:root {
  --bg: 9 11 15;
  --surface: 17 19 25;
  --ink: 237 238 242;
  --muted: 140 143 155;
  --border: 255 255 255;
  --accent: 129 111 246;
  --success: 52 211 153;
  --error: 248 113 113;

  --ease-out-quad: cubic-bezier(0.25, 0.46, 0.45, 0.94);
  --ease-flip: cubic-bezier(0.65, 0, 0.35, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  min-height: 100vh;
  background: rgb(var(--bg));
  color: rgb(var(--ink));
  font-family: 'Space Grotesk', system-ui, sans-serif;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem 1.25rem;
}

.mono {
  font-family: 'Space Mono', ui-monospace, monospace;
}

.stage {
  width: 100%;
  max-width: 380px;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* ---------- 3D card ---------- */
.card-scene {
  width: 100%;
  aspect-ratio: 1.586;
  perspective: 1200px;
}

.card-3d {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 650ms var(--ease-flip);
}

.card-3d.is-flipped {
  transform: rotateY(180deg);
}

@media (prefers-reduced-motion: reduce) {
  .card-3d {
    transition-duration: 1ms;
  }
}

.card-face {
  position: absolute;
  inset: 0;
  border-radius: 18px;
  backface-visibility: hidden;
  padding: 1.4rem 1.5rem;
  box-shadow: 0 25px 50px -20px rgb(0 0 0 / 0.6);
  color: white;
}

.card-face--front {
  background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 45%, #d946a8 100%);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.card-face__top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
}

.chip {
  width: 38px;
  height: 28px;
  border-radius: 6px;
  background: linear-gradient(160deg, #f4e397, #c9a227);
  position: relative;
  overflow: hidden;
}

.chip::before,
.chip::after {
  content: '';
  position: absolute;
  background: rgb(0 0 0 / 0.25);
}

.chip::before {
  left: 50%;
  top: 0;
  bottom: 0;
  width: 1.5px;
}

.chip::after {
  top: 50%;
  left: 0;
  right: 0;
  height: 1.5px;
}

.network {
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  font-style: italic;
  opacity: 0.9;
}

.card-number {
  font-size: clamp(1.15rem, 5.5vw, 1.4rem);
  font-weight: 700;
  letter-spacing: 0.12em;
}

.card-face__bottom {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  min-width: 0;
}

.field--right {
  text-align: right;
  align-items: flex-end;
}

.field-label {
  font-size: 0.6rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  opacity: 0.65;
}

.field-value {
  font-size: 0.85rem;
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  text-transform: uppercase;
}

.card-face--back {
  background: rgb(24 26 33);
  transform: rotateY(180deg);
  padding: 0;
  display: flex;
  flex-direction: column;
}

.magstripe {
  background: rgb(10 10 12);
  height: 22%;
  margin-top: 1.5rem;
}

.cvv-strip {
  margin: 1.25rem 1.5rem 0;
  background: rgb(255 255 255 / 0.92);
  border-radius: 6px;
  padding: 0.6rem 0.9rem;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 0.6rem;
}

.cvv-strip__label {
  color: rgb(90 90 95);
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
}

.cvv-strip__value {
  color: rgb(30 30 33);
  font-size: 0.9rem;
  letter-spacing: 0.15em;
}

/* ---------- Form panel ---------- */
.panel {
  background: rgb(var(--surface));
  border: 1px solid rgb(var(--border) / 0.08);
  border-radius: 18px;
  padding: 1.75rem;
}

.panel[hidden] {
  display: none;
}

h1 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 1.25rem;
}

.field-group {
  margin-bottom: 1rem;
}

label {
  display: block;
  font-size: 0.78rem;
  font-weight: 600;
  color: rgb(var(--muted));
  margin-bottom: 0.4rem;
}

input {
  width: 100%;
  padding: 0.75rem 0.9rem;
  font-family: 'Space Mono', ui-monospace, monospace;
  font-size: 0.92rem;
  color: rgb(var(--ink));
  background: rgb(var(--bg));
  border: 1.5px solid rgb(var(--border) / 0.12);
  border-radius: 10px;
  outline: none;
  transition: border-color 200ms ease;
}

input:focus {
  border-color: rgb(var(--accent));
}

input.is-invalid {
  border-color: rgb(var(--error));
}

.row {
  display: flex;
  gap: 0.85rem;
}

.row .field-group {
  flex: 1;
}

.submit-btn {
  width: 100%;
  padding: 0.85rem;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 700;
  color: white;
  background: rgb(var(--accent));
  border: none;
  border-radius: 10px;
  cursor: pointer;
  margin-top: 0.4rem;
  transition:
    transform 150ms var(--ease-out-quad),
    background-color 200ms ease;
}

@media (hover: hover) and (pointer: fine) {
  .submit-btn:hover {
    background: rgb(112 94 232);
  }
}

.submit-btn:active {
  transform: scale(0.98);
}

/* ---------- Success ---------- */
.panel--success {
  text-align: center;
  animation: rise 400ms var(--ease-out-quad);
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (prefers-reduced-motion: reduce) {
  .panel--success {
    animation: none;
  }
}

.success-icon {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: rgb(var(--success) / 0.15);
  color: rgb(var(--success));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  font-weight: 700;
  margin: 0 auto 1rem;
}

.panel--success p {
  color: rgb(var(--muted));
  font-size: 0.9rem;
  margin-bottom: 1.5rem;
}

.btn-ghost {
  width: 100%;
  padding: 0.8rem;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  color: rgb(var(--ink));
  background: rgb(var(--border) / 0.08);
  border: none;
  border-radius: 10px;
  cursor: pointer;
}

@media (hover: hover) and (pointer: fine) {
  .btn-ghost:hover {
    background: rgb(var(--border) / 0.14);
  }
}