.lab-page-shell {
  --lab-ink: #172033;
  --lab-muted: #5d6677;
  --lab-line: #d9dee8;
  --lab-paper: #ffffff;
  --lab-wash: #f4f6f9;
  --lab-cobalt: #3157c8;
  --lab-cobalt-dark: #24449f;
  --lab-cobalt-soft: #e9efff;
  --lab-teal: #267c73;
  --lab-teal-soft: #e5f4f0;
  --lab-yellow: #f2c94c;
  --lab-yellow-soft: #fff8d9;
  --lab-red: #b8473c;
  max-width: 1180px;
  margin: 0 auto;
  padding: 1rem 0 4rem;
  color: var(--lab-ink);
}

.lab-page-header {
  max-width: 900px;
  margin-bottom: 1.5rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--lab-line);
}

.lab-page-kicker,
.lab-small-label,
.lab-step-label {
  margin: 0 0 0.45rem;
  color: var(--lab-cobalt);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.lab-page-title {
  max-width: 820px;
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 3.6rem);
  line-height: 1.03;
  letter-spacing: 0;
}

.lab-page-description {
  max-width: 760px;
  margin: 1rem 0;
  color: var(--lab-muted);
  font-size: 1.08rem;
}

.lab-page-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.25rem;
  color: var(--lab-muted);
  font-size: 0.8rem;
}

.lab-skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 1000;
  padding: 0.75rem 1rem;
  background: var(--lab-ink);
  color: #fff;
  transform: translateY(-150%);
}

.lab-skip-link:focus {
  color: #fff;
  transform: translateY(0);
}

.grill-lab *,
.grill-lab *::before,
.grill-lab *::after {
  box-sizing: border-box;
}

.grill-lab button,
.grill-lab textarea,
.grill-lab input {
  font: inherit;
}

.grill-lab button {
  min-height: 44px;
}

.grill-lab button:focus-visible,
.grill-lab textarea:focus-visible,
.grill-lab input:focus-visible,
.grill-lab summary:focus-visible,
.grill-lab a:focus-visible {
  outline: 3px solid var(--lab-yellow);
  outline-offset: 3px;
}

.lab-utility {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: center;
  min-height: 44px;
  padding: 0.4rem 0;
  border-top: 1px solid var(--lab-line);
  color: var(--lab-muted);
  font-size: 0.8rem;
}

.lab-save-status {
  margin: 0;
}

.js-only {
  display: none !important;
}

.lab-js button.js-only {
  display: inline-flex !important;
}

.lab-js .lab-stage-actions.js-only,
.lab-js .lab-export-actions.js-only {
  display: flex !important;
}

.lab-js .lab-question-nav.js-only {
  display: grid !important;
}

.lab-question-nav {
  position: sticky;
  top: 56px;
  z-index: 40;
  display: grid;
  grid-template-columns: 1.4fr repeat(6, 44px) 1.4fr;
  gap: 0.4rem;
  margin: 0 -0.5rem 1.5rem;
  padding: 0.65rem;
  background: rgba(250, 250, 249, 0.96);
  border-top: 1px solid var(--lab-line);
  border-bottom: 1px solid var(--lab-line);
  backdrop-filter: blur(12px);
}

.lab-question-nav button {
  border: 1px solid var(--lab-line);
  border-radius: 4px;
  background: var(--lab-paper);
  color: var(--lab-muted);
  cursor: pointer;
  font-size: 0.78rem;
  font-weight: 600;
}

.lab-question-nav button:hover {
  border-color: var(--lab-cobalt);
  color: var(--lab-cobalt);
}

.lab-question-nav button.is-active {
  border-color: var(--lab-cobalt);
  background: var(--lab-cobalt);
  color: #fff;
}

.lab-question-nav button.is-complete:not(.is-active) {
  border-color: var(--lab-teal);
  background: var(--lab-teal-soft);
  color: #155a53;
}

.lab-layout {
  display: grid;
  grid-template-columns: minmax(220px, 270px) minmax(0, 1fr);
  gap: clamp(2rem, 5vw, 4.5rem);
  align-items: start;
}

.lab-reference-sticky {
  position: sticky;
  top: 134px;
}

.lab-reference h2 {
  margin: 0 0 1rem;
  font-family: var(--font-display);
  font-size: 1.35rem;
}

.lab-evidence-rail {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none;
}

.lab-evidence-rail::before {
  position: absolute;
  top: 18px;
  bottom: 18px;
  left: 17px;
  width: 2px;
  background: var(--lab-line);
  content: "";
}

.lab-evidence-rail li {
  position: relative;
  display: grid;
  grid-template-columns: 36px 1fr;
  min-height: 68px;
  padding-bottom: 0.65rem;
  color: var(--lab-muted);
}

.lab-evidence-rail li > span {
  position: relative;
  z-index: 1;
  display: grid;
  width: 36px;
  height: 36px;
  place-items: center;
  border: 2px solid var(--lab-line);
  border-radius: 50%;
  background: var(--lab-paper);
  color: var(--lab-muted);
  font-family: var(--font-mono);
  font-size: 0.75rem;
}

.lab-evidence-rail strong,
.lab-evidence-rail small {
  grid-column: 2;
  padding-left: 0.8rem;
}

.lab-evidence-rail strong {
  align-self: end;
  color: var(--lab-ink);
  font-size: 0.9rem;
}

.lab-evidence-rail small {
  align-self: start;
  font-size: 0.72rem;
  line-height: 1.3;
}

.lab-evidence-rail li.is-current > span {
  border-color: var(--lab-cobalt);
  background: var(--lab-cobalt);
  color: #fff;
}

.lab-evidence-rail li.is-current strong {
  color: var(--lab-cobalt);
}

.lab-reference-note {
  margin-top: 0.65rem;
  padding-top: 0.85rem;
  border-top: 1px solid var(--lab-line);
  color: var(--lab-muted);
  font-size: 0.75rem;
  line-height: 1.5;
}

.lab-surface {
  min-width: 0;
  scroll-margin-top: 135px;
}

.lab-stage {
  animation: lab-enter 180ms ease-out;
}

.lab-js .lab-stage:not(.is-active) {
  display: none;
}

@keyframes lab-enter {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.lab-stage-heading {
  margin-bottom: 1.5rem;
  padding-bottom: 1.25rem;
  border-bottom: 2px solid var(--lab-ink);
}

.lab-stage-heading h2 {
  margin: 0 0 0.7rem;
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 3vw, 2.7rem);
  line-height: 1.08;
  letter-spacing: 0;
}

.lab-stage-heading p:last-child {
  max-width: 740px;
  margin: 0;
  color: var(--lab-muted);
  font-size: 1.03rem;
}

.lab-step-label {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}

.lab-step-label span {
  color: var(--lab-muted);
  letter-spacing: 0;
  text-transform: none;
}

.lab-cover-figure {
  display: grid;
  grid-template-columns: minmax(220px, 0.75fr) minmax(240px, 1fr);
  gap: 1.5rem;
  align-items: end;
  margin: 0 0 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--lab-line);
}

.lab-cover-figure img {
  width: 100%;
  margin: 0;
  border: 1px solid var(--lab-line);
  border-radius: 4px;
}

.lab-cover-figure figcaption {
  max-width: 430px;
  color: var(--lab-ink);
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 700;
  line-height: 1.35;
}

.lab-teaching-band,
.lab-worked-example {
  display: grid;
  grid-template-columns: minmax(180px, 0.65fr) minmax(0, 1.35fr);
  gap: 2rem;
  padding: 1.7rem 0;
  border-bottom: 1px solid var(--lab-line);
}

.lab-teaching-band h3,
.lab-worked-example h3 {
  margin: 0;
  font-size: 1.2rem;
  line-height: 1.25;
}

.lab-compare-lines p {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 1rem;
  margin: 0;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--lab-line);
}

.lab-compare-lines p:last-child {
  border-bottom: 0;
}

.lab-compare-lines span {
  color: var(--lab-muted);
  font-family: var(--font-mono);
  font-size: 0.78rem;
}

.lab-four-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  background: var(--lab-line);
  border: 1px solid var(--lab-line);
}

.lab-four-grid div {
  padding: 1rem;
  background: var(--lab-paper);
}

.lab-four-grid dt {
  color: var(--lab-cobalt);
  font-weight: 700;
}

.lab-four-grid dd {
  margin: 0.25rem 0 0;
  color: var(--lab-muted);
  font-size: 0.85rem;
  line-height: 1.45;
}

.lab-example-intro p:last-child {
  margin: 0.75rem 0 0;
  color: var(--lab-muted);
  font-size: 0.85rem;
}

.lab-worked-example ol {
  margin: 0;
  padding-left: 1.35rem;
}

.lab-worked-example li {
  margin-bottom: 0.55rem;
  padding-left: 0.35rem;
}

.lab-key-distinction {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 1.7rem 0;
  background: var(--lab-line);
  border: 1px solid var(--lab-line);
}

.lab-key-distinction div {
  padding: 1.1rem;
  background: var(--lab-yellow-soft);
}

.lab-key-distinction strong,
.lab-key-distinction span {
  display: block;
}

.lab-key-distinction span {
  margin-top: 0.2rem;
  color: var(--lab-muted);
  font-size: 0.84rem;
}

.lab-key-distinction > p {
  grid-column: 1 / -1;
  margin: 0;
  padding: 1rem 1.1rem;
  background: var(--lab-paper);
  color: var(--lab-muted);
  font-size: 0.86rem;
}

.lab-glossary,
.lab-hint {
  margin: 1rem 0;
  border-top: 1px solid var(--lab-line);
  border-bottom: 1px solid var(--lab-line);
}

.lab-glossary summary,
.lab-hint summary {
  min-height: 44px;
  padding: 0.7rem 0;
  color: var(--lab-cobalt);
  cursor: pointer;
  font-weight: 650;
}

.lab-glossary dl {
  margin: 0;
}

.lab-glossary dl div {
  display: grid;
  grid-template-columns: 150px 1fr;
  gap: 1rem;
  padding: 0.65rem 0;
  border-top: 1px solid var(--lab-line);
}

.lab-glossary dt {
  font-weight: 700;
}

.lab-glossary dd {
  margin: 0;
  color: var(--lab-muted);
}

.lab-hint p {
  margin: 0 0 0.9rem;
  color: var(--lab-muted);
}

.lab-privacy-note,
.lab-callout,
.lab-noscript {
  margin: 1.4rem 0;
  padding: 1rem 1.1rem;
  border-left: 4px solid var(--lab-teal);
  background: var(--lab-teal-soft);
}

.lab-privacy-note p,
.lab-callout {
  margin-bottom: 0;
}

.lab-required-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.6rem;
  margin: 1rem 0 1.25rem;
  padding: 0;
  list-style-position: inside;
}

.lab-required-list li {
  min-height: 48px;
  padding: 0.7rem 0.8rem;
  border-left: 3px solid var(--lab-cobalt);
  background: var(--lab-wash);
  font-weight: 600;
}

.lab-prompt-line {
  overflow-x: auto;
  margin: 1rem 0;
  padding: 1rem;
  border: 1px solid var(--lab-line);
  border-radius: 4px;
  background: var(--lab-wash);
  color: var(--lab-ink);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  white-space: pre-wrap;
}

.lab-answer-block {
  margin: 1.25rem 0;
}

.lab-answer-block label,
.lab-confidence legend {
  display: block;
  margin-bottom: 0.45rem;
  color: var(--lab-ink);
  font-weight: 700;
}

.lab-answer-block textarea {
  display: block;
  width: 100%;
  min-height: 108px;
  resize: vertical;
  padding: 0.85rem;
  border: 1px solid #aeb7c6;
  border-radius: 4px;
  background: var(--lab-paper);
  color: var(--lab-ink);
  line-height: 1.55;
}

.lab-answer-block textarea::placeholder {
  color: #7c8492;
}

.lab-confidence {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin: 1.25rem 0;
  padding: 0;
  border: 0;
}

.lab-confidence legend {
  flex: 0 0 100%;
}

.lab-confidence label {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.8rem;
  border: 1px solid var(--lab-line);
  border-radius: 4px;
  cursor: pointer;
}

.lab-self-check {
  margin: 1.5rem 0;
  padding: 1.1rem 0;
  border-top: 1px solid var(--lab-line);
  border-bottom: 1px solid var(--lab-line);
}

.lab-self-check h3 {
  margin: 0 0 0.65rem;
  font-size: 1rem;
}

.lab-self-check label {
  display: flex;
  min-height: 44px;
  align-items: flex-start;
  gap: 0.65rem;
  padding: 0.55rem 0;
  color: var(--lab-muted);
}

.lab-self-check input {
  width: 18px;
  height: 18px;
  margin-top: 0.2rem;
}

.lab-primary-button,
.lab-secondary-button,
.lab-text-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.65rem 1rem;
  border-radius: 4px;
  cursor: pointer;
  font-weight: 700;
}

.lab-primary-button {
  border: 1px solid var(--lab-cobalt);
  background: var(--lab-cobalt);
  color: #fff;
}

.lab-primary-button:hover {
  border-color: var(--lab-cobalt-dark);
  background: var(--lab-cobalt-dark);
}

.lab-secondary-button {
  border: 1px solid var(--lab-cobalt);
  background: var(--lab-paper);
  color: var(--lab-cobalt);
}

.lab-secondary-button:hover {
  background: var(--lab-cobalt-soft);
}

.lab-text-button {
  border: 1px solid transparent;
  background: transparent;
  color: var(--lab-cobalt);
}

.lab-text-button:hover {
  border-color: var(--lab-line);
  background: var(--lab-wash);
}

.lab-feedback {
  margin: 1.75rem 0;
  padding: 1.4rem 1.5rem;
  border-left: 5px solid var(--lab-cobalt);
  background: var(--lab-cobalt-soft);
}

.lab-feedback h3 {
  margin: 0 0 1rem;
  font-family: var(--font-display);
  font-size: 1.35rem;
  line-height: 1.25;
}

.lab-feedback blockquote {
  margin: 1rem 0;
  padding: 0.9rem 1rem;
  border-left: 3px solid var(--lab-yellow);
  background: var(--lab-paper);
  color: var(--lab-muted);
}

.lab-enhanced-answer {
  margin-top: 1.2rem;
  padding-top: 1.1rem;
  border-top: 1px solid #b8c6ed;
}

.lab-enhanced-answer > strong {
  color: var(--lab-cobalt-dark);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.lab-enhanced-answer p,
.lab-enhanced-answer ul {
  margin-bottom: 0;
}

.lab-final-response {
  margin-top: 1.5rem;
  padding-top: 0.25rem;
  border-top: 2px solid var(--lab-teal);
}

.lab-stage-actions,
.lab-export-actions {
  justify-content: space-between;
  gap: 0.75rem;
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--lab-line);
}

.lab-export-actions {
  justify-content: flex-start;
  flex-wrap: wrap;
}

.lab-export-note {
  color: var(--lab-muted);
  font-size: 0.82rem;
}

#lab-playbook {
  min-height: 560px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
}

.lab-provenance,
.lab-related {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 2px solid var(--lab-ink);
}

.lab-provenance h2,
.lab-related h2 {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: 1.25rem;
}

.lab-provenance p {
  max-width: 850px;
  color: var(--lab-muted);
  font-size: 0.85rem;
}

.lab-related ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.lab-related a {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  padding: 0.55rem 0.8rem;
  border: 1px solid var(--lab-line);
  border-radius: 4px;
  color: var(--lab-ink);
}

.lab-noscript {
  max-width: 1180px;
  margin: 1rem auto;
}

@media (max-width: 900px) {
  .lab-page-shell {
    padding-top: 0.5rem;
  }

  .lab-question-nav {
    grid-template-columns: repeat(4, minmax(44px, 1fr));
  }

  .lab-layout {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .lab-reference-sticky {
    position: static;
  }

  .lab-evidence-rail {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.45rem;
  }

  .lab-evidence-rail::before {
    display: none;
  }

  .lab-evidence-rail li {
    min-height: 52px;
    padding: 0.4rem;
    border: 1px solid var(--lab-line);
    border-radius: 4px;
  }

  .lab-evidence-rail li > span {
    width: 32px;
    height: 32px;
  }

  .lab-evidence-rail small {
    display: none;
  }

  .lab-reference-note {
    display: none;
  }
}

@media (max-width: 640px) {
  .lab-page-title {
    font-size: 2rem;
  }

  .lab-page-description {
    font-size: 1rem;
  }

  .lab-cover-figure,
  .lab-teaching-band,
  .lab-worked-example {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  .lab-four-grid,
  .lab-key-distinction,
  .lab-required-list {
    grid-template-columns: 1fr;
  }

  .lab-compare-lines p,
  .lab-glossary dl div {
    grid-template-columns: 1fr;
    gap: 0.2rem;
  }

  .lab-step-label {
    display: block;
  }

  .lab-step-label span {
    display: block;
    margin-top: 0.25rem;
  }

  .lab-stage-actions {
    align-items: stretch;
    flex-direction: column-reverse;
  }

  .lab-stage-actions button,
  .lab-export-actions button {
    width: 100%;
  }

  .lab-export-actions {
    flex-direction: column;
  }

  .lab-utility {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (max-width: 380px) {
  .lab-evidence-rail {
    grid-template-columns: 1fr;
  }

  .lab-question-nav {
    gap: 0.25rem;
    margin-right: 0;
    margin-left: 0;
    padding: 0.4rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .lab-stage {
    animation: none;
  }

  .grill-lab *,
  .grill-lab *::before,
  .grill-lab *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}

@media print {
  .site-header,
  .site-footer,
  .lab-page-header,
  .lab-utility,
  .lab-question-nav,
  .lab-js .lab-question-nav.js-only,
  .lab-reference,
  .lab-provenance,
  .lab-related,
  .lab-export-actions,
  .lab-js .lab-export-actions.js-only,
  .lab-stage-actions,
  .lab-js .lab-stage-actions.js-only,
  .lab-answer-block:has(#lab-transfer),
  .lab-export-note {
    display: none !important;
  }

  .lab-page-shell,
  .lab-layout {
    display: block;
    max-width: none;
    padding: 0;
  }

  .lab-stage {
    display: none !important;
  }

  .lab-finish {
    display: block !important;
  }

  #lab-playbook {
    min-height: 0;
    border: 0;
    overflow: visible;
    white-space: pre-wrap;
  }
}