:root {
  --paper: #f3f0e8;
  --paper-deep: #e8e2d6;
  --white: #fffdf8;
  --ink: #18252c;
  --muted: #5e6a6e;
  --navy: #173b4c;
  --teal: #1e6867;
  --rust: #a44a3f;
  --ochre: #a2762d;
  --line: #c9c1b3;
  --soft-line: #ded8cc;
  --shadow: 0 18px 48px rgb(29 43 48 / 8%);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  line-height: 1.55;
}

button,
input,
textarea {
  font: inherit;
}

a {
  color: inherit;
}

.site-header {
  width: min(1240px, calc(100% - 48px));
  height: 76px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  font-weight: 780;
  text-decoration: none;
}

.mark {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  background: var(--navy);
  color: var(--white);
  border-radius: 50%;
  font: 760 0.68rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
  letter-spacing: 0.08em;
}

nav {
  display: flex;
  gap: 28px;
  color: var(--muted);
  font-size: 0.9rem;
}

nav a {
  text-decoration: none;
}

nav a:hover,
nav a:focus-visible {
  color: var(--rust);
}

main {
  width: min(1240px, calc(100% - 48px));
  margin: 0 auto;
}

.hero {
  min-height: 650px;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: clamp(40px, 8vw, 110px);
  align-items: center;
  padding: 70px 0 86px;
}

.eyebrow,
.step-label,
.sidebar-label,
.figure-caption {
  margin: 0 0 14px;
  color: var(--rust);
  font: 760 0.72rem/1.4 ui-monospace, SFMono-Regular, Consolas, monospace;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

h1,
h2,
h3,
h4 {
  font-family: Georgia, "Times New Roman", serif;
}

h1 {
  max-width: 760px;
  margin: 0;
  font-size: clamp(3.15rem, 7vw, 6.8rem);
  line-height: 0.94;
  letter-spacing: -0.055em;
}

.lead {
  max-width: 650px;
  margin: 30px 0 0;
  color: var(--muted);
  font-size: clamp(1.08rem, 2vw, 1.35rem);
}

.hero-actions,
.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.button {
  min-height: 44px;
  border: 1px solid transparent;
  border-radius: 3px;
  padding: 11px 17px;
  cursor: pointer;
  font-weight: 720;
  text-decoration: none;
  transition:
    transform 140ms ease,
    background 140ms ease,
    border-color 140ms ease;
}

.button:hover:not(:disabled),
.button:focus-visible:not(:disabled) {
  transform: translateY(-1px);
}

.button.primary {
  background: var(--navy);
  color: var(--white);
}

.button.primary:hover:not(:disabled) {
  background: #0f3040;
}

.button.secondary {
  border-color: var(--line);
  background: transparent;
  color: var(--ink);
}

.button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

.trust-line {
  margin-top: 18px;
  color: var(--muted);
  font-size: 0.82rem;
}

.hero-figure {
  border: 1px solid var(--line);
  border-top: 12px solid var(--navy);
  background: var(--white);
  padding: 34px;
  box-shadow: var(--shadow);
}

.learner-state {
  display: grid;
  grid-template-columns: 46px 1fr;
  gap: 18px;
  align-items: center;
  min-height: 92px;
  border: 1px solid var(--soft-line);
  padding: 16px 18px;
}

.learner-state.emphasis {
  background: #e5efed;
  border-color: #9eb7b3;
}

.learner-state strong,
.learner-state small {
  display: block;
}

.learner-state strong {
  font: 700 1.25rem/1.1 Georgia, "Times New Roman", serif;
}

.learner-state small {
  margin-top: 6px;
  color: var(--muted);
}

.state-number {
  color: var(--rust);
  font: 750 0.8rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.connector {
  width: 1px;
  height: 22px;
  margin-left: 40px;
  background: var(--line);
}

.outcome-strip {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  margin-top: 26px;
  background: var(--line);
  border: 1px solid var(--line);
}

.outcome-strip span {
  min-width: 0;
  background: var(--paper);
  padding: 9px 6px;
  overflow-wrap: anywhere;
  text-align: center;
  font: 690 0.68rem/1.2 ui-monospace, SFMono-Regular, Consolas, monospace;
  text-transform: uppercase;
}

.principle-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.principle-grid article {
  min-width: 0;
  padding: 36px;
}

.principle-grid article + article {
  border-left: 1px solid var(--line);
}

.principle-grid article > span {
  color: var(--rust);
  font: 750 0.74rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.principle-grid h2 {
  margin: 20px 0 10px;
  font-size: 1.5rem;
}

.principle-grid p {
  margin: 0;
  color: var(--muted);
}

.lab-section,
.method-section {
  padding: 108px 0 20px;
}

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 50px;
  margin-bottom: 35px;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(2.3rem, 4.5vw, 4.2rem);
  line-height: 1;
  letter-spacing: -0.035em;
}

.section-heading > p {
  max-width: 520px;
  margin: 0;
  color: var(--muted);
}

.lab-shell {
  display: grid;
  grid-template-columns: 255px minmax(0, 1fr);
  min-height: 680px;
  border: 1px solid var(--line);
  background: var(--white);
  box-shadow: var(--shadow);
}

.lab-sidebar {
  padding: 30px 24px;
  background: var(--navy);
  color: #edf0ea;
}

.progress {
  margin: 0;
  padding: 0;
  list-style: none;
}

.progress li {
  display: grid;
  grid-template-columns: 26px 1fr;
  gap: 10px;
  align-items: center;
  min-height: 44px;
  color: #aebec2;
  font-size: 0.87rem;
}

.progress li span {
  display: grid;
  width: 24px;
  height: 24px;
  place-items: center;
  border: 1px solid #54717c;
  border-radius: 50%;
  font-size: 0.7rem;
}

.progress li.active {
  color: white;
  font-weight: 720;
}

.progress li.active span {
  border-color: #b4d5cf;
  background: #b4d5cf;
  color: var(--navy);
}

.progress li.complete {
  color: #b4d5cf;
}

.boundary {
  margin-top: 38px;
  padding-top: 20px;
  border-top: 1px solid #496570;
  font-size: 0.78rem;
}

.boundary p {
  margin: 8px 0 0;
  color: #afbec2;
}

.lab-main {
  position: relative;
  min-width: 0;
  padding: clamp(28px, 6vw, 64px);
}

.phase {
  display: none;
  max-width: 760px;
}

.phase.active {
  display: block;
}

.phase h3 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.3rem);
  line-height: 1.05;
  letter-spacing: -0.025em;
}

.phase-intro {
  max-width: 650px;
  margin: 18px 0 28px;
  color: var(--muted);
}

.task-card,
.selected-task,
.export-note,
.local-summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  border: 1px solid var(--line);
  background: var(--paper);
  padding: 22px;
}

.task-card h4,
.selected-task h4 {
  margin: 0;
  font-size: 1.28rem;
}

.task-card p:not(.eyebrow),
.selected-task p {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 0.86rem;
}

.divider {
  display: flex;
  align-items: center;
  gap: 14px;
  margin: 24px 0;
  color: var(--muted);
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.divider::before,
.divider::after {
  height: 1px;
  flex: 1;
  background: var(--soft-line);
  content: "";
}

.file-drop {
  display: grid;
  min-height: 120px;
  place-items: center;
  align-content: center;
  border: 1px dashed #9a9388;
  padding: 20px;
  cursor: pointer;
  text-align: center;
}

.file-drop:hover,
.file-drop:focus-within {
  border-color: var(--teal);
  background: #edf3f0;
}

.file-drop input {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
}

.file-drop span {
  margin-top: 4px;
  color: var(--muted);
  font-size: 0.8rem;
}

.field,
.slider-field {
  display: grid;
  gap: 7px;
  margin-top: 22px;
}

.field > span,
.slider-field label {
  font-weight: 720;
}

.field input,
.field textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 0;
  background: #fff;
  color: var(--ink);
  padding: 12px 13px;
}

.field input:focus,
.field textarea:focus {
  border-color: var(--teal);
  outline: 2px solid rgb(30 104 103 / 15%);
}

.field small {
  color: var(--muted);
}

.assessment {
  display: grid;
  gap: 22px;
}

.question {
  border-top: 1px solid var(--line);
  padding-top: 20px;
}

.question legend {
  max-width: 720px;
  padding: 0;
  font-weight: 720;
}

.options {
  display: grid;
  gap: 8px;
  margin-top: 13px;
}

.option,
.check-field {
  display: flex;
  align-items: start;
  gap: 10px;
  border: 1px solid var(--soft-line);
  padding: 11px 12px;
  cursor: pointer;
}

.option:hover,
.option:focus-within,
.check-field:hover {
  background: #edf3f0;
  border-color: #9db4af;
}

.option input,
.check-field input {
  margin-top: 4px;
  accent-color: var(--teal);
}

.numeric-answer {
  width: min(260px, 100%);
  margin-top: 12px;
  border: 1px solid var(--line);
  padding: 10px;
}

.tutor-fields {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}

.prompt-box {
  margin-top: 24px;
  border: 1px solid var(--line);
  background: #172a33;
  color: #edf0e9;
}

.prompt-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid #3a4e56;
  padding: 11px 16px;
}

.text-button {
  border: 0;
  background: none;
  color: #b6d7d2;
  cursor: pointer;
}

.prompt-box pre {
  max-height: 330px;
  margin: 0;
  overflow: auto;
  padding: 18px;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  font: 0.82rem/1.6 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.timer-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-top: 18px;
  border: 1px solid var(--line);
  padding: 14px 16px;
}

.timer-row strong,
.timer-label {
  display: block;
}

.timer-row strong {
  margin-top: 3px;
  font: 750 1.45rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.timer-label {
  color: var(--muted);
  font-size: 0.75rem;
}

.check-field {
  margin-top: 18px;
}

.slider-field {
  border-bottom: 1px solid var(--soft-line);
  padding: 18px 0;
}

.slider-field label {
  display: flex;
  justify-content: space-between;
}

.slider-field output {
  color: var(--rust);
  font: 750 1rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.slider-field input {
  width: 100%;
  accent-color: var(--teal);
}

.local-summary {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  align-items: stretch;
}

.summary-metric {
  min-width: 0;
  text-align: center;
}

.summary-metric strong,
.summary-metric span {
  display: block;
}

.summary-metric strong {
  font: 700 2rem/1 Georgia, "Times New Roman", serif;
}

.summary-metric span {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.75rem;
  text-transform: uppercase;
}

.export-note {
  display: block;
  margin-top: 20px;
  border-left: 4px solid var(--ochre);
}

.export-note p {
  margin: 6px 0 0;
}

.lab-message {
  min-height: 24px;
  margin: 18px 0 0;
  color: var(--rust);
  font-size: 0.86rem;
}

.method-section {
  padding-bottom: 100px;
}

.method-table {
  border-top: 4px solid var(--navy);
  border-bottom: 1px solid var(--line);
}

.method-row {
  display: grid;
  grid-template-columns: 0.7fr 1.2fr 1.4fr;
  gap: 24px;
  min-width: 0;
  border-top: 1px solid var(--line);
  padding: 18px 12px;
}

.method-row:first-child {
  border-top: 0;
}

.method-row.header {
  color: var(--muted);
  font: 720 0.7rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

footer {
  display: flex;
  width: min(1240px, calc(100% - 48px));
  min-height: 100px;
  align-items: center;
  gap: 22px;
  margin: 0 auto;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.83rem;
}

footer strong {
  color: var(--ink);
}

footer a {
  margin-left: auto;
}

@media (max-width: 900px) {
  .hero,
  .lab-shell {
    grid-template-columns: 1fr;
  }

  .hero {
    padding-top: 60px;
  }

  .principle-grid {
    grid-template-columns: 1fr;
  }

  .principle-grid article + article {
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .lab-sidebar {
    padding: 20px;
  }

  .progress {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 5px;
  }

  .progress li {
    display: block;
    min-width: 0;
    overflow: hidden;
    text-align: center;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .progress li span {
    margin: 0 auto 5px;
  }

  .boundary {
    display: none;
  }
}

@media (max-width: 700px) {
  .site-header,
  main,
  footer {
    width: min(100% - 24px, 1240px);
  }

  nav a:not(:last-child) {
    display: none;
  }

  .hero {
    min-height: auto;
  }

  h1 {
    font-size: clamp(3rem, 16vw, 5rem);
  }

  .section-heading {
    display: block;
  }

  .section-heading > p {
    margin-top: 18px;
  }

  .lab-section,
  .method-section {
    padding-top: 74px;
  }

  .progress li {
    font-size: 0;
  }

  .progress li span {
    font-size: 0.68rem;
  }

  .lab-main {
    padding: 28px 18px;
  }

  .task-card,
  .selected-task,
  .timer-row {
    display: block;
  }

  .task-card .button,
  .timer-row .button {
    margin-top: 16px;
  }

  .tutor-fields,
  .local-summary {
    grid-template-columns: 1fr;
  }

  .method-row {
    grid-template-columns: 1fr;
    gap: 5px;
  }

  .method-row.header {
    display: none;
  }

  footer {
    display: grid;
    gap: 8px;
    padding: 22px 0;
  }

  footer a {
    margin-left: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .button {
    transition: none;
  }
}