/* ====================================================================
   INTERACTIVE WAX-SEALED ENVELOPE & CANVAS PETALS STYLING
   ==================================================================== */

/* Fullscreen Overlay */
.envelope-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(circle at center, #2C2622 0%, #151210 100%);
  z-index: 999999;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  transition: opacity 1.2s cubic-bezier(0.16, 1, 0.3, 1), visibility 1.2s;
}

.envelope-overlay.hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

/* 3D Perspective Container */
.envelope-perspective {
  perspective: 1200px;
  width: 100%;
  max-width: 440px;
  display: flex;
  justify-content: center;
  align-items: center;
}

/* The Envelope Container */
.envelope-box {
  position: relative;
  width: 100%;
  max-width: 380px;
  height: 250px;
  background: #EFE7DA;
  border-radius: 6px;
  box-shadow: 0 25px 50px rgba(0, 0, 0, 0.5), 0 0 0 1px rgba(197, 160, 89, 0.4);
  cursor: pointer;
  transition: transform 0.4s ease;
}

.envelope-box:hover {
  transform: translateY(-4px);
}

/* Inside Letter Card (Thiệp lồng bên trong) */
.envelope-letter {
  position: absolute;
  top: 10px;
  left: 15px;
  right: 15px;
  height: 230px;
  background: #FCFAF7;
  border: 1px solid rgba(197, 160, 89, 0.4);
  border-radius: 4px;
  padding: 1.5rem;
  text-align: center;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.08);
  transition: transform 1s cubic-bezier(0.16, 1, 0.3, 1);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 2;
}

.envelope-letter-title {
  font-family: 'Great Vibes', cursive;
  font-size: 2.2rem;
  color: #C5A059;
  line-height: 1.2;
}

.envelope-letter-subtitle {
  font-family: 'Playfair Display', serif;
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: #2D2621;
  margin: 0.5rem 0;
}

.envelope-letter-names {
  font-family: 'Cormorant Garamond', serif;
  font-size: 1.35rem;
  font-weight: 700;
  color: #9A7633;
}

/* Flaps */
.envelope-flap-bottom {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 0;
  border-style: solid;
  border-width: 0 190px 135px 190px;
  border-color: transparent transparent #E6DC melt #E6DCD0;
  border-color: transparent transparent #E2D7C8 transparent;
  z-index: 4;
}

.envelope-flap-left {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 0;
  border-style: solid;
  border-width: 125px 0 125px 190px;
  border-color: transparent transparent transparent #DDD2C3;
  z-index: 3;
}

.envelope-flap-right {
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  width: 0;
  border-style: solid;
  border-width: 125px 190px 125px 0;
  border-color: transparent #D8CCBD transparent transparent;
  z-index: 3;
}

/* Top Flap with 3D Flip */
.envelope-flap-top {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 0;
  border-style: solid;
  border-width: 140px 190px 0 190px;
  border-color: #EFE7DA transparent transparent transparent;
  transform-origin: top center;
  transition: transform 0.8s cubic-bezier(0.16, 1, 0.3, 1), z-index 0.2s 0.3s;
  z-index: 5;
}

/* Wax Seal (Con Dấu Sáp Vàng) */
.wax-seal {
  position: absolute;
  top: 130px;
  left: 50%;
  transform: translateX(-50%) translateY(-50%);
  width: 68px;
  height: 68px;
  border-radius: 50%;
  background: radial-gradient(circle at 35% 35%, #F4D38B 0%, #C5A059 55%, #8B6524 100%);
  box-shadow: 
    0 4px 15px rgba(0, 0, 0, 0.3),
    inset 0 2px 4px rgba(255, 255, 255, 0.5),
    inset 0 -2px 4px rgba(0, 0, 0, 0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 6;
  cursor: pointer;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  animation: sealPulse 2.5s infinite ease-in-out;
}

.wax-seal:hover {
  transform: translateX(-50%) translateY(-50%) scale(1.08);
  box-shadow: 0 8px 25px rgba(197, 160, 89, 0.6);
}

.wax-seal-inner {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px dashed rgba(255, 255, 255, 0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #FFFFFF;
  font-family: 'Great Vibes', cursive;
  font-size: 1.5rem;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
}

@keyframes sealPulse {
  0%, 100% {
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3), 0 0 0 0 rgba(197, 160, 89, 0.4);
  }
  50% {
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.4), 0 0 0 14px rgba(197, 160, 89, 0);
  }
}

/* Prompt Text */
.envelope-prompt {
  margin-top: 2.5rem;
  color: #E8D7B5;
  font-family: 'Cormorant Garamond', serif;
  font-size: 1.25rem;
  letter-spacing: 2px;
  text-transform: uppercase;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  animation: promptFade 2s infinite ease-in-out;
}

@keyframes promptFade {
  0%, 100% { opacity: 0.7; transform: translateY(0); }
  50% { opacity: 1; transform: translateY(-3px); }
}

/* OPENED STATE ANIMATIONS */
.envelope-box.opened .envelope-flap-top {
  transform: rotateX(180deg);
  z-index: 1;
}

.envelope-box.opened .wax-seal {
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.envelope-box.opened .envelope-letter {
  transform: translateY(-160px);
  z-index: 5;
  box-shadow: 0 15px 35px rgba(0, 0, 0, 0.3);
}

/* Falling Canvas Petals */
#petalsCanvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 9998;
  will-change: transform;
  transform: translateZ(0);
}