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

html, body {
  height: 100%;
}

body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: url("images/background.jpeg") center / cover no-repeat;
  overflow: hidden;
}

.stage {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.envelope-wrapper {
  width: min(90vw, 700px, var(--envelope-vh-cap, 74vh));
  aspect-ratio: 840 / 600;
  perspective: 2000px;
  transform: translateY(60vh);
  animation: slideInUp 1s ease-out forwards;
  cursor: default;
}

.envelope-wrapper.ready {
  cursor: pointer;
}

.envelope-wrapper.opened {
  cursor: default;
}

.envelope {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  animation: flip 2.5s ease-in-out 1s forwards;
}

.envelope .retro {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  backface-visibility: hidden;
  border-radius: 8px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
  transform: rotateY(0deg);
}

.fronte-face {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border-radius: 8px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
  backface-visibility: hidden;
  transform: rotateY(-180deg);
  perspective: 2000px;
}

.fronte-face .fronte {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.bottom-flap {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.bottom-flap img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.bottom-flap .esterno {
  z-index: 3;
}

.biglietto-wrap {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 68%;
  aspect-ratio: 1140 / 1620;
  transform: translate(-50%, -50%) rotate(-90deg);
  perspective: 1500px;
}

.envelope-wrapper.opened .biglietto-wrap {
  animation: cardOut 3s ease-in-out 1.3s forwards,
    cardGrow 1s ease-out 4.3s forwards;
}

@keyframes cardOut {
  0% {
    top: 50%;
    transform: translate(-50%, -50%) rotate(-90deg);
  }
  7% {
    /* il lembo (transition 1.5s dal click) ha finito di aprirsi: il biglietto sale sopra solo a lembo-superiore-interno */
    top: 47%;
    transform: translate(-50%, -50%) rotate(-90deg);
    z-index: 2;
  }
  45% {
    top: -70%;
    transform: translate(-50%, -50%) rotate(-90deg);
  }
  55% {
    top: -50%;
    transform: translate(-50%, -50%) rotate(0deg);
    z-index: 5;
  }
  100% {
    top: 50%;
    transform: translate(-50%, -50%) rotate(0deg);
    z-index: 5;
  }
}

@keyframes cardGrow {
  from {
    top: 50%;
    transform: translate(-50%, -50%) rotate(0deg) scale(1);
  }
  to {
    top: 50%;
    transform: translate(-50%, -50%) rotate(0deg) scale(var(--card-grow-scale, 1.15));
  }
}

.biglietto-flip {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 1s ease-in-out;
}

.biglietto-wrap.flipped .biglietto-flip {
  transform: rotateY(180deg);
}

.biglietto-flip .biglietto {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  backface-visibility: hidden;
}

.biglietto-flip .biglietto.fronte {
  transform: rotateY(0deg);
}

.biglietto-flip .biglietto.retro {
  transform: rotateY(180deg);
}

.top-flap {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%; /* fronte-busta-turchese-top.png usa l'intero canvas (631x450), a differenza del vecchio lembo-superiore-esterno.webp (840x549) */
  transform-style: preserve-3d;
  transform-origin: top center;
  transform: rotateX(0deg);
  transition: transform 1.5s ease-in-out, z-index 0s linear 1.5s;
  z-index: 4;
}

.envelope-wrapper.opened .top-flap {
  transform: rotateX(-180deg);
  z-index: 1;
}

.top-flap .esterno,
.top-flap .interno-wrap {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  backface-visibility: hidden;
}

.top-flap .esterno {
  transform: rotateX(0deg);
}

.top-flap .interno-wrap {
  transform: rotateX(180deg);
}

.top-flap .interno {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transform: rotate(180deg);
  left:1px;
}

.hint {
  margin: 0;
  color: #fff;
  font-size: 1rem;
  letter-spacing: 0.05em;
  text-shadow: 0 2px 6px rgba(0, 0, 0, 0.5);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.6s ease;
}

.envelope-wrapper.ready ~ .hint {
  opacity: 1;
  animation: hintPulse 1.8s ease-in-out infinite;
}

.envelope-wrapper.opened ~ .hint {
  opacity: 0;
  animation: none;
}

@keyframes hintPulse {
  0%, 100% {
    transform: translateY(0);
    opacity: 0.7;
  }
  50% {
    transform: translateY(-6px);
    opacity: 1;
  }
}

@keyframes flip {
  from { transform: rotateY(0deg); }
  to { transform: rotateY(-180deg); }
}

@keyframes slideInUp {
  from {
    transform: translateY(60vh);
  }
  to {
    transform: translateY(0);
  }
}

.side-panel {
  position: fixed;
  z-index: 10;
  background: #fdfdf9;
  overflow-y: auto;
  pointer-events: none;
  transition: transform 0.7s ease-in-out;
}

.panel-close {
  position: absolute;
  top: 14px;
  right: 14px;
  width: 32px;
  height: 32px;
  border: none;
  border-radius: 50%;
  background: rgba(0, 0, 0, 0.06);
  color: #555;
  font-size: 1.3rem;
  line-height: 1;
  cursor: pointer;
  z-index: 1;
}

.panel-content {
  padding: clamp(36px, 6vh, 70px) clamp(24px, 3vw, 44px);
  font-family: "Open Sans", sans-serif;
  color: #6b8f83;
  text-align: center;
}

.panel-title {
  margin: 0 0 16px;
  color: #93b34e;
  font-family: "Open Sans", sans-serif;
  font-size: clamp(1.1rem, 0.6vw + 0.85rem, 1.5rem);
  letter-spacing: 0.15em;
  font-weight: 700;
}

.panel-divider {
  border: none;
  border-top: 1px solid #e2e2dc;
  margin: clamp(14px, 2vh, 22px) 0;
}

.panel-subtitle {
  margin: 0 0 12px;
  color: #333;
  font-family: "Open Sans", sans-serif;
  font-size: clamp(0.7rem, 0.15vw + 0.62rem, 0.82rem);
  letter-spacing: 0.15em;
  font-weight: 700;
}

.panel-venue {
  margin: 0 0 10px;
  color: #93b34e;
  font-size: clamp(0.85rem, 0.25vw + 0.72rem, 1rem);
  font-weight: 700;
}

.panel-address {
  margin: 0 0 18px;
  font-size: clamp(0.72rem, 0.15vw + 0.62rem, 0.85rem);
  line-height: 1.5;
}

.panel-content p {
  margin: 0 0 16px;
  font-size: clamp(0.72rem, 0.15vw + 0.62rem, 0.85rem);
  line-height: 1.6;
}

.panel-actions {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-top: 16px;
}

.panel-link {
  color: #4a7d8c;
  text-decoration: none;
  font-size: clamp(0.72rem, 0.15vw + 0.62rem, 0.85rem);
}

.panel-link:hover {
  text-decoration: underline;
}

.rotate-btn {
  display: inline-block;
  position: fixed;
  top: clamp(24px, 6vh, 64px);
  left: clamp(24px, 6vw, 90px);
  padding: clamp(12px, 1.6vh, 18px) clamp(28px, 3vw, 46px);
  background: #93b34e;
  color: #fff;
  border: none;
  border-radius: 30px;
  font-family: "Open Sans", sans-serif;
  font-size: clamp(0.9rem, 0.5vw + 0.75rem, 1.2rem);
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  cursor: pointer;
  box-shadow: 0 6px 20px rgba(147, 179, 78, 0.55);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.6s ease 0.4s;
  z-index: 6;
}

body.showcase .rotate-btn {
  opacity: 1;
  pointer-events: auto;
  animation: rotateBtnPulse 1.8s ease-in-out 1s infinite;
}

@keyframes rotateBtnPulse {
  0%, 100% {
    transform: scale(1);
    box-shadow: 0 6px 20px rgba(147, 179, 78, 0.55);
  }
  50% {
    transform: scale(1.08);
    box-shadow: 0 8px 28px rgba(147, 179, 78, 0.85);
  }
}

.details-btn {
  display: none;
}

@media (max-width: 1024px) {
  body {
    --card-grow-scale: 1.55;
    --envelope-vh-cap: 55vh;
  }

  .side-panel {
    left: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    max-height: 78vh;
    border-radius: 20px 20px 0 0;
    box-shadow: 0 -10px 40px rgba(0, 0, 0, 0.25);
    transform: translateY(100%);
  }

  body.panel-open .side-panel {
    transform: translateY(0);
    pointer-events: auto;
  }

  .details-btn {
    display: inline-block;
    position: fixed;
    left: 50%;
    bottom: 6vh;
    transform: translateX(-50%);
    padding: 14px 34px;
    background: #93b34e;
    color: #fff;
    border: none;
    border-radius: 30px;
    font-family: "Open Sans", sans-serif;
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    cursor: pointer;
    box-shadow: 0 6px 20px rgba(147, 179, 78, 0.55);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.6s ease 0.4s;
    z-index: 6;
  }

  body.showcase .details-btn {
    opacity: 1;
    pointer-events: auto;
  }
}

@media (min-width: 1025px) {
  body {
    --panel-w: clamp(320px, 22vw, 480px);
  }

  .panel-close {
    display: none;
  }

  .stage {
    transition: transform 0.8s ease-in-out;
  }

  body.showcase .stage {
    transform: translateX(calc(var(--panel-w) / -2));
  }

  .side-panel {
    top: 0;
    right: 0;
    width: var(--panel-w);
    height: 100vh;
    box-shadow: -10px 0 40px rgba(0, 0, 0, 0.25);
    transform: translateX(100%);
    transition: transform 0.8s ease-in-out;
  }

  body.panel-open .side-panel {
    transform: translateX(0);
    pointer-events: auto;
  }
}