.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: transparent;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1050;
  transition: opacity 1.5s ease, transform 1.5s ease;
}

.modal-overlay::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: calc(16 / 9 * 50vh);
  height: 50vh;
  transform: translate(-50%, -50%);
  background-color: transparent;
  box-shadow: 0 0 0 9999px rgb(255 255 255 / 85%);
  z-index: 0;
}

.modal-overlay.hidden {
  opacity: 0;
  transform: scale(5);
  pointer-events: none;
}

.container-letter {
  position: relative;
  width: calc(16 / 9 * 50vh);
  height: 50vh;
  background-color: transparent;
  z-index: 1;
  transition: transform 1s ease-in-out, opacity 1s ease-in-out;
}

@media (max-width: 768px) {

  .container-letter {
    width: calc(9 / 16 * 50vw);
    height: 50vw;
    margin: 0 auto;
  }

  .modal-overlay::before {
    width: calc(9 / 16 * 50vw);
    height: 50vw;
  }

  .cover {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    border-left: calc(9 / 16 * 80vw) solid transparent !important;
    border-right: calc(9 / 16 * 80vw) solid transparent !important;
    border-top: 26vw solid #dbcbab !important;
  }

  .paper {
    position: absolute !important;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    border-left: calc(9 / 16 * 80vw) solid #fff6e1 !important;
    border-right: calc(9 / 16 * 80vw) solid #fff6e1 !important;
    border-top: 25vw solid transparent !important;
    border-bottom: 25vw solid #fff2d4 !important;
  }

  .open-cover {
    transform: rotateX(180deg) translateX(-50%) !important;
  }

  .btn-heart {
    font-size: 1.5rem !important;
  }
}

.cover {
  position: absolute;
  width: 0;
  height: 0;
  border-left: calc(16 / 9 * 25vh) solid transparent;
  border-right: calc(16 / 9 * 25vh) solid transparent;
  border-top: 26vh solid #dbcbab;
  transition: transform 0.75s;
  transform-origin: top;
}

.open-cover {
  transform: rotateX(180deg);
}

.paper {
  position: relative;
  top: 0;
  width: 0;
  height: 0;
  border-left: calc(16 / 9 * 25vh) solid #fff6e1;
  border-right: calc(16 / 9 * 25vh) solid #fff6e1;
  border-top: 25vh solid transparent;
  border-bottom: 25vh solid #fff2d4;
  transition: all 0.75s;
  z-index: -1;
  box-shadow: 0 15px 25px rgba(0, 0, 0, 0.3);
}

.btn-heart {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 2.5rem;
  transition: opacity 0.9s ease-in, transform 0.9s ease-in;
}

.btn-heart:hover {
  background-color: #ff6b6b;
}

.container-letter.zoom-out {
  transform: scale(1);
  opacity: 0;
}

.open-btn {
  transform: scale(0.9) rotate(15deg);
  opacity: 0;
}

.no-scroll {
  overflow: hidden;
  height: 100vh;
}

#music {
  position: fixed;
  bottom: 20px;
  left: 20px;
}