* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  background: #fff;
  padding: calc(env(safe-area-inset-top, 16px) + 32px) 16px env(safe-area-inset-bottom, 16px);
  font-family: 'Quicksand', system-ui, -apple-system, sans-serif;
}

#bgLayer {
  position: fixed;
  inset: 0;
  overflow: hidden;
  z-index: -2;
}

#bgPhotoBlur {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: blur(35px) brightness(0.9);
  transform: scale(1.15);
}

#bgPhoto {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
}

#bgOverlay {
  position: fixed;
  inset: 0;
  background: rgba(255, 255, 255, 0.55);
  -webkit-backdrop-filter: blur(1.5px);
  backdrop-filter: blur(1.5px);
  z-index: -1;
}

h1 {
  margin: 0;
  font-size: 2.4rem;
  line-height: 1.2;
  font-weight: 700;
  text-align: center;
  color: #222;
  text-shadow:
    0 0 14px rgba(255, 255, 255, 0.95),
    0 0 6px rgba(255, 255, 255, 0.95),
    0 1px 3px rgba(255, 255, 255, 0.9);
}

#countdownScene,
#cardArea {
  flex: 1;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 24px;
}

#countdownScene[hidden],
#cardArea[hidden] {
  display: none;
}

.countdown-label {
  margin: 0;
  font-size: 1.1rem;
  font-weight: 600;
  color: #222;
  text-align: center;
  text-shadow:
    0 0 10px rgba(255, 255, 255, 0.95),
    0 0 4px rgba(255, 255, 255, 0.95);
}

#countdownTimer {
  display: flex;
  gap: 14px;
}

.countdown-unit {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  background: rgba(255, 255, 255, 0.75);
  border-radius: 14px;
  padding: 14px 12px;
  min-width: 64px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
}

.countdown-unit span {
  font-size: 2rem;
  font-weight: 700;
  color: #222;
  font-variant-numeric: tabular-nums;
}

.countdown-unit label {
  font-size: 0.7rem;
  font-weight: 600;
  color: #666;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

#skipCountdownBtn {
  margin-top: 4px;
  font-family: 'Quicksand', system-ui, -apple-system, sans-serif;
  font-size: 0.8rem;
  font-weight: 600;
  color: rgba(255, 255, 255, 0.85);
  background: none;
  border: none;
  text-shadow: 0 1px 3px rgba(0, 0, 0, 0.5);
  cursor: pointer;
  opacity: 0.7;
}

#cardScene {
  width: 55%;
  max-width: 420px;
  aspect-ratio: 4 / 3;
  perspective: 1200px;
  opacity: 0;
  animation: cardIntro 1.1s ease-out forwards;
  transition: height 0.8s ease;
}

#cardFlip {
  position: relative;
  width: 100%;
  height: 100%;
  -webkit-transform-style: preserve-3d;
  transform-style: preserve-3d;
  transition: -webkit-transform 0.8s ease;
  transition: transform 0.8s ease;
}

#cardFlip.idle-tilt {
  animation: cardTilt 3.6s ease-in-out infinite;
}

#cardFlip.flipped {
  -webkit-transform: rotateY(180deg);
  transform: rotateY(180deg);
}

.card-face {
  position: absolute;
  inset: 0;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
}

.card-front img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.card-back {
  position: absolute;
  top: 50%;
  left: 50%;
  right: auto;
  bottom: auto;
  width: min(85vw, 480px);
  -webkit-transform: translate(-50%, -50%) rotateY(180deg);
  transform: translate(-50%, -50%) rotateY(180deg);
  background: #fff;
  border: 2px solid #ccc;
  border-radius: 24px;
  padding: 20px;
  max-height: 62vh;
  overflow: hidden;
}

.card-back p {
  margin: 0;
  font-weight: 600;
  line-height: 1.55;
  color: #333;
  text-align: center;
}

@keyframes cardIntro {
  0% {
    opacity: 0;
    transform: rotate(-6deg) scale(0.9);
  }
  60% {
    opacity: 1;
  }
  100% {
    opacity: 1;
    transform: rotate(0deg) scale(1);
  }
}

@keyframes cardTilt {
  0%, 100% {
    transform: rotate(0deg);
  }
  25% {
    transform: rotate(-3deg);
  }
  75% {
    transform: rotate(3deg);
  }
}

#flipBtn {
  font-family: 'Quicksand', system-ui, -apple-system, sans-serif;
  font-size: 17px;
  font-weight: 600;
  padding: 10px 28px;
  border: 1px solid #999;
  border-radius: 8px;
  background: #fafafa;
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.6s ease;
}

#flipBtn.visible {
  opacity: 1;
  pointer-events: auto;
}

@media (min-width: 700px) {
  h1 {
    font-size: 3.2rem;
    max-width: 700px;
  }

  #cardScene {
    max-width: 560px;
  }

  .card-back {
    width: min(70vw, 640px);
  }

  .card-back p {
    line-height: 1.6;
  }

  #flipBtn {
    font-size: 21px;
    padding: 13px 34px;
  }

  .countdown-label {
    font-size: 1.4rem;
  }

  .countdown-unit {
    min-width: 90px;
    padding: 20px 16px;
    border-radius: 18px;
  }

  .countdown-unit span {
    font-size: 3rem;
  }

  .countdown-unit label {
    font-size: 0.85rem;
  }
}