.proof-panel {
  background:
    radial-gradient(circle at 82% 25%, rgba(255, 255, 255, .36), transparent 22%),
    radial-gradient(circle at 70% 58%, rgba(116, 110, 255, .2), transparent 32%),
    var(--lime);
}

.proof-model {
  min-height: 500px;
  perspective: 1250px;
  cursor: grab;
  user-select: none;
  touch-action: pan-y;
  outline: none;
}

.proof-model.is-dragging { cursor: grabbing; }

.proof-model:focus-visible::after {
  content: "";
  position: absolute;
  inset: 4%;
  border: 3px solid var(--ink);
  border-radius: 18px;
  pointer-events: none;
}

.proof-model-stage {
  position: absolute;
  inset: 7% 0 15%;
  transform-style: preserve-3d;
  will-change: transform;
}

.proof-model .stack {
  appearance: none;
  position: absolute;
  left: 7%;
  top: 18%;
  width: 86%;
  height: 64%;
  padding: clamp(1rem, 2vw, 1.8rem);
  border: 1px solid var(--ink);
  border-radius: 18px;
  color: var(--ink);
  font: inherit;
  text-align: left;
  letter-spacing: normal;
  transform-style: preserve-3d;
  display: grid;
  grid-template-rows: auto auto 1fr auto;
  gap: clamp(.5rem, 1vw, .9rem);
  box-shadow: 0 28px 55px rgba(23, 24, 21, .2), 14px 18px 0 rgba(23, 24, 21, .1);
  backface-visibility: visible;
  will-change: transform;
  transition: filter .25s ease, box-shadow .25s ease;
  overflow: hidden;
}

.proof-model .stack::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(125deg, rgba(255, 255, 255, .26), transparent 34%, transparent 68%, rgba(23, 24, 21, .08));
  pointer-events: none;
}

.proof-model .stack:hover,
.proof-model .stack:focus-visible {
  filter: brightness(1.035) saturate(1.06);
  box-shadow: 0 34px 65px rgba(23, 24, 21, .26), 0 0 0 4px rgba(255, 255, 255, .72);
  outline: none;
}

.proof-model .stack-back { background: var(--coral); }
.proof-model .stack-mid { background: var(--blue); color: white; }
.proof-model .stack-front { background: var(--paper); }

.stack-top {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.stack-top b,
.stack-top i {
  font-size: clamp(.5rem, .72vw, .66rem);
  font-style: normal;
  font-weight: 900;
  letter-spacing: .12em;
  text-transform: uppercase;
}

.stack-top i { opacity: .64; text-align: right; }

.proof-model .stack > strong {
  position: relative;
  z-index: 1;
  max-width: 82%;
  font-family: var(--display);
  font-size: clamp(1.15rem, 2.25vw, 2.2rem);
  line-height: .98;
  letter-spacing: -.055em;
}

.proof-model .stack > p {
  position: relative;
  z-index: 1;
  max-width: 70%;
  margin: 0;
  align-self: start;
  font-size: clamp(.62rem, .88vw, .82rem);
  font-weight: 680;
  line-height: 1.35;
}

.connection-map {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: auto 1fr auto 1fr auto;
  align-items: center;
  gap: .45rem;
}

.connection-map em {
  border: 1px solid currentColor;
  border-radius: 999px;
  padding: .38rem .58rem;
  font-size: clamp(.42rem, .6vw, .56rem);
  font-style: normal;
  font-weight: 850;
  letter-spacing: .08em;
  text-transform: uppercase;
  white-space: nowrap;
}

.connection-map > i {
  position: relative;
  height: 1px;
  background: currentColor;
  opacity: .55;
}

.connection-map > i::after {
  content: "";
  position: absolute;
  right: -1px;
  top: -3px;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: currentColor;
}

.connection-map .is-current { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.stack-mid .connection-map .is-current { background: var(--paper); color: var(--ink); border-color: var(--paper); }

.proof-model-help {
  position: absolute;
  left: 4%;
  right: 4%;
  bottom: 1%;
  margin: 0;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  font-size: .56rem;
  font-weight: 850;
  letter-spacing: .12em;
  text-transform: uppercase;
}

.deck-controls {
  position: absolute;
  left: 50%;
  bottom: 7%;
  z-index: 400;
  transform: translateX(-50%);
  display: flex;
  gap: .25rem;
  padding: .28rem;
  border: 1px solid rgba(23, 24, 21, .4);
  border-radius: 999px;
  background: rgba(242, 239, 230, .88);
  box-shadow: 0 10px 24px rgba(23, 24, 21, .14);
  backdrop-filter: blur(10px);
}

.deck-controls button {
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: var(--ink);
  padding: .48rem .72rem;
  font-size: .52rem;
  font-weight: 850;
  letter-spacing: .08em;
  text-transform: uppercase;
  cursor: pointer;
}

.deck-controls button:hover,
.deck-controls button:focus-visible { background: rgba(23, 24, 21, .1); outline: none; }
.deck-controls button.is-active { background: var(--ink); color: var(--paper); }

.proof-model-help span:first-child::before { content: "↕"; margin-right: .5rem; }
.proof-model-help span:last-child::after { content: " ●"; color: var(--coral); }

@media (max-width: 900px) {
  .proof-model { min-height: 470px; }
  .proof-model-stage { inset: 7% 2% 15%; }
}

@media (max-width: 560px) {
  .proof-model { min-height: 410px; touch-action: pan-y; overflow: hidden; }
  .proof-model-stage { inset: 4% 0 18%; }
  .proof-model .stack { left: 10%; top: 14%; width: 80%; height: 69%; padding: 1rem; border-radius: 18px; box-shadow: 0 18px 38px rgba(23,24,21,.18), 8px 10px 0 rgba(23,24,21,.07); transform-origin: center center; transition: transform .52s cubic-bezier(.2,.82,.22,1), opacity .34s ease, filter .25s ease, box-shadow .25s ease; }
  .proof-model.is-dragging .stack { transition-duration: .08s; }
  .proof-model .stack[aria-pressed="false"] { filter: saturate(.88) brightness(.96); }
  .proof-model .stack[aria-pressed="true"] { filter: none; box-shadow: 0 28px 52px rgba(23,24,21,.25), 0 0 0 3px rgba(255,255,255,.72); }
  .proof-model .stack > strong { max-width: 94%; font-size: 1.1rem; }
  .proof-model .stack > p { max-width: 92%; font-size: .62rem; line-height: 1.42; }
  .stack-top i { display: none; }
  .connection-map { gap: .25rem; }
  .connection-map em { padding: .34rem .42rem; font-size: .4rem; }
  .proof-model-help { left: 0; right: 0; justify-content: center; }
  .proof-model-help span:first-child { font-size: 0; }
  .proof-model-help span:first-child::before { content: "↔  Swipe to rotate the deck"; font-size: .54rem; }
  .proof-model-help span:last-child { display: none; }
  .deck-controls { bottom: 7%; width: min(94%, 330px); justify-content: stretch; }
  .deck-controls button { flex: 1; min-height: 38px; padding: .45rem .55rem; font-size: .47rem; }
}

@media (prefers-reduced-motion: reduce) {
  .proof-model-stage,
  .proof-model .stack { will-change: auto; }
}