:root {
  color-scheme: light;
  --bg: #f5f7fb;
  --surface: #ffffff;
  --surface-soft: #eef3f8;
  --text: #16202a;
  --muted: #5e6b78;
  --line: #c8d2dc;
  --accent: #22577a;
  --accent-strong: #163d57;
  --focus: #8a4b08;
  --success: #1f6f43;
  --warning: #8a4b08;
  --danger: #8f2632;
  --radius: 16px;
  --shadow: 0 12px 36px rgba(22, 32, 42, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

a {
  color: var(--accent);
}

a:focus-visible,
button:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
}

button {
  font: inherit;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  padding: 0.75rem 1rem;
  background: var(--text);
  color: #fff;
  z-index: 10;
}

.skip-link:focus {
  top: 1rem;
}

.shell {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
}

.site-header {
  padding: 4.5rem 0 3.5rem;
  background: linear-gradient(140deg, #f8fbff 0%, #e7f0f7 100%);
  border-bottom: 1px solid var(--line);
}

.site-header h1 {
  max-width: 900px;
  margin: 0.3rem 0 1rem;
  font-size: clamp(2.25rem, 6vw, 4.7rem);
  line-height: 1.02;
  letter-spacing: -0.045em;
}

.lede {
  max-width: 800px;
  margin: 0;
  font-size: clamp(1.05rem, 2vw, 1.3rem);
  color: var(--muted);
}

.eyebrow {
  margin: 0;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--accent-strong);
}

.link-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
  align-items: center;
}

.link-row a,
.status-chip {
  display: inline-flex;
  align-items: center;
  min-height: 2.75rem;
  padding: 0.55rem 0.9rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  text-decoration: none;
  font-weight: 700;
}

main {
  padding: 2.5rem 0 4rem;
}

main > section + section {
  margin-top: 1.5rem;
}

.principles,
.controls,
.architecture,
.panel,
.notice {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.principles,
.controls,
.architecture,
.panel,
.notice {
  padding: clamp(1.2rem, 3vw, 2rem);
}

.principles h2,
.controls h2,
.architecture h2,
.panel h2 {
  margin: 0.3rem 0 0;
}

.principle-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}

.principle-card {
  display: grid;
  place-items: center;
  gap: 0.2rem;
  min-height: 130px;
  padding: 1rem;
  text-align: center;
  background: var(--surface-soft);
  border-radius: 12px;
  font-weight: 700;
}

.principle-card strong {
  font-size: 1.45rem;
  color: var(--accent-strong);
}

.controls {
  display: flex;
  gap: 1rem;
  align-items: center;
  justify-content: space-between;
}

.scenario-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

.scenario-buttons button,
.stage-controls button {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text);
  padding: 0.72rem 1rem;
  cursor: pointer;
  font-weight: 800;
}

.scenario-buttons button[aria-pressed="true"] {
  background: var(--accent-strong);
  color: #fff;
  border-color: var(--accent-strong);
}

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

.architecture-flow {
  margin-top: 1.25rem;
}

.flow-source {
  width: min(520px, 100%);
  margin: 0 auto;
  padding: 0.9rem;
  border-radius: 12px;
  background: var(--accent-strong);
  color: #fff;
  text-align: center;
  font-weight: 800;
}

.flow-branches {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
  position: relative;
}

.flow-branches::before {
  content: "";
  position: absolute;
  top: -1.5rem;
  left: 50%;
  width: 1px;
  height: 1.5rem;
  background: var(--line);
}

.flow-card {
  position: relative;
  display: grid;
  gap: 0.35rem;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface-soft);
  text-align: center;
}

.flow-card strong {
  color: var(--accent-strong);
}

.demo-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(280px, 0.8fr);
  gap: 1.5rem;
}

.panel-heading {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: flex-start;
}

.stage-count {
  padding: 0.4rem 0.7rem;
  border-radius: 999px;
  background: var(--surface-soft);
  font-weight: 800;
}

.metrics,
.compact-metrics {
  margin: 1.25rem 0 0;
}

.metrics > div,
.compact-metrics > div {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 1rem;
  padding: 0.8rem 0;
  border-top: 1px solid var(--line);
}

.metrics dt,
.compact-metrics dt {
  color: var(--muted);
}

.metrics dd,
.compact-metrics dd {
  margin: 0;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-weight: 800;
  text-align: right;
}

.value-success {
  color: var(--success);
}

.value-warning {
  color: var(--warning);
}

.value-danger {
  color: var(--danger);
}

.stage-controls {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.highlight-panel {
  background: linear-gradient(160deg, #163d57 0%, #22577a 100%);
  color: #fff;
}

.highlight-panel .eyebrow {
  color: #dcecf6;
}

.highlight-panel h2 {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  overflow-wrap: anywhere;
}

.guard-explanation {
  margin-top: 1.2rem;
  padding-top: 1rem;
  border-top: 1px solid rgba(255, 255, 255, 0.28);
  color: #e8f2f8;
}

.timeline {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 0.75rem;
  padding: 0;
  margin: 1.25rem 0 0;
  list-style: none;
}

.timeline li {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.9rem;
  background: var(--surface-soft);
}

.timeline li[aria-current="step"] {
  border: 3px solid var(--accent-strong);
  padding: calc(0.9rem - 2px);
  background: #e4eef5;
}

.timeline button {
  display: grid;
  width: 100%;
  gap: 0.35rem;
  border: 0;
  padding: 0;
  background: transparent;
  color: inherit;
  text-align: left;
  cursor: pointer;
}

.timeline .timeline-response {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-weight: 800;
}

.comparison-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.5rem;
  margin-top: 1rem;
}

.comparison-grid > div {
  padding: 1rem;
  background: var(--surface-soft);
  border-radius: 12px;
}

.comparison-grid h3 {
  margin-top: 0;
}

.notice {
  border-left: 6px solid var(--warning);
}

.notice p:last-child {
  margin-bottom: 0;
}

.site-footer {
  padding: 2rem 0;
  border-top: 1px solid var(--line);
  color: var(--muted);
}

@media (max-width: 820px) {
  .principle-grid,
  .demo-grid,
  .comparison-grid,
  .flow-branches {
    grid-template-columns: 1fr;
  }

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

  .flow-branches::before {
    display: none;
  }
}

@media (max-width: 560px) {
  .site-header {
    padding-top: 3rem;
  }

  .shell {
    width: min(100% - 1rem, 1120px);
  }

  .metrics > div,
  .compact-metrics > div {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }

  .metrics dd,
  .compact-metrics dd {
    text-align: left;
  }

  .stage-controls {
    flex-direction: column;
  }

  .stage-controls button {
    width: 100%;
  }
}