@property --tx {
  syntax: "<percentage>";
  inherits: false;
  initial-value: 0%;
}

#manual {
  display: grid;
  grid-area: manual;
  grid-template-areas: "pages";
  justify-self: center;
  isolation: isolate;
  position: relative;
  z-index: 10;

  --default-ty: 1rem;
  --left: 0;
  --top: 0;
  --ty: 1rem;

  --animation-time: 0.5s;
  --font-size: 0.6rem;
  --height: 37rem;
  --line-height: 1;
  --padding: 2rem;
  --paper-color: oklch(0.8 0 0);
  --width: 100dvw;

  @media (min-width: 600px) {
    --font-size: 0.75rem;
    --height: 48rem;
    --line-height: 1.25;
    --manual-top: 4vh;
    --padding: 4rem;
    --width: 37rem;
  }

  * {
    font-size: var(--font-size);
    font-weight: 400;
  }

  p,
  h2,
  h3,
  li {
    margin-block-end: 1rem;
  }

  p,
  li {
    line-height: var(--line-height);
  }

  h3 {
    text-transform: uppercase;
  }

  ul {
    list-style-type: '- ';
    list-style-position: inside;
  }

  footer p {
    display: grid;
    line-height: 1.5;
  }

  img {
    position: relative;
    top: 1rem;
  }

  .page {
    box-shadow: 0 0 1rem oklch(0.1 0 0 / 0.5);
    color: black;
    cursor: pointer;
    font-family: 'Special Elite', 'Courier', monospace;
    grid-area: pages;
    height: var(--height);
    padding: var(--padding);
    position: absolute;
    transform: translateX(var(--tx)) translateY(var(--ty)) rotateZ(var(--tr));
    transition: all 0.3s cubic-bezier(.67, .31, .15, .96);
    width: var(--width);
    will-change: transform;
  }

  .page-1 {
    --manual-top: -1vh;
    --tx: -52%;
    --ty-hover: -3%;
    --tr: -1deg;
    --tr-hover: -1.5deg;

    @media (min-width: 600px) {
      --manual-top: 4vh;
      --tx: -60%;
    }

    background:
      url(../img/stain-1.png) no-repeat bottom left,
      url(../img/stain-2.png) no-repeat 170% -25%,
      var(--paper-color);
    background-size: 33%, 60%;
    z-index: 2;

    &:hover:not(.open) {
      transform: translateX(var(--tx)) translateY(var(--ty-hover)) rotateZ(var(--tr-hover));
    }

    &::before {
      background: url(../img/paper.jpeg) no-repeat center center fixed;
      background-size: cover;
      content: '';
      height: 100%;
      left: 0;
      opacity: 0.5;
      position: absolute;
      top: 0;
      width: 100%;
      z-index: -1;
    }

    &.swapping {
      animation: swapping-left var(--animation-time) ease-in-out;
    }
  }

  .page-2 {
    --manual-top: 17vh;
    --tr: 2deg;
    --tx: -45%;

    @media (min-width: 600px) {
      --manual-top: 5vh;
      --tx: -40%;
    }

    background:
      url(../img/stain-3.png) no-repeat 250% 160%,
      var(--paper-color);
    background-size: 80%;
    z-index: 1;

    &::before {
      background: url(../img/paper.jpeg) no-repeat center center fixed;
      background-size: cover;
      content: '';
      height: 100%;
      left: 0;
      opacity: 0.5;
      position: absolute;
      top: 0;
      transform: rotateZ(180deg);
      width: 100%;
      z-index: -1;
    }

    &.swapping {
      animation: swapping-right var(--animation-time) ease-in-out;
    }
  }

  .top {
    z-index: 5;
  }
}

@keyframes swapping-left {
  0% {
    --tx: -60%;
  }

  50% {
    --tx: -110%;
  }

  100% {
    --tx: -60%;
  }
}

@keyframes swapping-right {
  0% {
    --tx: -40%;
  }

  50% {
    --tx: 10%;
  }

  100% {
    --tx: -40%;
  }
}