/* =========================================================
   Integration Layers — vertical flip cards (sandbox)
   Capture → Route → Report
   Back first; scroll reveals front via rotateX only
   ========================================================= */

.proof-grid--flip {
  perspective: 1400px;
  align-items: stretch;
}

.proof-flip {
  position: relative;
  min-height: 240px;
  /* Preserve layout height while faces are absolute */
  height: 100%;
}

.proof-flip-inner {
  position: relative;
  width: 100%;
  min-height: 240px;
  height: 100%;
  transform-style: preserve-3d;
  /* Scroll-scrubbed via JS (no snap transition) — slow, continuous turn */
  transition: none;
  /* Start showing the BACK face */
  transform: rotateX(0deg);
  will-change: transform;
}

/* Class still toggled at end of scrub for styling hooks */
.proof-flip.is-flipped .proof-flip-inner {
  /* transform set inline by scroll script */
}

.proof-flip-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  padding: 1.35rem;
  border: 1px solid var(--border-dark);
  background: var(--surface-dark-card, rgba(255, 255, 255, 0.04));
  border-radius: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  box-sizing: border-box;
}

/* BACK: number top-left, word centered */
.proof-flip-face--back {
  transform: rotateX(0deg);
  justify-content: center;
  align-items: stretch;
}

.proof-flip-face--back .proof-flip-num {
  position: absolute;
  top: 1.35rem;
  left: 1.35rem;
  margin: 0;
}

.proof-flip-word {
  margin: 0;
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.65rem, 2.8vw, 2.15rem);
  line-height: 1.05;
  letter-spacing: 0;
  color: var(--text-light, #e8e6e1);
  text-align: center;
  padding: 2rem 0.5rem 0.5rem;
}

/* FRONT: full content (matches original proof-card) */
.proof-flip-face--front {
  transform: rotateX(180deg);
  justify-content: flex-start;
}

.proof-flip-num {
  display: block;
  font-family: var(--font-mono);
  color: var(--accent, #e85d30);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.9rem;
}

.proof-flip-face--front h3 {
  font-family: var(--font-display);
  font-size: 1.35rem;
  line-height: 1.12;
  letter-spacing: 0;
  margin: 0 0 0.8rem;
  color: var(--text-light, #e8e6e1);
}

.proof-flip-face--front p {
  margin: 0;
  color: var(--text-muted, #8891a0);
  line-height: 1.65;
  font-size: 0.98rem;
}

/* Soft edge while mid-flip */
.proof-flip.is-flipping .proof-flip-face {
  box-shadow: 0 18px 40px rgba(0, 0, 0, 0.22);
}

/* Reduced motion: show front content immediately, no 3D */
@media (prefers-reduced-motion: reduce) {
  .proof-flip-inner {
    transition: none !important;
    transform: rotateX(180deg) !important;
  }

  .proof-flip-face--back {
    display: none;
  }

  .proof-flip-face--front {
    position: relative;
    transform: none;
    backface-visibility: visible;
  }
}

@media (max-width: 900px) {
  .proof-grid--flip {
    perspective: 1000px;
  }

  .proof-flip,
  .proof-flip-inner {
    min-height: 210px;
  }

  .proof-flip-word {
    font-size: 1.55rem;
  }
}