.balfour-feature {
  background: #ececf8;
  border-radius: 1.5rem;
  margin: clamp(2.5rem, 6vw, 5rem) 0;
  overflow: hidden;
  padding: clamp(2rem, 5vw, 4rem) clamp(1rem, 4vw, 3rem);
}

.balfour-feature__heading {
  margin: 0 auto;
  max-width: 48rem;
  text-align: center;
}

.balfour-feature__heading .eyebrow {
  color: #000;
}

.balfour-feature__heading h2 {
  color: #11131d;
  margin: 0.5rem 0 0.75rem;
}

.balfour-feature__heading > p:last-child {
  color: #313442;
  margin: 0;
}

.balfour-envelope-stage {
  --envelope-width: min(22.5rem, 82vw);
  align-items: center;
  display: flex;
  flex-direction: column;
  min-height: 25rem;
  padding-top: 4.75rem;
  position: relative;
  transition:
    min-height 0.8s cubic-bezier(0.22, 1, 0.36, 1),
    padding-top 0.8s cubic-bezier(0.22, 1, 0.36, 1);
}

.balfour-envelope-stage.is-open,
.balfour-envelope-stage.has-opened {
  min-height: 72rem;
  padding-top: 33rem;
}

.balfour-envelope {
  appearance: none;
  background: transparent;
  border: 0;
  color: inherit;
  cursor: pointer;
  display: block;
  flex: 0 0 auto;
  height: calc(var(--envelope-width) * 0.68);
  margin: 0;
  padding: 0;
  perspective: 75rem;
  position: relative;
  width: var(--envelope-width);
}

.balfour-envelope:focus-visible {
  outline: 0.2rem solid #0038b8;
  outline-offset: 0.65rem;
}

.balfour-envelope__back,
.balfour-envelope__pocket,
.balfour-envelope__flap {
  border-radius: 0.45rem;
  inset: 0;
  position: absolute;
}

.balfour-envelope__back {
  background:
    linear-gradient(145deg, rgba(255, 255, 255, 0.11), transparent 48%),
    #24262d;
  box-shadow: 0 1.2rem 2.6rem rgba(0, 0, 0, 0.3);
  z-index: 1;
}

.balfour-envelope__pocket {
  background:
    linear-gradient(32deg, #363941 49.5%, transparent 50%) left bottom / 51% 100% no-repeat,
    linear-gradient(-32deg, #2f323a 49.5%, transparent 50%) right bottom / 51% 100% no-repeat,
    linear-gradient(to top, #3d4048 0 48%, transparent 48%);
  box-shadow: inset 0 -0.1rem 0 rgba(255, 255, 255, 0.08);
  pointer-events: none;
  z-index: 4;
}

.balfour-envelope__flap {
  background: #454851;
  clip-path: polygon(0 0, 100% 0, 50% 57%);
  pointer-events: none;
  transform-origin: 50% 0;
  transform-style: preserve-3d;
  transition:
    transform 0.65s cubic-bezier(0.65, 0, 0.35, 1),
    z-index 0s linear 0.32s;
  z-index: 5;
}

.balfour-envelope-stage.is-open .balfour-envelope__flap {
  transform: rotateX(180deg);
  z-index: 2;
}

.balfour-letter {
  background: #f4ead4;
  border-radius: 0.25rem;
  box-shadow: 0 0.2rem 0.8rem rgba(0, 0, 0, 0.22);
  display: block;
  height: calc(var(--envelope-width) * 0.62);
  left: 1rem;
  overflow: hidden;
  position: absolute;
  top: 0.65rem;
  transform: translateY(0) scale(1);
  transform-origin: 50% 100%;
  transition:
    height 0.2s linear 0.45s,
    transform 0.85s cubic-bezier(0.22, 1, 0.36, 1),
    box-shadow 0.4s ease;
  width: calc(var(--envelope-width) - 2rem);
  z-index: 3;
}

.balfour-envelope-stage.is-open .balfour-letter {
  transform: translateY(calc(var(--envelope-width) * -0.32));
  z-index: 3;
}

.balfour-envelope-stage.is-unfolded .balfour-letter {
  box-shadow: 0 1.4rem 3.25rem rgba(13, 17, 29, 0.3);
  height: calc((var(--envelope-width) - 2rem) * 1.3635);
  overflow: visible;
  transform: translateY(calc(var(--envelope-width) * -0.34)) scale(1.875);
  z-index: 6;
}

.balfour-letter__image {
  display: block;
  height: auto;
  width: 100%;
}

.balfour-envelope__seal {
  align-items: center;
  background: #ffd64f;
  border: 0.18rem double rgba(17, 19, 29, 0.55);
  border-radius: 50%;
  box-shadow: 0 0.25rem 0.55rem rgba(0, 0, 0, 0.28);
  color: #11131d;
  display: flex;
  font-size: 0.8rem;
  font-weight: 800;
  height: 2.7rem;
  justify-content: center;
  left: 50%;
  letter-spacing: 0.08em;
  pointer-events: none;
  position: absolute;
  top: 48%;
  transform: translate(-50%, -50%);
  transition: opacity 0.2s ease;
  width: 2.7rem;
  z-index: 7;
}

.balfour-envelope-stage.is-open .balfour-envelope__seal {
  opacity: 0;
}

.balfour-envelope__hint {
  color: #11131d;
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  margin: 1.35rem 0 0;
  text-transform: uppercase;
}

.balfour-envelope__reset {
  background: #ffd64f;
  border: 0;
  border-radius: 999px;
  color: #000;
  cursor: pointer;
  font: inherit;
  font-weight: 800;
  margin-top: 1rem;
  padding: 0.8rem 1.35rem;
}

.balfour-envelope__reset:hover,
.balfour-envelope__reset:focus-visible {
  box-shadow: 0 0.6rem 1.2rem rgba(17, 19, 29, 0.2);
  transform: translateY(-0.1rem);
}

@media (max-width: 42rem) {
  .balfour-feature {
    border-radius: 1rem;
    margin-inline: -0.25rem;
  }

  .balfour-envelope-stage {
    --envelope-width: min(15.2rem, 68vw);
    min-height: 21rem;
    padding-top: 3.5rem;
  }

  .balfour-envelope-stage.is-open,
  .balfour-envelope-stage.has-opened {
    min-height: 58rem;
    padding-top: 26rem;
  }

  .balfour-envelope-stage.is-unfolded .balfour-letter {
    transform: translateY(calc(var(--envelope-width) * -0.4)) scale(1.875);
  }
}

@media (prefers-reduced-motion: reduce) {
  .balfour-envelope-stage,
  .balfour-envelope__flap,
  .balfour-letter,
  .balfour-envelope__seal {
    transition-duration: 0.01ms !important;
  }
}