/* ============================================================
   Shapes Infinity — "Learn AI" lesson pages (/learn/:slug)
   Layout + skin on top of playground.css (light content canvas)
   ============================================================ */

.lesson { max-width: 860px; margin-inline: auto; padding-bottom: 40px; }

.lesson-head { padding: clamp(28px, 5vh, 56px) 0 10px; }
.lesson-head h1 { margin-top: 18px; font-size: clamp(2rem, 4.6vw, 3.4rem); max-width: 20ch; }
.lesson-hook { margin-top: 14px; font-size: 1.08rem; font-weight: 650; color: #c25400; max-width: 56ch; }

.lesson-section { margin-top: clamp(36px, 5vw, 56px); }
.lesson-section > h2, .lesson-card > h2 { font-size: clamp(1.35rem, 2.4vw, 1.9rem); margin-bottom: 16px; }
.lesson-lead { color: var(--muted); margin-bottom: 18px; max-width: 62ch; }

.lesson-card {
  border: 1px solid var(--line); border-radius: var(--radius);
  background: var(--glass); padding: clamp(18px, 3vw, 28px);
  margin-top: clamp(20px, 3vw, 30px);
}
.lesson-card p { color: var(--muted); line-height: 1.7; max-width: 70ch; }
.lesson-card p + p { margin-top: 10px; }
.lesson-card h3 { font-size: 1.05rem; margin-bottom: 10px; }

.lesson-defs { display: grid; grid-template-columns: 1fr 1fr; gap: var(--gap); margin-top: 10px; }
.lesson-card--kid { border-color: rgba(42, 209, 126, 0.5); background: rgba(42, 209, 126, 0.07); margin-top: 0; }
.lesson-card--adult { border-color: rgba(61, 139, 255, 0.45); background: rgba(61, 139, 255, 0.06); margin-top: 0; }
.lesson-oneline { margin-top: 12px; font-weight: 700; color: var(--ink) !important; }
.lesson-tech { margin-top: 12px; font-size: 0.88rem; }
.lesson-card--analogy { border-color: rgba(168, 102, 255, 0.45); background: rgba(168, 102, 255, 0.06); }
.lesson-breaks { margin-top: 12px; font-size: 0.88rem; font-style: italic; }

.lesson-examples { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--gap); }
.lesson-example { margin-top: 0; display: flex; flex-direction: column; }
.lesson-ex-tag {
  align-self: flex-start; font-size: 0.72rem; font-weight: 700;
  background: linear-gradient(135deg, #ff6b00, #ffb21e); color: #1a1005;
  border-radius: var(--pill); padding: 5px 13px; margin-bottom: 12px;
}
.lesson-example p { font-size: 0.9rem; }
.lesson-try { margin-top: auto !important; padding-top: 10px; font-weight: 650; color: #14804d !important; }

.lesson-steps { list-style: none; display: grid; gap: 14px; counter-reset: step; }
.lesson-steps li {
  display: flex; gap: 16px; align-items: flex-start;
  border: 1px solid var(--line); border-radius: var(--radius-sm);
  background: var(--glass); padding: 16px 20px;
}
.step-num {
  flex-shrink: 0; width: 38px; height: 38px; display: flex; align-items: center; justify-content: center;
  border-radius: 12px; background: #17131f; color: #fff;
  font-family: var(--font-display); font-weight: 700;
}
.lesson-steps p { color: var(--muted); font-size: 0.92rem; margin-top: 4px; max-width: 62ch; }

.lesson-card--notes { border-color: rgba(255, 178, 30, 0.55); background: rgba(255, 178, 30, 0.08); }
.lesson-notes { list-style: none; display: grid; gap: 8px; }
.lesson-notes li { padding-inline-start: 26px; position: relative; color: var(--ink); font-weight: 550; }
.lesson-notes li::before { content: "✓"; position: absolute; inset-inline-start: 0; color: #b97800; font-weight: 700; }

.lesson-tips { display: grid; grid-template-columns: 1fr 1fr; gap: var(--gap); }
.lesson-tips .lesson-card { margin-top: 0; }
.lesson-tips ul { padding-inline-start: 18px; color: var(--muted); display: grid; gap: 6px; }
.mistake, .correction { font-size: 0.92rem; }
.mistake span, .correction span {
  display: inline-block; font-size: 0.7rem; font-weight: 700; border-radius: var(--pill);
  padding: 2px 10px; margin-inline-end: 8px;
}
.mistake span { background: rgba(255, 85, 68, 0.15); color: #c03428; }
.correction span { background: rgba(42, 209, 126, 0.18); color: #14804d; }
.mistake + .correction { margin-top: 4px; }
.correction + .mistake { margin-top: 14px; }
.lesson-card--memory { border-color: rgba(0, 200, 255, 0.45); background: rgba(0, 200, 255, 0.06); }

.lesson-glossary { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.gloss {
  border: 1px solid var(--line); border-radius: var(--radius-sm);
  background: var(--glass); padding: 12px 16px;
}
.gloss dt { font-weight: 700; color: var(--ink); }
.gloss dt em { font-style: normal; font-weight: 600; font-size: 0.76rem; color: #c25400; margin-inline-start: 6px; }
.gloss dd { margin-top: 4px; font-size: 0.88rem; color: var(--muted); }

.quiz-card {
  border: 1px solid var(--line); border-radius: var(--radius);
  background: var(--glass); padding: clamp(16px, 3vw, 24px); margin-top: 16px;
}
.quiz-kind {
  display: inline-block; font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.12em;
  color: #7a3cf0; margin-bottom: 10px;
}
.quiz-q { font-family: var(--font-display); font-weight: 700; font-size: 1.05rem; max-width: 64ch; }
.quiz-hint, .quiz-model { margin-top: 10px; font-size: 0.9rem; color: var(--muted); }
.quiz-hint summary, .quiz-model summary { cursor: pointer; font-weight: 650; color: #c25400; }
.quiz-hint p, .quiz-model p { margin-top: 8px; }
.quiz-opts { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 14px; }
.quiz-opt {
  text-align: start; cursor: pointer; font: inherit; font-size: 0.92rem; font-weight: 550;
  border: 1px solid var(--line); border-radius: var(--radius-sm);
  background: var(--paper); color: var(--ink); padding: 12px 16px; min-height: 44px;
  transition: transform var(--dur-tap) var(--ease-fluid), border-color 0.2s, background 0.2s;
}
.quiz-opt:not(:disabled):hover { border-color: var(--orange); }
.quiz-opt:active { transform: scale(0.98); }
.quiz-opt.is-right { border-color: #14a45c; background: rgba(42, 209, 126, 0.14); }
.quiz-opt.is-wrong { border-color: #e04b3c; background: rgba(255, 85, 68, 0.12); }
.quiz-why { margin-top: 12px; font-size: 0.9rem; color: var(--muted); border-top: 1px dashed var(--line); padding-top: 10px; }

.lesson-card--recap { border-color: rgba(255, 107, 0, 0.5); background: rgba(255, 107, 0, 0.06); }
.lesson-card--recap ul { padding-inline-start: 18px; display: grid; gap: 6px; color: var(--ink); font-weight: 550; }
.lesson-friend { margin-top: 14px; font-weight: 650; color: #c25400 !important; }

.lesson-faq { border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--glass); padding: 14px 18px; margin-top: 10px; }
.lesson-faq summary { cursor: pointer; font-weight: 700; color: var(--ink); }
.lesson-faq p { margin-top: 8px; color: var(--muted); font-size: 0.92rem; }

.lesson-nav { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; margin-top: clamp(36px, 5vw, 56px); }
.lesson-nav .btn-hero { margin-inline-start: auto; }

/* waiting page */
.lesson-wait { max-width: 620px; margin: 12vh auto 0; text-align: center; padding-bottom: 80px; }
.lesson-wait h1 { margin-top: 16px; font-size: clamp(1.8rem, 4vw, 2.8rem); }
.lesson-wait p { margin-top: 16px; color: var(--muted); }
.wait-sub { font-size: 0.9rem; }
.wait-orb {
  width: 64px; height: 64px; margin: 26px auto 0; border-radius: 50%;
  background: linear-gradient(135deg, #ff6b00, #ffb21e);
  box-shadow: 0 0 40px rgba(255, 107, 0, 0.45);
  animation: orb-pulse 1.6s ease-in-out infinite;
}
@keyframes orb-pulse { 0%, 100% { transform: scale(1); } 50% { transform: scale(1.18); } }

@media (max-width: 899px) {
  .lesson-defs, .lesson-examples, .lesson-tips, .lesson-glossary, .quiz-opts { grid-template-columns: 1fr; }
}

/* ============================================================
   v2 — visual-first lesson: animated diagram, flow steps, chips
   ============================================================ */

/* animated concept diagram */
.viz {
  border: 1px solid var(--line); border-radius: var(--radius);
  background: var(--glass); padding: clamp(20px, 3.5vw, 34px);
  margin-top: 26px; text-align: center;
}
.viz-title { font-family: var(--font-display); font-weight: 700; font-size: 1.05rem; margin-bottom: 20px; }
.viz-flow { display: flex; align-items: center; justify-content: center; flex-wrap: wrap; gap: 10px; }
.viz-node {
  display: inline-flex; align-items: center;
  padding: 13px 20px; border-radius: 14px;
  font-family: var(--font-display); font-weight: 700; font-size: 0.95rem;
  border: 2px solid; white-space: nowrap;
}
/* nodes pop in one by one when the diagram scrolls into view, then rest */
html.motion-on .viz .viz-node { opacity: 0; }
html.motion-on .viz.in-view .viz-node {
  animation: viz-pop 0.55s var(--ease-fluid) calc(var(--i) * 0.14s + 0.15s) both;
}
@keyframes viz-pop { from { opacity: 0; transform: scale(0.82) translateY(12px); } to { opacity: 1; transform: none; } }
.viz-node--input   { color: #1d5fc2; border-color: #3d8bff; background: rgba(61, 139, 255, 0.1); }
.viz-node--process { color: #6a2fd8; border-color: #a866ff; background: rgba(168, 102, 255, 0.1); }
.viz-node--output  { color: #14804d; border-color: #2ad17e; background: rgba(42, 209, 126, 0.12); }
.viz-node--warning { color: #b25000; border-color: #ff8b2e; background: rgba(255, 139, 46, 0.12); }
.viz-arrow { width: 34px; height: 14px; flex-shrink: 0; color: var(--muted); }
html.motion-on .viz-dash { animation: viz-march 0.9s linear infinite; }
@keyframes viz-march { to { stroke-dashoffset: -12; } }
.viz-caption { margin-top: 18px; font-size: 0.92rem; color: var(--muted); }
.viz-legend { display: flex; justify-content: center; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.viz-key {
  font-size: 0.7rem; font-weight: 700; border-radius: var(--pill); padding: 4px 12px;
  border: 1.5px solid;
}
.viz-key--input   { color: #1d5fc2; border-color: #3d8bff; }
.viz-key--process { color: #6a2fd8; border-color: #a866ff; }
.viz-key--output  { color: #14804d; border-color: #2ad17e; }
.viz-key--warning { color: #b25000; border-color: #ff8b2e; }

/* animated step flow: cards light up in sequence, forever */
.flow-steps {
  list-style: none; display: grid;
  grid-template-columns: repeat(var(--n, 4), 1fr); gap: 12px;
}
.flow-steps li {
  position: relative;
  border: 1px solid var(--line); border-radius: var(--radius-sm);
  background: var(--glass); padding: 16px;
}
.flow-steps li {
  transition: transform var(--dur-ui) var(--ease-fluid), border-color var(--dur-ui) var(--ease-fluid), box-shadow var(--dur-ui) var(--ease-fluid);
}
.flow-steps li:hover {
  transform: translateY(-5px);
  border-color: #ff6b00;
  box-shadow: 0 12px 30px rgba(255, 107, 0, 0.18);
}
.flow-steps .step-num { width: 32px; height: 32px; border-radius: 10px; font-size: 0.9rem; display: flex; align-items: center; justify-content: center; background: #17131f; color: #fff; font-family: var(--font-display); font-weight: 700; }
.flow-steps h3 { margin-top: 10px; font-size: 0.98rem; }
.flow-steps p { margin-top: 6px; font-size: 0.86rem; color: var(--muted); line-height: 1.5; }

/* takeaway chips */
.key-chips { display: flex; flex-wrap: wrap; gap: 10px; }
.key-chip {
  border: 1.5px solid rgba(255, 178, 30, 0.65); border-radius: var(--pill);
  background: rgba(255, 178, 30, 0.1);
  padding: 10px 18px; font-weight: 650; font-size: 0.9rem; color: var(--ink);
}
.key-chip { transition: transform var(--dur-tap) var(--ease-fluid), box-shadow var(--dur-ui) var(--ease-fluid); }
.key-chip:hover { transform: translateY(-3px); box-shadow: 0 8px 20px rgba(255, 178, 30, 0.25); }

/* example cards get hue shape decorations */
.lesson-example { position: relative; overflow: hidden; }
.lesson-example::after {
  content: ""; position: absolute; width: 74px; height: 74px; border-radius: 50%;
  bottom: -26px; inset-inline-end: -22px; opacity: 0.16; pointer-events: none;
}
.lesson-example--phone::after { background: #3d8bff; }
.lesson-example--world::after { background: #2ad17e; border-radius: 20%; transform: rotate(18deg); }
.lesson-example--work::after { background: #a866ff; border-radius: 74px 74px 0 0; height: 40px; }

@media (max-width: 899px) {
  .flow-steps { grid-template-columns: 1fr 1fr; }
  .viz-flow { flex-direction: column; }
  .viz-arrow { transform: rotate(90deg); }
  .viz-node { white-space: normal; text-align: center; }
}
@media (max-width: 599px) { .flow-steps { grid-template-columns: 1fr; } }