main.scss

@import "prefixes";

body {
  height: 100vh;
  background-color: #f6f6f6;
  text-align: center;
  font-size: 3vmin;
}

.card {
  width: 80vmin;
  height: 80vmin;
  position: absolute;
  @include perspective(500vmin);
  top: 50%;
  left: 50%;
  margin: -40vmin 0 0 -40vmin;
  cursor: pointer;
}

.card:hover .face {
  @include transition(all 0.3s ease-out);
}

.face {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  @include backface-visibility(visible);
  @include transition(all 0.5s ease-out);
  @include transform-origin(0 0);
  @include box-shadow(0px 5px 20px 0px rgba(0,0,0,0.1));
}

.front {
  @include transform(rotateY(-20deg));
  z-index: 2;
  background-color: #ccc;
  background-position: center;
  @include background-size(cover);
}

.back {
  background-color: #fff;
  @include transform(rotateY(0deg));
  z-index: 1;
  overflow: auto;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  background-size: contain;
  background-position: center;
  background-repeat: no-repeat;
}

.card:hover .front {
  @include transform(rotateY(-35deg));
}

#open_card {
  display: none;

  &:checked {
    & + .card {

      .front{
        @include transform(rotateY(-165deg));

        span {
          background-color: rgba(#fff,0.95);
          position: absolute;
          top: 0;
          right: 0;
          bottom: 0;
          left: 0;
          @include transform(scale(-1, 1));
          background-size: contain;
          background-position: right bottom;
          background-repeat: no-repeat;
        }
      }
    }

    .back {
      @include transform(rotateY(-15deg));
    }
  }
}

.to,
.stamp,
.message {
  padding: 2vmin;

  p {
    margin-top: 0.25em;
    margin-bottom: 0.25em;
  }

  :first-child {
    margin-top: 0;
  }

  :last-child {
    margin-bottom: 0;
  }
}

.to,
.message {
  font-family: 'Dawning of a New Day', cursive;
}

.stamp {
  width: 100%;
}