.walkthrough .hero { min-height: 0; }
.walkthrough .hero-content { padding-bottom: 72px; }
.walkthrough .walkthrough-boundary { max-width: 720px; font-size: 15px; color: #b5bfb7; }
.proof-story { padding-top: 64px; padding-bottom: 24px; }
.walkthrough-summary { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; margin: 0 0 30px; padding: 24px; background: var(--accent-wash); }
.walkthrough-summary dt { color: var(--accent); font-size: 18px; font-weight: 700; }
.walkthrough-summary dd { margin: 10px 0 0; line-height: 1.6; }
.proof-steps { list-style: none; margin: 0; padding: 0; }
.proof-steps li { display: grid; grid-template-columns: 72px minmax(0, 1fr); gap: 24px; padding: 36px 0; border-bottom: 1px solid var(--line); }
.step-number { color: var(--accent); font-size: 24px; font-weight: 750; }
.proof-steps h2 { margin: 0 0 14px; font-size: clamp(24px, 3vw, 34px); letter-spacing: -0.035em; }
.proof-steps p { max-width: 850px; margin: 0 0 16px; }
.step-evidence { color: var(--muted); }
.quality-failure { color: #b92530; font-weight: 750; }
.model-identities { max-width: 850px; font-size: 14px; }
.model-identities dt { margin-top: 16px; font-weight: 700; }
.model-identities dd { margin: 4px 0; overflow-wrap: anywhere; font-family: ui-monospace, monospace; }
.proof-steps summary { cursor: pointer; color: var(--accent); }
@media (max-width: 600px) {
  .walkthrough-summary { grid-template-columns: 1fr; }
  .proof-steps li { grid-template-columns: 1fr; gap: 10px; }
  .walkthrough .site-header nav { display: none; }
}

.walkthrough .hero-copy { max-width: 900px; }
.walkthrough .hero-content { padding-top: 160px; }
.walkthrough .hero-copy > .eyebrow { color: var(--copper); margin: 0 0 28px; font-size: 13px; }
.walkthrough .hero-copy h1 span { color: var(--copper); }
@media (max-width: 860px) { .walkthrough .hero-content { padding-top: 116px; } }