/* Proof timeline: one real finding told in four steps, from report to fix,
   inside one surface panel. Each step opens with a 4px top rule: neutral for
   the finding and its cost, accent for the recommendation and its
   verification; never the warm colour, kept for regressions. One column on
   phones, two from the phone breakpoint, four from the tablet breakpoint. */

.proof-timeline {
  display: grid;
  gap: var(--space-m);
  margin: 0;
  padding: var(--space-m);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  background-color: var(--bg-surface);
  list-style: none;
}

@media (min-width: 640px) {
  .proof-timeline {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 880px) {
  .proof-timeline {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.proof-timeline__step {
  display: flex;
  flex-direction: column;
  gap: var(--space-2xs);
  padding-block-start: var(--space-s);
  border-block-start: 4px solid var(--border-strong);
}

.proof-timeline__step--recommended {
  border-block-start-color: var(--accent-soft);
}

.proof-timeline__step--verified {
  border-block-start-color: var(--accent);
}

.proof-timeline__label {
  color: var(--text-muted);
  font-size: var(--step--1);
  font-weight: 600;
  letter-spacing: var(--tracking-eyebrow);
  text-transform: uppercase;
}

.proof-timeline__step--recommended .proof-timeline__label,
.proof-timeline__step--verified .proof-timeline__label {
  color: var(--accent);
}

.proof-timeline__title {
  font-weight: 600;
  line-height: var(--leading-heading);
}

.proof-timeline__step > p:last-child {
  color: var(--text-secondary);
}