.lesson-intro {
  max-width: 70ch;
}
.lesson-intro h1 {
  font-size: clamp(2rem, 5.5vw, 4rem);
  line-height: 1.1;
}
.lesson-actions,
.lesson-chapters,
[data-controls],
.lesson-nodes {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin: 1rem 0;
}
.lesson-chapters a {
  flex: 1 1 14rem;
  padding: 0.8rem;
  border: 1px solid var(--line);
  border-radius: 0.5rem;
}
.lesson-chapters [aria-current="step"] {
  border-color: var(--accent);
  text-decoration: underline;
}
.lesson-panel {
  padding: clamp(1rem, 3vw, 2rem);
  border: 1px solid var(--line);
  border-radius: 1rem;
  margin: 1.4rem 0;
  background: var(--surface);
}
.lesson-panel button,
.lesson-actions a,
.lesson-panel select,
.lesson-panel input,
.lesson-chapters a {
  min-height: 44px;
}
.lesson-panel button {
  padding: 0.65rem 0.85rem;
}
.lesson-status {
  font-size: 1.12rem;
  font-weight: 650;
  line-height: 1.5;
}
.lesson-evidence {
  line-height: 1.65;
  overflow-wrap: anywhere;
}
.lesson-bytes {
  font-family: monospace;
  line-height: 1.8;
  overflow-wrap: anywhere;
}
.lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 17rem), 1fr));
  gap: 1rem;
}
.lesson-grid label {
  display: grid;
  gap: 0.4rem;
}
.lesson-grid input:not([type="checkbox"]),
.lesson-grid select {
  width: 100%;
  min-width: 0;
  padding: 0.65rem;
  background: var(--bg);
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 0.4rem;
}
.lesson-scroll {
  overflow: auto;
  max-width: 100%;
}
.lesson-scroll table {
  width: 100%;
  border-collapse: collapse;
}
.lesson-scroll td,
.lesson-scroll th {
  padding: 0.65rem;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
.lesson-panel pre,
.power-article pre {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}
.power-article {
  max-width: 80ch;
  margin: 3rem auto;
  line-height: 1.75;
}
.power-article h2 {
  margin-top: 2.5rem;
  font-size: clamp(1.5rem, 3vw, 2rem);
}
.power-article h3 {
  margin-top: 1.7rem;
}
.power-article table {
  font-size: 0.95rem;
}
.power-article img {
  max-width: 100%;
}
.lesson-panel details {
  margin-top: 1rem;
}
.lesson-panel summary {
  cursor: pointer;
  padding: 1rem;
  min-height: 48px;
  list-style: none;
}
.lesson-panel summary::after {
  content: " +";
  float: right;
}
.lesson-panel details[open] > summary::after {
  content: " −";
}
.lesson-panel :focus-visible,
.lesson-chapters :focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 4px;
}
.lesson-panel [hidden] {
  display: none;
}
.lesson-panel h2 {
  font-size: clamp(1.45rem, 3vw, 2.25rem);
}
@media (max-width: 600px) {
  .lesson-panel {
    padding: 1rem;
  }
  .lesson-chapters a {
    flex-basis: 100%;
  }
  .lesson-status {
    font-size: 1rem;
  }
  .lesson-panel [data-controls] button {
    flex: 1 1 40%;
  }
}
@media (prefers-reduced-motion: reduce) {
  .lesson-panel * {
    animation: none !important;
    transition: none !important;
    scroll-behavior: auto !important;
  }
}

.lesson-panel select {
  max-width: 100%;
  width: 100%;
  padding: 0.65rem;
  background: var(--bg);
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 0.4rem;
}
.lesson-panel,
.power-article {
  min-width: 0;
}
.power-article a {
  overflow-wrap: anywhere;
}
.power-article {
  overflow-wrap: anywhere;
}
.power-article pre code {
  white-space: inherit;
  overflow-wrap: anywhere;
}
.power-article pre {
  max-width: 100%;
}

.power-state-path {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  list-style: none;
  padding: 0;
}
.power-state-path li {
  padding: 0.6rem;
  border: 1px solid var(--line);
  border-radius: 0.4rem;
  font-size: 0.85rem;
}
.power-state-path [aria-current="step"] {
  border-color: var(--accent);
  font-weight: 700;
  text-decoration: underline;
}
.power-state-path [aria-current="step"]::before {
  content: "Current: ";
}
.lesson-actions {
  align-items: center;
}
.lesson-actions a {
  display: inline-flex;
  align-items: center;
}
.lesson-actions .button {
  margin: 0;
}
.lesson-panel button {
  background: var(--bg);
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 0.5rem;
}
.lesson-panel [data-controls] button:nth-child(2),
.lesson-panel button.button {
  background: var(--accent);
  color: var(--button-ink);
  border-color: var(--accent);
}
.lesson-panel button:disabled {
  opacity: 0.45;
  cursor: default;
}

[data-inspected="true"] {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
  border-radius: 0.25rem;
}
.lesson-nodes .dma-story [aria-pressed="true"] {
  border-color: var(--accent);
  text-decoration: underline;
}
.lesson-bytes {
  display: block;
  line-height: 1.9;
}

/* Shared form rhythm across the power, PCIe and DMA lessons. */
.lesson-panel > h2 {
  margin-bottom: 1rem;
  line-height: 1.2;
}
.lesson-grid {
  align-items: end;
}
.lesson-grid > label {
  min-width: 0;
  align-self: stretch;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: 0.5rem;
}
.lesson-grid input:not([type="checkbox"]),
.lesson-grid select {
  min-height: 48px;
  font: inherit;
}
.lesson-grid label:has(input[type="checkbox"]) {
  justify-content: center;
  min-height: 48px;
  padding: 0.65rem;
  border: 1px solid var(--line);
  border-radius: 0.5rem;
  background: var(--bg);
}
.lesson-grid label > span:has(input[type="checkbox"]) {
  display: flex;
  align-items: flex-start;
  gap: 0.65rem;
}
.lesson-grid input[type="checkbox"] {
  width: 1.15rem;
  height: 1.15rem;
  min-height: 0;
  flex: 0 0 1.15rem;
  margin: 0.25rem 0 0;
}
.lesson-toggles {
  grid-column: 1/-1;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 16rem), 1fr));
  gap: 0.75rem;
  margin: 0;
}
.lesson-toggles legend {
  padding-block: 0.5rem;
  font-weight: 600;
}
.lesson-toggles label {
  display: flex;
  align-items: center;
}
.lesson-panel > form > label[for] {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 600;
}
.lesson-panel summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  width: 100%;
}
.lesson-panel summary::after {
  float: none;
  flex: none;
}
.lesson-actions > *,
[data-controls] > * {
  margin: 0;
}
.lesson-panel .lesson-actions {
  align-items: stretch;
}
.lesson-panel [data-controls] {
  align-items: center;
}
.lesson-panel input[type="range"] {
  min-width: 0;
  flex: 1 1 12rem;
  min-height: 44px;
}
.lesson-panel .lesson-scroll {
  border: 1px solid var(--line);
  border-radius: 0.6rem;
  margin-block: 1rem;
}
.lesson-panel .lesson-scroll th {
  background: var(--bg);
  font-weight: 650;
}
.lesson-panel .lesson-scroll th,
.lesson-panel .lesson-scroll td {
  line-height: 1.5;
}
.lesson-panel pre {
  font-size: 0.875rem;
  line-height: 1.6;
}
.power-article {
  margin-inline: 0;
}
.lesson-contrast {
  border-left: 3px solid var(--accent);
  padding: 0.75rem 1rem;
  margin-block: 1rem;
  background: var(--soft);
}
@media (max-width: 600px) {
  .lesson-grid {
    grid-template-columns: 1fr;
  }
  .lesson-actions > a,
  .lesson-actions > button {
    justify-content: center;
  }
}

#pcie-lesson-form {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}
@media (max-width: 600px) {
  #pcie-lesson-form {
    grid-template-columns: 1fr;
  }
}
.story-map {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  gap: 0.65rem;
  margin: 1rem 0;
}
.story-map div {
  flex: 1 1 11rem;
  display: grid;
  gap: 0.3rem;
  padding: 0.8rem;
  border: 1px solid var(--line);
  border-radius: 0.5rem;
}
.story-map > span {
  align-self: center;
  font-size: 1.5rem;
}
.lesson-three {
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: 0.3rem 1rem;
  line-height: 1.5;
}
.lesson-three dt {
  font-weight: 650;
}
.lesson-three dd {
  margin: 0;
}
.dma-story [aria-pressed="true"] {
  border-color: var(--accent);
}
@media (max-width: 600px) {
  .story-map > span {
    transform: rotate(90deg);
    width: 100%;
    text-align: center;
  }
  .lesson-three {
    grid-template-columns: 1fr;
  }
}