:root {
  color-scheme: light dark;
  --font-ui: Aptos, "Segoe UI", ui-sans-serif, system-ui, -apple-system, sans-serif;
  --font-mono: "SFMono-Regular", "Cascadia Code", Consolas, ui-monospace, monospace;
  --color-accent: #1553d7;
  --color-accent-strong: #0d3fa8;
  --color-accent-soft: #e7efff;
  --color-canvas: #f4f7fb;
  --color-surface: #fbfcfe;
  --color-surface-raised: #eef3fa;
  --color-ink: #202938;
  --color-ink-strong: #111827;
  --color-muted: #566174;
  --color-subtle: #6b7688;
  --color-line: #cbd4e1;
  --radius-control: 8px;
  --radius-panel: 8px;
  --shadow-panel: 0 22px 60px rgb(25 45 82 / 14%);
  --page-width: 1200px;
  --header-height: 68px;
  --z-header: 20;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-accent: #79a4ff;
    --color-accent-strong: #9bb9ff;
    --color-accent-soft: #172b52;
    --color-canvas: #111722;
    --color-surface: #151e2c;
    --color-surface-raised: #1c2737;
    --color-ink: #dbe4f1;
    --color-ink-strong: #f1f5fb;
    --color-muted: #b3bfd0;
    --color-subtle: #9aa8ba;
    --color-line: #344155;
    --shadow-panel: 0 22px 60px rgb(0 0 0 / 30%);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 24px);
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--color-canvas);
  color: var(--color-ink);
  font-family: var(--font-ui);
  font-size: 17px;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

body::before {
  position: fixed;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(rgb(21 83 215 / 3%) 1px, transparent 1px),
    linear-gradient(90deg, rgb(21 83 215 / 3%) 1px, transparent 1px);
  background-size: 48px 48px;
  content: "";
  pointer-events: none;
}

img {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 4px;
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 12px;
  z-index: 100;
  padding: 10px 14px;
  border-radius: var(--radius-control);
  background: var(--color-ink-strong);
  color: var(--color-surface);
  font-weight: 750;
  transform: translateY(-150%);
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  min-height: var(--header-height);
  border-bottom: 1px solid color-mix(in srgb, var(--color-line) 76%, transparent);
  background: color-mix(in srgb, var(--color-canvas) 90%, transparent);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

.site-nav {
  width: min(calc(100% - 40px), var(--page-width));
  min-height: var(--header-height);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 13px;
  color: var(--color-ink-strong);
  font-weight: 780;
  text-decoration: none;
  white-space: nowrap;
}

.brand-name {
  font-size: 20px;
  letter-spacing: -0.02em;
}

.brand-divider {
  width: 1px;
  height: 24px;
  background: var(--color-line);
}

.brand-topic {
  color: var(--color-muted);
  font-size: 14px;
  font-weight: 700;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 30px;
}

.nav-links a {
  color: var(--color-muted);
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}

.nav-links a:hover {
  color: var(--color-accent);
}

.menu-button {
  display: none;
  min-height: 40px;
  padding: 8px 12px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-control);
  background: var(--color-surface);
  color: var(--color-ink-strong);
  font: inherit;
  font-size: 14px;
  font-weight: 750;
}

main {
  overflow: clip;
}

.hero {
  width: min(calc(100% - 40px), 1320px);
  min-height: calc(100dvh - var(--header-height));
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(500px, 1fr);
  align-items: center;
  gap: clamp(40px, 5vw, 72px);
  padding: 68px 0;
}

.hero-copy {
  position: relative;
  z-index: 1;
  max-width: 600px;
}

.eyebrow {
  margin: 0 0 20px;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  text-wrap: pretty;
}

h1,
h2,
h3 {
  margin-top: 0;
  color: var(--color-ink-strong);
  line-height: 1.08;
}

h1 {
  max-width: 12ch;
  margin-bottom: 24px;
  font-size: clamp(40px, 5vw, 72px);
  font-weight: 770;
  letter-spacing: -0.055em;
}

.title-line {
  display: block;
  white-space: nowrap;
}

.hero-summary {
  max-width: 48ch;
  margin: 0 0 34px;
  color: var(--color-muted);
  font-size: clamp(18px, 2vw, 22px);
  line-height: 1.5;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.button {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 18px;
  border: 1px solid transparent;
  border-radius: var(--radius-control);
  font-size: 15px;
  font-weight: 780;
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
  transition:
    transform 160ms ease,
    background-color 160ms ease,
    border-color 160ms ease;
}

.button:hover {
  transform: translateY(-2px);
}

.button:active {
  transform: translateY(1px);
}

.button-primary {
  border-color: var(--color-accent-strong);
  background: var(--color-accent-strong);
  color: #f8fbff;
}

.button-primary:hover {
  border-color: var(--color-accent);
  background: var(--color-accent);
}

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

.button-secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.hero-visual {
  position: relative;
  margin: 0;
}

.hero-visual::before {
  position: absolute;
  inset: 28px -24px -28px 34px;
  z-index: -1;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-panel);
  background: var(--color-accent-soft);
  content: "";
}

.hero-visual img {
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  border-radius: var(--radius-panel);
  box-shadow: var(--shadow-panel);
  object-fit: cover;
}

.section-pad {
  width: min(calc(100% - 40px), var(--page-width));
  margin: 0 auto;
  padding: clamp(88px, 11vw, 150px) 0;
}

.statement {
  display: grid;
  grid-template-columns: minmax(140px, 0.32fr) minmax(0, 1fr);
  gap: clamp(30px, 7vw, 100px);
  align-items: start;
}

.statement-rule {
  height: 6px;
  margin-top: 18px;
  background: var(--color-accent);
}

.statement h2 {
  max-width: 17ch;
  margin-bottom: 28px;
  font-size: clamp(38px, 5vw, 68px);
  letter-spacing: -0.045em;
}

.statement p {
  max-width: 58ch;
  margin: 0;
  color: var(--color-muted);
  font-size: clamp(20px, 2.2vw, 27px);
}

.section-heading {
  max-width: 760px;
  margin-bottom: clamp(48px, 7vw, 84px);
}

.section-heading h2,
.knowledge-copy h2,
.guardrail-intro h2 {
  margin-bottom: 22px;
  font-size: clamp(38px, 4.8vw, 66px);
  letter-spacing: -0.045em;
}

.section-heading p,
.knowledge-copy > p,
.guardrail-intro > p {
  max-width: 62ch;
  margin: 0;
  color: var(--color-muted);
  font-size: 19px;
}

.model-path {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none;
}

.model-path::before {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 96px;
  width: 1px;
  background: var(--color-line);
  content: "";
}

.model-step {
  position: relative;
  display: grid;
  grid-template-columns: 192px minmax(0, 1fr);
  gap: 36px;
  padding: 0 0 58px;
}

.model-step:last-child {
  padding-bottom: 0;
}

.step-marker {
  position: relative;
  z-index: 1;
  width: 112px;
  min-height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  justify-self: center;
  border: 1px solid var(--color-accent);
  border-radius: var(--radius-control);
  background: var(--color-canvas);
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.model-step h3 {
  margin-bottom: 12px;
  font-size: clamp(24px, 3vw, 34px);
  letter-spacing: -0.025em;
}

.model-step p {
  max-width: 58ch;
  margin: 0;
  color: var(--color-muted);
}

.capability-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  grid-template-areas:
    "build memory"
    "build context"
    "repeat check";
  gap: 18px;
}

.capability {
  min-height: 230px;
  padding: clamp(26px, 4vw, 48px);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-panel);
  background: var(--color-surface);
}

.capability-build {
  grid-area: build;
  min-height: 478px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  background:
    linear-gradient(180deg, transparent 46%, color-mix(in srgb, var(--color-canvas) 94%, transparent)),
    url("./assets/durable-knowledge.webp") center 30% / cover;
}

.capability-build p,
.capability-build h3 {
  max-width: 520px;
  padding-right: 8px;
}

.capability-memory {
  grid-area: memory;
  background: var(--color-accent-soft);
}

.capability-context {
  grid-area: context;
}

.capability-repeat {
  grid-area: repeat;
}

.capability-check {
  grid-area: check;
  background: var(--color-surface-raised);
}

.capability-label {
  margin: 0 0 30px;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.capability h3 {
  margin-bottom: 16px;
  font-size: clamp(25px, 3vw, 36px);
  letter-spacing: -0.03em;
}

.capability p:last-child {
  margin: 0;
  color: var(--color-muted);
}

.capability-build .capability-label,
.capability-build h3,
.capability-build p:last-child {
  width: fit-content;
  padding: 8px 11px;
  background: color-mix(in srgb, var(--color-canvas) 94%, transparent);
}

.knowledge {
  display: grid;
  grid-template-columns: minmax(360px, 0.8fr) minmax(0, 1.2fr);
  gap: clamp(48px, 8vw, 112px);
  align-items: center;
}

.knowledge-image {
  margin: 0;
}

.knowledge-image img {
  width: 100%;
  aspect-ratio: 4 / 5;
  border-radius: var(--radius-panel);
  box-shadow: var(--shadow-panel);
  object-fit: cover;
}

.knowledge-copy blockquote {
  max-width: 29ch;
  margin: 44px 0 0;
  padding: 28px 0 0;
  border-top: 3px solid var(--color-accent);
  color: var(--color-ink-strong);
  font-size: clamp(24px, 3.1vw, 38px);
  font-weight: 690;
  line-height: 1.3;
  letter-spacing: -0.025em;
}

.guardrails {
  display: grid;
  grid-template-columns: minmax(0, 0.82fr) minmax(0, 1.18fr);
  gap: clamp(52px, 9vw, 124px);
}

.guardrail-intro {
  position: sticky;
  top: calc(var(--header-height) + 54px);
  align-self: start;
}

.guardrail-lines {
  border-top: 1px solid var(--color-line);
}

.guardrail-line {
  padding: 38px 0;
  border-bottom: 1px solid var(--color-line);
}

.guardrail-line h3 {
  margin-bottom: 12px;
  font-size: 26px;
  letter-spacing: -0.02em;
}

.guardrail-line p {
  max-width: 54ch;
  margin: 0;
  color: var(--color-muted);
}

.pilot-flow {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 18px;
}

.pilot-item {
  min-height: 240px;
  padding: clamp(28px, 4vw, 46px);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-panel);
  background: var(--color-surface);
}

.pilot-item:nth-child(2),
.pilot-item:nth-child(3) {
  background: var(--color-surface-raised);
}

.pilot-item span {
  display: inline-block;
  margin-bottom: 42px;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.pilot-item h3 {
  margin-bottom: 14px;
  font-size: clamp(25px, 3vw, 34px);
  letter-spacing: -0.025em;
}

.pilot-item p {
  margin: 0;
  color: var(--color-muted);
}

.question-list {
  max-width: 900px;
}

.question-list details {
  border-bottom: 1px solid var(--color-line);
}

.question-list details:first-child {
  border-top: 1px solid var(--color-line);
}

.question-list summary {
  position: relative;
  padding: 28px 58px 28px 0;
  color: var(--color-ink-strong);
  font-size: clamp(20px, 2.6vw, 28px);
  font-weight: 720;
  line-height: 1.3;
  cursor: pointer;
  list-style: none;
}

.question-list summary::-webkit-details-marker {
  display: none;
}

.question-list summary::after {
  position: absolute;
  top: 50%;
  right: 8px;
  color: var(--color-accent);
  content: "+";
  font-family: var(--font-mono);
  font-size: 30px;
  font-weight: 500;
  transform: translateY(-50%);
}

.question-list details[open] summary::after {
  content: "-";
}

.question-list details p {
  max-width: 68ch;
  margin: 0;
  padding: 0 56px 30px 0;
  color: var(--color-muted);
}

.closing {
  display: grid;
  justify-items: start;
  border-top: 1px solid var(--color-line);
}

.closing-kicker {
  margin: 0 0 24px;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.closing h2 {
  max-width: 20ch;
  margin-bottom: 42px;
  font-size: clamp(40px, 6vw, 78px);
  letter-spacing: -0.05em;
}

.site-footer {
  width: min(calc(100% - 40px), var(--page-width));
  margin: 0 auto;
  display: grid;
  grid-template-columns: 0.45fr 1fr;
  gap: 30px;
  padding: 30px 0 42px;
  border-top: 1px solid var(--color-line);
  color: var(--color-muted);
  font-size: 13px;
}

.site-footer p {
  margin: 0;
}

.site-footer p:first-child {
  color: var(--color-ink-strong);
  font-weight: 780;
}

.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition:
    opacity 600ms cubic-bezier(0.16, 1, 0.3, 1),
    transform 600ms cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 980px) {
  .hero {
    min-height: auto;
    grid-template-columns: 1fr;
    padding: 72px 0 98px;
  }

  .hero-copy {
    max-width: 760px;
  }

  h1 {
    max-width: 12ch;
  }

  .hero-visual {
    width: min(100%, 780px);
    justify-self: end;
  }

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

  .guardrail-intro {
    position: static;
  }
}

@media (max-width: 760px) {
  :root {
    --header-height: 62px;
  }

  body {
    font-size: 16px;
  }

  .site-nav {
    position: relative;
    width: min(calc(100% - 28px), var(--page-width));
  }

  .menu-button {
    display: inline-flex;
    align-items: center;
  }

  .nav-links {
    position: absolute;
    top: calc(100% + 1px);
    right: 0;
    left: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px;
    border: 1px solid var(--color-line);
    border-radius: 0 0 var(--radius-panel) var(--radius-panel);
    background: var(--color-surface);
    box-shadow: var(--shadow-panel);
  }

  .nav-links.is-open {
    display: flex;
  }

  .nav-links a {
    min-height: 44px;
    display: flex;
    align-items: center;
    padding: 0 12px;
  }

  .hero,
  .section-pad,
  .site-footer {
    width: min(calc(100% - 28px), var(--page-width));
  }

  .hero {
    gap: 54px;
    padding: 56px 0 82px;
  }

  h1 {
    max-width: none;
    font-size: clamp(38px, 10vw, 48px);
  }

  .hero-visual::before {
    inset: 16px -10px -18px 18px;
  }

  .statement {
    grid-template-columns: 1fr;
    gap: 30px;
  }

  .statement-rule {
    width: 96px;
    margin-top: 0;
  }

  .model-path::before {
    left: 55px;
  }

  .model-step {
    grid-template-columns: 110px minmax(0, 1fr);
    gap: 18px;
    padding-bottom: 44px;
  }

  .step-marker {
    width: 90px;
    justify-self: start;
    font-size: 10px;
  }

  .capability-grid {
    grid-template-columns: 1fr;
    grid-template-areas:
      "build"
      "memory"
      "context"
      "repeat"
      "check";
  }

  .capability-build {
    min-height: 440px;
  }

  .knowledge {
    grid-template-columns: 1fr;
    gap: 54px;
  }

  .knowledge-image {
    width: min(88%, 520px);
  }

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

  .site-footer {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .brand-topic {
    display: none;
  }

  .brand-divider {
    display: none;
  }

  .hero-actions {
    flex-direction: column;
  }

  .button {
    width: 100%;
  }

  .model-path::before {
    display: none;
  }

  .model-step {
    grid-template-columns: 1fr;
  }

  .step-marker {
    justify-self: start;
  }

  .capability,
  .pilot-item {
    padding: 26px 22px;
  }

  .knowledge-image {
    width: 100%;
  }
}

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

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

  .reveal {
    opacity: 1;
    transform: none;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .site-header {
    background: var(--color-canvas);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }
}