body.lesson .pager {
  margin: var(--lesson-gap) 0 0;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: 8px;
}
body.lesson .next {
  display: inline-flex;
  align-items: center;
  align-self: flex-start;
  min-height: 48px;
  padding: 0 18px;
  background: var(--spark);
  color: var(--ink);
  font-weight: 700;
  text-decoration: none;
}
body.lesson .next:hover { color: var(--ink); background: #ff9a45; }
body.lesson .pager .small { font-size: var(--t1); display: inline-flex; align-items: center; min-height: 44px; }
body.lesson .sources { font-size: var(--t1); color: var(--muted); margin-top: 24px; }
body.lesson .sources ol { padding-left: 1.4em; margin: 0; }
body.lesson .sources li { margin: 0; padding: 5px 0; }
body.lesson .sources a { color: var(--muted); }
body.lesson .finish { color: var(--text); }

body.lesson .lessonbar { display: none; }

@media (max-width: 720px) {
  body.lesson .top { position: static; }
}

@media (max-width: 640px) {
  html:has(body.lesson) { --bar: 44px; }
  body.lesson { --lesson-gap: 32px; --bar: 44px; }
  body.lesson main { padding: 8px 0 32px; }
  body.lesson .meta { margin-bottom: 24px; }
  body.lesson .lessonbar {
    display: flex;
    position: sticky;
    top: 0;
    z-index: 20;
    height: var(--bar);
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin: 0 0 8px;
    width: 100%;
    box-sizing: border-box;
    padding: 0 16px;
    background: rgba(12, 11, 10, 0.97);
    border-bottom: 1px solid var(--line);
    font-size: var(--t1);
  }
  body.lesson .lessonbar .where { color: var(--muted); white-space: nowrap; }
  body.lesson .lessonbar a { display: inline-flex; align-items: center; min-height: 44px; color: var(--link); font-weight: 600; }
  body.lesson .lessonbar .track { position: absolute; left: 0; right: 0; bottom: -1px; height: 2px; background: transparent; }
  body.lesson .lessonbar .fill { display: block; height: 100%; width: 0; background: var(--spark); }
  body.lesson .ba { grid-template-columns: 1fr; gap: 4px; }
  body.lesson .tryit { padding: 16px; margin: 24px -16px; }
  body.lesson table.stack thead { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
  body.lesson table.stack tr { display: block; padding: 8px 0; border-bottom: 1px solid var(--line); }
  body.lesson table.stack th,
  body.lesson table.stack td { display: block; border: 0; padding: 2px 0; }
  body.lesson table.stack td[data-h]::before { content: attr(data-h) ": "; color: var(--muted); font-size: var(--t1); font-weight: 700; }
  body.lesson .pager { padding-top: 16px; }
}

@media (prefers-reduced-motion: no-preference) {
  body.lesson .opt { transition: border-color 0.15s; }
}

html { scroll-padding-top: calc(var(--bar, 0px) + 12px); }
body.lesson :focus-visible { outline: 2px solid var(--focus); outline-offset: 3px; }