.lesson-hero { display: grid; grid-template-columns: minmax(0, 1fr) 290px; gap: 54px; align-items: center; }
.content-grid { display: grid; grid-template-columns: minmax(0, 1fr) 250px; gap: 62px; align-items: start; }
.article { min-width: 0; }
.article section { margin: 0 0 54px; scroll-margin-top: 90px; }
.article h3 { margin: 28px 0 10px; font-size: 1.32rem; }
.article p { margin: 0 0 18px; }
.article ul, .article ol { padding-left: 1.25rem; }
.article li { margin-bottom: 7px; }
.article strong { color: var(--indigo-dark); }

.decision-dial { position: relative; min-height: 344px; padding: 26px 24px; overflow: hidden; color: white; background: var(--indigo); border-radius: 28px; box-shadow: var(--shadow); }
.decision-dial::before { content: ""; position: absolute; right: -125px; bottom: -135px; width: 240px; height: 240px; border: 58px solid rgba(255,255,255,.07); border-radius: 50%; }
.dial-kicker { color: #c8d7ff; text-transform: uppercase; letter-spacing: .12em; font-size: .62rem; font-weight: 800; }
.dial-title { margin: 12px 0 25px; font-family: var(--display); font-size: 1.55rem; line-height: 1.13; }
.dial-line { position: relative; width: 5px; height: 192px; margin-left: 14px; background: linear-gradient(var(--mint), var(--saffron), #ed7b78); border-radius: 99px; }
.dial-point { position: absolute; left: 18px; width: 190px; color: #d5dcf6; font-size: .67rem; transform: translateY(-50%); }
.dial-point::before { content: ""; position: absolute; left: -23px; top: 50%; width: 10px; height: 10px; background: currentColor; border: 3px solid var(--indigo); border-radius: 50%; transform: translateY(-50%); }
.dial-point strong { display: block; color: white; font-size: .77rem; }
.dial-point.p1 { top: 0; }
.dial-point.p2 { top: 50%; }
.dial-point.p3 { top: 100%; }

.toc { position: sticky; top: 98px; }
.toc-title { margin-bottom: 12px; color: var(--muted); text-transform: uppercase; letter-spacing: .14em; font-size: .62rem; font-weight: 800; }
.toc a { display: block; padding: 7px 0 7px 13px; color: var(--muted); border-left: 1px solid var(--line); text-decoration: none; font-size: .74rem; line-height: 1.35; }
.toc a:hover { color: var(--indigo); border-color: var(--indigo); }
.toc-note { margin-top: 25px; padding: 14px; color: var(--indigo); background: #eef1ff; border-radius: 14px; font-size: .7rem; line-height: 1.45; }

.concept-card.ai { border-top: 4px solid var(--saffron); }
.concept-card.system { border-top: 4px solid var(--mint); }
.concept-card .mini { color: var(--indigo); font-family: var(--mono); font-size: .64rem; font-weight: 800; }
.flow { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin: 28px 0; padding-left: 0; list-style: none; }
.flow li, .flow span { margin: 0; padding: 9px 11px; background: white; border: 1px solid var(--line); border-radius: 10px; font-size: .72rem; font-weight: 700; }
.flow li:not(:last-child)::after { content: "→"; margin-left: 16px; color: var(--saffron); font-weight: 900; }
.decision-table th { color: var(--muted); text-transform: uppercase; letter-spacing: .1em; font-size: .66rem; }
.yes { color: #136c55; font-weight: 800; }
.no { color: #bb4c55; font-weight: 800; }
.callout.principle { background: #eef1ff; border: 1px solid #d9e0ff; border-left: 4px solid var(--indigo); }
.callout.warning { background: #fff5df; border: 1px solid #f3d89e; border-left: 4px solid var(--saffron); }
.callout .label { margin-bottom: 7px; color: var(--indigo); text-transform: uppercase; letter-spacing: .12em; font-size: .62rem; font-weight: 900; }

.loop-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 9px; margin: 26px 0; counter-reset: loop; }
.loop-step { position: relative; min-height: 105px; padding: 15px 14px 13px 43px; background: white; border: 1px solid var(--line); border-radius: 14px; }
.loop-step::before { counter-increment: loop; content: counter(loop); position: absolute; left: 13px; top: 14px; width: 21px; height: 21px; display: grid; place-items: center; color: white; background: var(--indigo); border-radius: 50%; font: 700 .65rem/1 var(--mono); }
.loop-step b { display: block; font-size: .76rem; line-height: 1.25; }
.loop-step span { display: block; margin-top: 5px; color: var(--muted); font-size: .67rem; line-height: 1.38; }
.choices { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; margin: 22px 0; }
.choice { padding: 13px; background: rgba(255,255,255,.055); border: 1px solid rgba(255,255,255,.18); border-radius: 13px; font-size: .78rem; }
.choice b { color: var(--saffron); }
.response-label { display: block; margin: 20px 0 7px; color: #b5c0e9; font-size: .7rem; font-weight: 700; }
.save-row { display: flex; align-items: center; gap: 12px; margin-top: 10px; }
.save-state { color: #aeb9dc; font-size: .68rem; }
.source-note { color: var(--muted); font-size: .75rem; }
.lesson-footer { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-top: 46px; padding-top: 24px; border-top: 1px solid var(--line); }
.next-button { padding: 10px 0; color: var(--indigo); background: transparent; border: 0; cursor: pointer; font-weight: 800; }

@media (max-width: 1020px) {
  .lesson-hero { grid-template-columns: 1fr; }
  .decision-dial { min-height: 270px; }
  .dial-line { height: 120px; }
  .content-grid { grid-template-columns: 1fr; }
  .toc { display: none; }
}
@media (max-width: 760px) {
  .lesson-hero { gap: 30px; margin-bottom: 45px; }
  .choices, .loop-grid { grid-template-columns: 1fr; }
  .decision-table { display: block; max-width: 100%; overflow-x: auto; }
}

/* OpensourceUI-inspired reading shell: neutral, flat, and content-led. */
.lesson-hero {
  grid-template-columns: minmax(0, 720px) 220px;
  gap: clamp(36px, 6vw, 72px);
  align-items: end;
}

.content-grid {
  grid-template-columns: minmax(0, 720px) 220px;
  gap: clamp(36px, 6vw, 72px);
}

.article section { margin-bottom: 64px; }
.article h3 { font-size: 1.42rem; }
.article p { margin-bottom: 20px; }
.article li { margin-bottom: 9px; }

.decision-dial {
  min-height: 320px;
  padding: 24px 22px;
  background: var(--ink);
  border: 1px solid var(--ink);
  border-radius: 12px;
  box-shadow: none;
}

.decision-dial::before { display: none; }
.dial-kicker { color: #bdbdb8; letter-spacing: .1em; }
.dial-line { width: 3px; background: var(--saffron); }
.dial-point { color: #d8d8d3; }
.dial-point::before { border-color: var(--ink); }

.toc {
  top: 94px;
  padding-left: 18px;
  border-left: 1px solid var(--line);
}

.toc-title { color: #8a8a85; letter-spacing: .1em; }

.toc a {
  padding: 7px 0 7px 12px;
  border-left-color: var(--line);
  font-size: .75rem;
}

.toc a:hover {
  color: var(--ink);
  border-color: var(--ink);
}

.toc-note {
  margin-top: 24px;
  padding: 13px;
  color: #4f4f4b;
  background: #f3f3f1;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.concept-card.ai,
.concept-card.system { border-top: 0; }

.concept-card .mini,
.callout .label { color: var(--saffron); letter-spacing: .1em; }

.flow li,
.flow span,
.loop-step {
  border-radius: 7px;
  box-shadow: none;
}

.callout.principle,
.callout.warning {
  background: #f4f4f2;
  border: 1px solid var(--line-strong);
}

.loop-grid { gap: 1px; overflow: hidden; background: var(--line); border: 1px solid var(--line); border-radius: 9px; }
.loop-step { border: 0; border-radius: 0; }
.choice { border-radius: 7px; }
.response-label { color: #c9c9c5; }
.save-state { color: #c9c9c5; }
.next-button { color: var(--ink); }

.lesson-aside {
  position: sticky;
  top: 94px;
  display: grid;
  gap: 0;
  padding-left: 18px;
  border-left: 1px solid var(--line);
}

.aside-card {
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.aside-card:first-child { padding-top: 0; }
.aside-card .mini { color: #8a8a85; font-size: .62rem; letter-spacing: .1em; }
.aside-card h3 { margin: 7px 0; font-size: 1.15rem; }
.aside-card p { margin: 0; color: var(--muted); font-size: .75rem; line-height: 1.55; }

@media (max-width: 1020px) {
  .lesson-hero,
  .content-grid { grid-template-columns: 1fr; }
  .lesson-aside { display: none; }
}