:root {
  --ink: #18382c;
  --muted: #687269;
  --paper: #f1eee5;
  --surface: #fbf8f0;
  --line: #d4d1c5;
  --line-strong: #969d92;
  --blue: #315e46;
  --blue-dark: #173b2d;
  --blue-soft: #dfe8dd;
  --yellow: #e9c565;
  --focus-warm: #ed826b;
  --green: #315e46;
  --green-soft: #e3ece0;
  --orange-soft: #fff0d8;
  --red: #99382d;
  --red-soft: #fae8e4;
  --sans: Inter, "PingFang SC", "Noto Sans CJK SC", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: "SFMono-Regular", "Roboto Mono", "Cascadia Mono", ui-monospace, monospace;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 62px;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--sans);
  line-height: 1.5;
}

button,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 100;
  padding: 10px 14px;
  color: #fff;
  background: var(--blue-dark);
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

:focus-visible {
  outline: 3px solid var(--blue);
  outline-offset: 3px;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

.demo-hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 270px;
  gap: 44px;
  align-items: end;
  max-width: 1440px;
  margin: 0 auto;
  padding: 20px 40px 18px;
  border-bottom: 1px solid var(--line-strong);
}

.eyebrow,
.section-index,
.field-label,
.metric-label,
.flow-kicker {
  margin: 0;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 750;
  letter-spacing: 0.085em;
  text-transform: uppercase;
}

h1 {
  margin: 5px 0 8px;
  font-size: clamp(2.4rem, 3.9vw, 3.8rem);
  font-weight: 700;
  letter-spacing: -0.06em;
  line-height: 0.98;
}

.hero-story {
  max-width: 920px;
  margin-bottom: 10px;
  color: #41443e;
  font-size: clamp(0.92rem, 1.35vw, 1.05rem);
  line-height: 1.55;
}

.hero-facts {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.hero-facts li {
  padding: 6px 10px;
  color: var(--blue-dark);
  background: var(--blue-soft);
  border-left: 3px solid var(--blue);
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 700;
}

.hero-action {
  padding-left: 22px;
  border-left: 1px solid var(--line);
}

.hero-action p {
  margin-bottom: 8px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 700;
}

.hero-action > span {
  display: block;
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.72rem;
}

.demo-button {
  width: 100%;
  min-height: 50px;
  padding: 12px 15px;
  color: #fff;
  background: var(--blue);
  border: 1px solid var(--blue-dark);
  font-weight: 750;
  text-align: left;
}

.demo-button span {
  float: right;
}

.demo-button:hover {
  background: var(--blue-dark);
}

.section-nav {
  position: sticky;
  top: 0;
  z-index: 20;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  max-width: 1440px;
  margin: 0 auto;
  background: rgb(245 242 232 / 96%);
  border-bottom: 1px solid var(--line-strong);
  backdrop-filter: blur(12px);
}

.section-nav a {
  min-height: 52px;
  padding: 16px 14px;
  color: var(--ink);
  border-right: 1px solid var(--line);
  font-family: var(--mono);
  font-size: 0.71rem;
  font-weight: 700;
  text-align: center;
  text-decoration: none;
}

.section-nav a:last-child {
  border-right: 0;
}

.section-nav a:hover,
.section-nav a:focus-visible {
  color: #fff;
  background: var(--blue);
}

main {
  max-width: 1440px;
  margin: 0 auto;
}

.screen {
  min-height: 720px;
  padding: 26px 40px 48px;
  border-bottom: 1px solid var(--line-strong);
}

.challenge-screen {
  min-height: 760px;
  overflow: hidden;
  background:
    radial-gradient(circle at 14% 22%, rgb(255 255 255 / 72%) 0 7%, transparent 34%),
    linear-gradient(135deg, #e8ebe1 0%, #f2efe6 58%, #e4e8df 100%);
}

.challenge-heading {
  position: relative;
  z-index: 2;
}

.challenge-desk {
  position: relative;
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 38px;
  max-width: 1120px;
  margin: 20px auto 0;
  padding: 26px 18px 34px;
}

.challenge-desk::before {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(90deg, rgb(49 94 70 / 3%) 1px, transparent 1px),
    linear-gradient(rgb(49 94 70 / 3%) 1px, transparent 1px);
  background-size: 24px 24px;
  border-radius: 30px;
  content: "";
  pointer-events: none;
}

.challenge-note {
  position: relative;
  align-self: start;
  margin-top: 72px;
  padding: 28px 24px 32px;
  background: #ece0a9;
  border: 1px solid #cbbd7e;
  box-shadow: 0 14px 28px rgb(51 60 45 / 13%);
  transform: rotate(-2.4deg);
}

.challenge-note::before {
  position: absolute;
  top: -12px;
  left: 50%;
  width: 72px;
  height: 24px;
  background: rgb(255 250 225 / 68%);
  border: 1px solid rgb(181 169 132 / 38%);
  content: "";
  transform: translateX(-50%) rotate(1deg);
}

.challenge-note span,
.challenge-note small,
.challenge-note strong {
  display: block;
}

.challenge-note span {
  margin-bottom: 18px;
  color: #6c694d;
  font-family: var(--mono);
  font-size: 0.66rem;
  font-weight: 800;
  letter-spacing: 0.08em;
}

.challenge-note strong {
  padding: 8px 0;
  border-bottom: 1px dashed rgb(74 82 61 / 26%);
  font-size: 0.92rem;
}

.challenge-note small {
  margin-top: 18px;
  color: #68664e;
  font-size: 0.72rem;
  line-height: 1.65;
}

.challenge-sheet {
  position: relative;
  min-height: 540px;
  padding: 30px 36px 34px;
  background:
    linear-gradient(90deg, transparent 49.82%, rgb(75 88 77 / 7%) 50%, transparent 50.18%),
    linear-gradient(#fcfaf3, #f6f2e8);
  border: 1px solid #c9c7bc;
  border-radius: 4px 18px 12px 5px;
  box-shadow:
    0 24px 45px rgb(49 60 51 / 16%),
    4px 5px 0 #dfe1d5;
  transform: rotate(0.45deg);
}

.challenge-sheet::after {
  position: absolute;
  top: -14px;
  right: 72px;
  width: 94px;
  height: 28px;
  background: rgb(231 221 191 / 65%);
  border: 1px solid rgb(164 153 123 / 28%);
  content: "";
  transform: rotate(-1.2deg);
}

.round-progress {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0;
  margin: 0 0 30px;
  padding: 0;
  list-style: none;
  border-bottom: 1px solid var(--line);
}

.round-progress li {
  display: flex;
  gap: 8px;
  align-items: center;
  min-height: 42px;
  color: #92978e;
  font-family: var(--mono);
  font-size: 0.64rem;
  font-weight: 750;
}

.round-progress li span {
  display: grid;
  width: 22px;
  height: 22px;
  place-items: center;
  border: 1px solid #bfc3ba;
  border-radius: 50%;
}

.round-progress li[aria-current="step"] {
  color: var(--blue-dark);
}

.round-progress li[aria-current="step"] span {
  color: #fff;
  background: var(--blue);
  border-color: var(--blue);
}

.round-progress li.is-complete span {
  color: var(--blue-dark);
  background: var(--blue-soft);
  border-color: #90a691;
}

.challenge-round[hidden],
.challenge-complete[hidden] {
  display: none;
}

.round-kicker {
  margin-bottom: 8px;
  color: #758179;
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 800;
  letter-spacing: 0.08em;
}

.challenge-round h3,
.challenge-complete h3 {
  max-width: 760px;
  margin: 0 0 9px;
  font-size: clamp(1.55rem, 2.6vw, 2.35rem);
  font-weight: 650;
  letter-spacing: -0.04em;
  line-height: 1.14;
}

.round-copy {
  margin-bottom: 20px;
  color: var(--muted);
  font-size: 0.83rem;
}

.strategy-choices,
.reason-choices {
  display: grid;
  gap: 10px;
}

.strategy-choices {
  grid-template-columns: repeat(3, 1fr);
}

.strategy-choices button,
.reason-choices button {
  min-height: 72px;
  padding: 14px 16px;
  color: var(--ink);
  background: rgb(255 255 255 / 60%);
  border: 1px solid #bdc3ba;
  border-radius: 10px;
  text-align: left;
  transition: transform 150ms ease, border-color 150ms ease, box-shadow 150ms ease;
}

.strategy-choices button:hover,
.reason-choices button:hover {
  border-color: var(--blue);
  box-shadow: 0 7px 16px rgb(40 65 49 / 9%);
  transform: translateY(-2px);
}

.strategy-choices button.is-selected,
.reason-choices button.is-selected {
  background: var(--blue-soft);
  border-color: var(--blue);
  box-shadow: inset 0 0 0 1px var(--blue);
}

.strategy-choices span,
.strategy-choices small {
  display: block;
}

.strategy-choices span {
  font-weight: 750;
}

.strategy-choices small {
  margin-top: 5px;
  color: var(--muted);
  font-size: 0.68rem;
  line-height: 1.45;
}

.round-feedback {
  min-height: 52px;
  margin: 16px 0 14px;
  padding: 12px 14px;
  color: #3f5549;
  background: rgb(224 232 221 / 60%);
  border-left: 3px solid #8fa28f;
  font-size: 0.78rem;
}

.round-next,
.complete-actions button,
.complete-actions a {
  min-height: 46px;
  padding: 11px 16px;
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 750;
}

.round-next {
  color: #fff;
  background: var(--blue);
  border: 1px solid var(--blue-dark);
}

.round-next:hover:not(:disabled) {
  background: var(--blue-dark);
}

.round-next:disabled {
  color: #8a8e88;
  background: #e1e1da;
  border-color: #cbccc5;
  cursor: not-allowed;
}

.sample-envelopes {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 22px;
  padding: 7px 10px 9px;
}

.sample-envelope {
  position: relative;
  min-height: 222px;
  padding: 24px 24px 20px;
  color: var(--ink);
  background: #ebe3cf;
  border: 1px solid #beb6a3;
  box-shadow: 0 12px 22px rgb(48 57 48 / 12%);
  text-align: left;
  transition: transform 180ms ease, box-shadow 180ms ease, border-color 180ms ease;
}

.sample-envelope-a {
  transform: rotate(-1.8deg);
}

.sample-envelope-b {
  background: #dce5d7;
  transform: rotate(1.5deg);
}

.sample-envelope::before {
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  height: 52px;
  background: linear-gradient(155deg, transparent 49%, rgb(83 84 67 / 9%) 50%, transparent 51%);
  content: "";
  pointer-events: none;
}

.sample-envelope:hover {
  border-color: var(--blue);
  box-shadow: 0 18px 28px rgb(41 59 46 / 18%);
  transform: rotate(0deg) translateY(-4px);
}

.sample-envelope.is-selected {
  border-color: var(--blue);
  box-shadow: 0 0 0 2px var(--blue), 0 18px 28px rgb(41 59 46 / 18%);
  transform: rotate(0deg) translateY(-4px);
}

.sample-envelope.is-correct::after,
.reason-choices button.is-correct::after,
.sample-envelope.is-wrong::after,
.reason-choices button.is-wrong::after {
  float: right;
  font-family: var(--mono);
  font-size: 0.62rem;
  font-weight: 800;
}

.sample-envelope.is-correct::after {
  color: var(--green);
  content: "真实更高";
}

.reason-choices button.is-correct::after {
  color: var(--green);
  content: "证据支持";
}

.sample-envelope.is-wrong::after,
.reason-choices button.is-wrong::after {
  color: var(--red);
  content: "证据不支持";
}

.envelope-label,
.choose-mark {
  display: block;
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 800;
  letter-spacing: 0.06em;
}

.sample-envelope > strong {
  display: block;
  margin: 8px 0 12px;
  font-size: 1.38rem;
}

.envelope-stats,
.envelope-stats > span {
  display: block;
}

.envelope-stats > span {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 12px;
  padding: 6px 0;
  border-bottom: 1px dashed rgb(65 74 65 / 24%);
  font-size: 0.71rem;
}

.envelope-stats b {
  font-family: var(--mono);
  font-weight: 800;
}

.choose-mark {
  margin-top: 14px;
  color: var(--blue-dark);
}

.reason-choices button {
  position: relative;
  padding-right: 100px;
}

.challenge-complete {
  padding: 8px 0 4px;
}

.challenge-complete > p:not(.round-kicker):not(.claim-boundary) {
  max-width: 760px;
  color: #3f5047;
  font-size: 0.85rem;
  line-height: 1.7;
}

.final-result-strip {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  margin: 24px 0 20px;
  background: #aeb7ae;
  border: 1px solid #aeb7ae;
}

.final-result-strip div {
  min-height: 92px;
  padding: 16px;
  background: #f5f1e6;
}

.final-result-strip span,
.final-result-strip strong {
  display: block;
}

.final-result-strip span {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.65rem;
}

.final-result-strip strong {
  margin-top: 8px;
  font-family: var(--mono);
  font-size: 1rem;
}

.claim-boundary {
  margin: 18px 0;
  padding: 12px 14px;
  color: #6d2d24;
  background: var(--red-soft);
  border-left: 3px solid var(--red);
  font-size: 0.75rem;
}

.complete-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.complete-actions button {
  color: var(--ink);
  background: transparent;
  border: 1px solid #96a096;
}

.complete-actions a {
  display: inline-flex;
  align-items: center;
  color: #fff;
  background: var(--blue);
  border: 1px solid var(--blue-dark);
  text-decoration: none;
}

.section-heading {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 470px);
  gap: 30px;
  align-items: end;
  margin-bottom: 15px;
}

h2 {
  margin: 5px 0 0;
  font-size: clamp(1.85rem, 2.7vw, 2.8rem);
  font-weight: 700;
  letter-spacing: -0.05em;
  line-height: 1.05;
}

.section-intro {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
  text-align: right;
}

.qa-stage {
  display: grid;
  grid-template-columns: minmax(390px, 0.9fr) minmax(490px, 1.1fr);
  min-height: 475px;
  background: var(--surface);
  border: 1px solid var(--line-strong);
}

.sample-side {
  padding: 18px;
  border-right: 1px solid var(--line-strong);
}

.sample-toolbar {
  display: flex;
  gap: 16px;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}

.sample-toolbar label {
  font-size: 0.76rem;
  font-weight: 750;
}

.sample-counter {
  color: var(--blue-dark);
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 750;
}

select {
  width: 100%;
  min-height: 44px;
  padding: 0 38px 0 11px;
  color: var(--ink);
  background: #fff;
  border: 1px solid var(--line-strong);
  border-radius: 0;
}

.image-stage {
  display: grid;
  grid-template-rows: minmax(320px, 1fr) auto;
  margin: 12px 0 0;
  background: #e8e7e0;
  border: 1px solid var(--line);
}

.image-stage img {
  width: 100%;
  height: 100%;
  min-height: 320px;
  max-height: 350px;
  padding: 13px;
  object-fit: contain;
}

.image-stage figcaption {
  padding: 8px 10px;
  color: var(--muted);
  background: var(--surface);
  border-top: 1px solid var(--line);
  font-size: 0.72rem;
}

.question-side {
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
}

.task-label {
  display: flex;
  gap: 14px;
  align-items: center;
  padding: 12px 28px;
  color: var(--blue-dark);
  background: var(--blue-soft);
  border-bottom: 1px solid #bdccef;
}

.task-label span {
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 750;
  text-transform: uppercase;
}

.task-label strong {
  font-size: 0.84rem;
}

.question-block {
  padding: 16px 26px 13px;
}

.question-block h3 {
  max-width: 780px;
  margin: 7px 0 12px;
  font-size: clamp(1.35rem, 1.9vw, 1.9rem);
  font-weight: 650;
  letter-spacing: -0.035em;
  line-height: 1.2;
}

.choices {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.choice-item {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  align-items: start;
  padding: 8px 0;
  border-bottom: 1px solid var(--line);
}

.choice-label {
  color: var(--blue);
  font-family: var(--mono);
  font-size: 0.8rem;
  font-weight: 800;
}

.choice-copy {
  font-size: 0.92rem;
}

.original-question {
  margin-top: 12px;
  color: var(--muted);
  font-size: 0.72rem;
}

.original-question summary {
  width: fit-content;
  padding: 6px 0;
  color: var(--blue-dark);
  font-family: var(--mono);
  font-weight: 700;
  cursor: pointer;
}

.original-question p {
  margin: 8px 0 4px;
}

.original-question ol {
  margin: 0;
  padding-left: 22px;
}

.answer-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border-top: 1px solid var(--line-strong);
}

.answer-panel {
  min-height: 108px;
  padding: 13px 18px;
}

.answer-panel + .answer-panel {
  border-left: 1px solid var(--line-strong);
}

.ground-truth-panel {
  background: var(--green-soft);
}

.prediction-panel[data-state="waiting"] {
  background: var(--orange-soft);
}

.prediction-panel[data-state="available"] {
  background: var(--blue-soft);
}

.answer-value {
  margin: 10px 0 6px;
  font-size: 1rem;
  font-weight: 750;
}

.answer-note {
  margin: 0;
  color: var(--muted);
  font-size: 0.7rem;
}

.research-screen {
  background: var(--surface);
}

.research-flow {
  display: grid;
  grid-template-columns: minmax(130px, 0.7fr) 36px minmax(230px, 1.2fr) 36px minmax(170px, 0.9fr) 36px minmax(145px, 0.75fr);
  gap: 8px;
  align-items: center;
  padding: 24px;
  background: var(--paper);
  border-top: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
}

.flow-node {
  min-height: 124px;
  padding: 18px;
  background: var(--surface);
  border-left: 4px solid var(--line-strong);
}

.flow-node strong,
.flow-node small {
  display: block;
}

.flow-node strong {
  margin: 8px 0 4px;
  font-size: clamp(1rem, 1.6vw, 1.35rem);
  letter-spacing: -0.025em;
}

.flow-node small {
  color: var(--muted);
  font-size: 0.72rem;
}

.source-node {
  border-left-color: var(--yellow);
}

.selected-node {
  border-left-color: var(--blue);
}

.budget-node {
  border-left-color: #7b6bd6;
}

.evaluation-node {
  border-left-color: var(--green);
}

.flow-arrow {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 1.5rem;
  text-align: center;
}

.flow-branch {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 8px;
  align-items: center;
}

.flow-vs {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 800;
}

.research-lower {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(300px, 0.7fr);
  gap: 42px;
  margin-top: 30px;
}

.status-list {
  margin-top: 12px;
  border-top: 1px solid var(--line-strong);
}

.status-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(180px, auto);
  gap: 20px;
  align-items: center;
  padding: 11px 0;
  border-bottom: 1px solid var(--line);
}

.status-copy strong,
.status-copy small {
  display: block;
}

.status-copy strong {
  font-size: 0.84rem;
}

.status-copy small {
  margin-top: 2px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.61rem;
  overflow-wrap: anywhere;
}

.status-value {
  justify-self: end;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 800;
  text-align: right;
}

.tone-complete .status-value,
.tone-complete .roadmap-state {
  color: var(--green);
}

.tone-ready .status-value,
.tone-ready .roadmap-state {
  color: #945700;
}

.no-claim {
  align-self: start;
  padding: 24px;
  color: #fff;
  background: #282a26;
}

.no-claim span,
.no-claim strong {
  display: block;
}

.no-claim span {
  color: #b9bdb2;
  font-family: var(--mono);
  font-size: 0.68rem;
  text-transform: uppercase;
}

.no-claim strong {
  margin: 10px 0;
  font-size: 1.3rem;
  line-height: 1.3;
}

.no-claim p {
  margin: 0;
  color: #cdd0c8;
  font-size: 0.78rem;
}

.result-card {
  padding: 22px;
}

.result-card > strong {
  font-size: 1.08rem;
}

.result-metrics {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  margin: 16px 0;
  background: rgb(255 255 255 / 16%);
}

.result-metrics .metric-item {
  min-height: 82px;
  padding: 12px;
  background: #343733;
}

.result-metrics .metric-label {
  color: #aeb4aa;
}

.result-metrics .metric-value {
  margin-top: 8px;
  color: #fff;
  font-size: 1rem;
}

.seed-results {
  margin-bottom: 14px;
  border-top: 1px solid rgb(255 255 255 / 18%);
}

.seed-row {
  display: grid;
  grid-template-columns: 0.75fr 1fr 1.18fr 0.65fr;
  gap: 8px;
  padding: 8px 0;
  border-bottom: 1px solid rgb(255 255 255 / 13%);
  font-family: var(--mono);
  font-size: 0.62rem;
}

.seed-id {
  color: #aeb4aa;
}

.seed-delta {
  color: #ffb9ad;
  text-align: right;
}

.training-proof {
  display: grid;
  grid-template-columns: minmax(270px, 0.55fr) minmax(0, 1.45fr);
  border: 1px solid var(--line-strong);
}

.proof-lead {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 18px;
  align-content: start;
  padding: 28px;
  color: #fff;
  background: var(--green);
}

.proof-mark {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  color: var(--green);
  background: #fff;
  border-radius: 50%;
  font-size: 1.3rem;
  font-weight: 800;
}

.proof-lead p,
.proof-lead strong,
.proof-lead span {
  display: block;
}

.proof-lead p {
  margin-bottom: 10px;
  color: #bfe1cd;
  font-family: var(--mono);
  font-size: 0.68rem;
  text-transform: uppercase;
}

.proof-lead strong {
  font-size: 1.35rem;
  line-height: 1.25;
}

.proof-lead span {
  margin-top: 10px;
  color: #d6e9de;
  font-size: 0.78rem;
}

.metric-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
}

.metric-item {
  min-height: 135px;
  padding: 18px;
  background: var(--surface);
}

.metric-value {
  margin: 14px 0 0;
  font-family: var(--mono);
  font-size: clamp(1rem, 1.5vw, 1.25rem);
  font-weight: 800;
  letter-spacing: -0.025em;
  overflow-wrap: anywhere;
}

.evidence-screen {
  background: #ece9df;
}

.evidence-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(380px, 0.8fr);
  gap: 1px;
  background: var(--line-strong);
  border: 1px solid var(--line-strong);
}

.technical-details,
.roadmap-panel {
  padding: 24px;
  background: var(--surface);
}

.technical-details h3,
.roadmap-panel h3 {
  margin-bottom: 16px;
  font-size: 1rem;
}

.technical-details dl {
  display: grid;
  grid-template-columns: 160px minmax(0, 1fr);
  margin: 0;
}

.technical-details dt,
.technical-details dd {
  margin: 0;
  padding: 9px 0;
  border-bottom: 1px solid var(--line);
  font-size: 0.72rem;
}

.technical-details dt {
  color: var(--muted);
}

.technical-details dd {
  overflow-wrap: anywhere;
}

.technical-details code,
.roadmap code {
  font-family: var(--mono);
  font-size: 0.65rem;
}

.evidence-boundary {
  margin: 18px 0 0;
  padding: 13px;
  color: #6d2d24;
  background: var(--red-soft);
  border-left: 3px solid var(--red);
  font-size: 0.72rem;
}

.roadmap {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.roadmap-item {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(170px, 0.8fr);
  gap: 7px 18px;
  padding: 13px 0;
  border-bottom: 1px solid var(--line);
}

.roadmap-heading {
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr);
  gap: 8px;
}

.roadmap-number {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.67rem;
}

.roadmap-heading strong {
  font-size: 0.76rem;
}

.roadmap-state {
  justify-self: end;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.62rem;
  font-weight: 800;
  text-align: right;
  overflow-wrap: anywhere;
}

.roadmap-source,
.roadmap-detail {
  grid-column: 1 / -1;
  margin: 0 0 0 36px;
  color: var(--muted);
  overflow-wrap: anywhere;
}

.roadmap-detail {
  font-family: var(--mono);
  font-size: 0.61rem;
}

footer {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  max-width: 1440px;
  margin: 0 auto;
  padding: 22px 40px 42px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.62rem;
}

footer p {
  margin: 0;
  overflow-wrap: anywhere;
}

footer a {
  color: inherit;
  text-underline-offset: 3px;
}

footer a:hover,
footer a:focus-visible {
  color: var(--blue-dark);
}

footer p:last-child {
  text-align: right;
}

.demo-controller {
  position: fixed;
  right: 24px;
  bottom: 24px;
  left: 24px;
  z-index: 50;
  display: grid;
  grid-template-columns: minmax(260px, 1fr) minmax(240px, 0.7fr) auto;
  gap: 22px;
  align-items: center;
  max-width: 960px;
  margin: 0 auto;
  padding: 14px 16px;
  color: #fff;
  background: rgb(26 31 27 / 97%);
  border: 1px solid rgb(255 255 255 / 14%);
  border-radius: 18px;
  box-shadow:
    0 18px 52px rgb(17 20 17 / 24%),
    inset 0 1px 0 rgb(255 255 255 / 7%);
  backdrop-filter: blur(14px);
}

.demo-controller[hidden] {
  display: none;
}

.demo-controller-copy span,
.demo-controller-copy strong {
  display: block;
}

.demo-controller-copy span {
  color: #b8bdb5;
  font-family: var(--mono);
  font-size: 0.65rem;
}

.demo-controller-copy strong {
  margin-top: 3px;
  font-size: 0.78rem;
}

.demo-progress-wrap {
  display: grid;
  grid-template-columns: 1fr 34px;
  gap: 10px;
  align-items: center;
}

progress {
  width: 100%;
  height: 8px;
  appearance: none;
  overflow: hidden;
  border-radius: 999px;
}

progress::-webkit-progress-bar {
  background: #4d524a;
  border-radius: 999px;
}

progress::-webkit-progress-value {
  background: var(--focus-warm);
  border-radius: 999px;
}

.demo-progress-wrap span {
  font-family: var(--mono);
  font-size: 0.68rem;
}

.demo-controller button {
  min-height: 40px;
  padding: 0 14px;
  color: #fff;
  background: transparent;
  border: 1px solid rgb(255 255 255 / 24%);
  border-radius: 10px;
}

.demo-controller button:hover {
  background: #343934;
}

.demo-active {
  position: relative;
  z-index: 4;
  border-radius: 18px;
  outline: 2px solid rgb(231 189 63 / 88%);
  outline-offset: 7px;
  box-shadow:
    0 0 26px rgb(231 189 63 / 22%),
    0 0 0 9999px rgb(23 25 22 / 38%);
  transition:
    outline-color 220ms cubic-bezier(.2, .72, .2, 1),
    box-shadow 220ms cubic-bezier(.2, .72, .2, 1);
}

.fatal-error {
  position: fixed;
  inset: 20px;
  z-index: 100;
  padding: 24px;
  color: #fff;
  background: #7d251c;
  border: 2px solid #fff;
  font-family: var(--mono);
}

@media (max-width: 1050px) {
  .challenge-desk {
    grid-template-columns: 170px minmax(0, 1fr);
    gap: 22px;
  }

  .challenge-note {
    padding: 24px 18px;
  }

  .strategy-choices {
    grid-template-columns: 1fr;
  }

  .strategy-choices button {
    min-height: 62px;
  }

  .qa-stage,
  .training-proof {
    grid-template-columns: 1fr;
  }

  .sample-side {
    border-right: 0;
    border-bottom: 1px solid var(--line-strong);
  }

  .research-flow {
    grid-template-columns: 1fr;
  }

  .flow-arrow {
    transform: rotate(90deg);
  }

  .metric-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (max-width: 760px) {
  html {
    scroll-padding-top: 64px;
  }

  .demo-hero {
    grid-template-columns: 1fr;
    gap: 20px;
    padding: 24px 18px 22px;
  }

  .hero-action {
    padding: 16px 0 0;
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  h1 {
    font-size: clamp(2rem, 9.2vw, 2.25rem);
    line-height: 1.02;
  }

  .section-nav a {
    min-width: 0;
    min-height: 60px;
    padding: 12px 4px;
    font-size: 0.59rem;
    line-height: 1.3;
  }

  .screen {
    min-height: 0;
    padding: 32px 18px 42px;
  }

  .challenge-screen {
    padding-right: 14px;
    padding-left: 14px;
  }

  .challenge-desk {
    display: block;
    margin-top: 4px;
    padding: 12px 0 0;
  }

  .challenge-desk::before {
    display: none;
  }

  .challenge-note {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 5px 10px;
    margin: 0 10px -12px;
    padding: 18px 16px 25px;
    transform: rotate(-0.7deg);
  }

  .challenge-note::before {
    width: 58px;
    height: 18px;
  }

  .challenge-note span,
  .challenge-note small {
    grid-column: 1 / -1;
  }

  .challenge-note span {
    margin-bottom: 5px;
  }

  .challenge-note strong {
    font-size: 0.78rem;
  }

  .challenge-note small {
    margin-top: 6px;
  }

  .challenge-sheet {
    min-height: 0;
    padding: 28px 18px 26px;
    border-radius: 4px 12px 10px 5px;
    transform: none;
  }

  .challenge-sheet::after {
    right: 28px;
    width: 68px;
  }

  .round-progress {
    margin-bottom: 22px;
  }

  .round-progress li {
    display: grid;
    justify-items: center;
    gap: 3px;
    padding: 7px 2px;
    font-size: 0.55rem;
    text-align: center;
  }

  .challenge-round h3,
  .challenge-complete h3 {
    font-size: 1.7rem;
  }

  .strategy-choices {
    grid-template-columns: 1fr;
  }

  .sample-envelopes,
  .final-result-strip {
    grid-template-columns: 1fr;
  }

  .sample-envelopes {
    gap: 12px;
    padding: 4px 0;
  }

  .sample-envelope,
  .sample-envelope-a,
  .sample-envelope-b,
  .sample-envelope:hover,
  .sample-envelope.is-selected {
    min-height: 0;
    transform: none;
  }

  .reason-choices button {
    padding-right: 16px;
  }

  .sample-envelope.is-correct::after,
  .reason-choices button.is-correct::after,
  .sample-envelope.is-wrong::after,
  .reason-choices button.is-wrong::after {
    display: block;
    float: none;
    margin-top: 8px;
  }

  .section-heading {
    grid-template-columns: 1fr;
    gap: 10px;
    margin-bottom: 18px;
  }

  .section-intro {
    text-align: left;
  }

  .sample-side,
  .question-block {
    padding: 15px;
  }

  .task-label {
    padding: 11px 15px;
  }

  .image-stage {
    grid-template-rows: minmax(280px, 1fr) auto;
  }

  .image-stage img {
    min-height: 280px;
    max-height: 380px;
    padding: 12px;
  }

  .answer-grid,
  .research-lower,
  .evidence-layout {
    grid-template-columns: 1fr;
  }

  .answer-panel + .answer-panel {
    border-top: 1px solid var(--line-strong);
    border-left: 0;
  }

  .flow-branch {
    grid-template-columns: 1fr;
  }

  .flow-vs {
    text-align: center;
  }

  .research-lower {
    gap: 24px;
  }

  .seed-row {
    grid-template-columns: 1fr 1fr;
  }

  .seed-coincide,
  .seed-delta {
    text-align: left;
  }

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

  .status-value {
    justify-self: start;
    text-align: left;
  }

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

  .evidence-layout {
    gap: 1px;
  }

  .technical-details dl {
    grid-template-columns: 1fr;
  }

  .technical-details dt {
    padding-bottom: 2px;
    border-bottom: 0;
  }

  .technical-details dd {
    padding-top: 2px;
  }

  .roadmap-item {
    grid-template-columns: 1fr;
  }

  .roadmap-state {
    justify-self: start;
    margin-left: 36px;
    text-align: left;
  }

  footer {
    grid-template-columns: 1fr;
    padding: 20px 18px 38px;
  }

  footer p:last-child {
    text-align: left;
  }

  .demo-controller {
    right: 10px;
    bottom: 10px;
    left: 10px;
    grid-template-columns: 1fr auto;
    gap: 10px;
  }

  .demo-progress-wrap {
    grid-column: 1 / -1;
    grid-row: 2;
  }
}

@media (max-width: 360px) {
  .challenge-title-tail {
    display: block;
  }

  .challenge-screen {
    padding-right: 10px;
    padding-left: 10px;
  }

  .challenge-note {
    grid-template-columns: 1fr;
  }

  .challenge-note span,
  .challenge-note small {
    grid-column: auto;
  }

  .round-progress li {
    font-size: 0.5rem;
  }

  .challenge-sheet {
    padding-right: 14px;
    padding-left: 14px;
  }

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

  .hero-facts li {
    font-size: 0.65rem;
  }
}

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

  .demo-active {
    transition: none;
  }

  .strategy-choices button,
  .reason-choices button,
  .sample-envelope {
    transition: none;
  }

  .strategy-choices button:hover,
  .reason-choices button:hover,
  .sample-envelope:hover,
  .sample-envelope.is-selected {
    transform: none;
  }
}