.lesson-shell,
.lesson-shell .band,
.lesson-shell .card {
  min-width: 0;
}

.lesson-shell {
  overflow-wrap: break-word;
}

.lesson-shell h1,
.lesson-shell h2,
.lesson-shell p,
.lesson-shell li,
.lesson-shell a {
  max-width: 100%;
}

.lesson-shell .code {
  white-space: normal;
  overflow-wrap: anywhere;
  line-height: 1.65;
}

.lesson-shell .callout {
  overflow-wrap: break-word;
}

.lesson-track {
  position: relative;
  display: grid;
  gap: 14px;
  margin-top: 22px;
}

.lesson-track::before {
  content: "";
  position: absolute;
  top: 20px;
  bottom: 20px;
  left: 27px;
  width: 1px;
  background: linear-gradient(
    180deg,
    color-mix(in srgb, var(--accent) 58%, transparent),
    color-mix(in srgb, var(--ok) 24%, transparent)
  );
}

.lesson-step {
  position: relative;
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr);
  gap: 14px;
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: 3px;
  background: var(--panel);
}

.step-index {
  position: relative;
  z-index: 1;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border: 1px solid var(--accent-border);
  border-radius: 50%;
  background: var(--panel);
  color: var(--text);
  font: 800 14px var(--mono);
}

.step-body {
  display: grid;
  gap: 10px;
  min-width: 0;
}

.observe {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
  padding: 12px;
  border: 1px solid color-mix(in srgb, var(--ok) 22%, transparent);
  border-radius: 3px;
  background: color-mix(in srgb, var(--ok) 5.5%, transparent);
}

.observe span {
  min-width: 0;
  color: color-mix(in srgb, var(--text) 78%, transparent);
  font-size: 13px;
  line-height: 1.45;
}

.lesson-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
}

.lesson-actions .button {
  flex: 0 1 auto;
}

.explain {
  flex: 1 1 280px;
  min-width: 0;
  color: var(--faint);
  font-size: 13px;
}

.myth {
  margin: 0;
  padding: 8px 12px;
  border-left: 2px solid color-mix(in srgb, var(--warn) 55%, transparent);
  border-radius: 4px;
  background: color-mix(in srgb, var(--warn) 6%, transparent);
  color: color-mix(in srgb, var(--text) 82%, transparent);
  font-size: 13px;
  line-height: 1.5;
}

.myth strong {
  color: var(--warn);
}

.diagnosis-track {
  gap: 10px;
  margin-top: 16px;
}

.diagnosis-track::before {
  display: none;
}

.diagnosis-row {
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 12px;
  padding: 12px 14px;
  background: color-mix(in srgb, var(--accent) 4%, transparent);
}

.diagnosis-row .step-index {
  width: 26px;
  height: 26px;
  border-style: dashed;
  font-size: 12px;
}

.diagnosis-row .step-body {
  gap: 6px;
}

/* --- Loop block diagram (motion.css contract: tokens + reduced-motion come
       from .motion-scope; the dash-flow keyframe is the kit's own) ---------- */
.loop-figure {
  margin: 6px 0 2px;
}

.loop-figure svg {
  display: block;
  width: 100%;
  height: auto;
}

.ld-wire {
  fill: none;
  stroke: color-mix(in srgb, var(--text) 40%, transparent);
  stroke-width: 2;
}

.ld-warnwire {
  stroke: color-mix(in srgb, var(--warn) 60%, transparent);
}

.ld-arrowhead {
  fill: color-mix(in srgb, var(--text) 60%, transparent);
}

.ld-flow {
  fill: none;
  stroke: var(--accent);
  stroke-width: 4;
  stroke-linecap: round;
  stroke-dasharray: 8 22;
  opacity: 0.85;
  animation: motion-dash-flow calc(var(--motion-dur-slow) / var(--motion-speed)) linear infinite;
}

.ld-box {
  fill: var(--panel);
  stroke: var(--accent-border);
  stroke-width: 1.5;
}

.ld-tap {
  fill: color-mix(in srgb, var(--text) 70%, transparent);
}

.ld-name {
  fill: var(--text);
  font: 600 14px var(--font);
  text-anchor: middle;
}

.ld-sign {
  fill: color-mix(in srgb, var(--text) 85%, transparent);
  font: 700 14px var(--mono);
  text-anchor: middle;
}

.ld-label {
  fill: color-mix(in srgb, var(--text) 62%, transparent);
  font: 12px var(--font);
  text-anchor: middle;
}

.ld-warntext {
  fill: color-mix(in srgb, var(--warn) 85%, transparent);
}

/* --- Static teaching figures ------------------------------------------- */
.lesson-figure {
  display: grid;
  gap: 8px;
  margin: 0;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 3px;
  background: var(--panel-soft);
}

.lesson-figure svg {
  display: block;
  width: 100%;
  height: auto;
}

.an-axis {
  stroke: color-mix(in srgb, var(--text) 35%, transparent);
  stroke-width: 1.5;
}

.an-band {
  fill: color-mix(in srgb, var(--ok) 7%, transparent);
}

.an-target {
  stroke: var(--ok);
  stroke-width: 1.5;
  stroke-dasharray: 6 6;
  opacity: 0.8;
}

.an-curve {
  fill: none;
  stroke: var(--accent);
  stroke-width: 3;
  stroke-linecap: round;
}

.an-note {
  stroke: color-mix(in srgb, var(--warn) 75%, transparent);
  stroke-width: 1.5;
}

.an-dash {
  stroke: color-mix(in srgb, var(--text) 40%, transparent);
  stroke-dasharray: 4 5;
}

.an-label {
  fill: color-mix(in srgb, var(--text) 66%, transparent);
  font: 12px var(--font);
}

.an-green {
  fill: color-mix(in srgb, var(--ok) 85%, transparent);
}

.an-warn {
  fill: color-mix(in srgb, var(--warn) 90%, transparent);
}

/* --- Failure-signature gallery ------------------------------------------ */
.sig-gallery {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 10px;
  margin-top: 14px;
}

.sig {
  display: grid;
  gap: 6px;
  margin: 0;
  padding: 10px 10px 8px;
  border: 1px solid var(--border);
  border-radius: 3px;
  background: var(--panel-soft);
}

.sig svg {
  display: block;
  width: 100%;
  max-width: 220px;
  height: auto;
  margin: 0 auto;
}

.sig figcaption {
  color: color-mix(in srgb, var(--text) 72%, transparent);
  font-size: 12px;
  text-align: center;
}

.sig-target {
  stroke: color-mix(in srgb, var(--ok) 60%, transparent);
  stroke-width: 1.5;
  stroke-dasharray: 5 5;
}

.sig-curve {
  fill: none;
  stroke: var(--accent);
  stroke-width: 2.5;
  stroke-linecap: round;
}

.title-line {
  display: inline;
}

@media (max-width: 860px) {
  .observe {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 620px) {
  .lesson-shell h1 {
    font-size: clamp(32px, 10vw, 40px);
    line-height: 1.02;
  }

  .title-line {
    display: block;
  }

  .lesson-shell .button {
    width: fit-content;
    max-width: 100%;
    overflow-wrap: anywhere;
  }

  .lesson-track::before {
    left: 21px;
  }

  .lesson-step {
    grid-template-columns: 44px minmax(0, 1fr);
    gap: 10px;
    padding: 14px;
  }

  .step-index {
    width: 32px;
    height: 32px;
  }
}