@import "https://unpkg.com/open-props/easings.min.css";
@import "https://unpkg.com/open-props/animations.min.css";

@layer demo {
  [id="$demo"] > :nth-child(1 of span) { view-transition-name: n1 }
  [id="$demo"] > :nth-child(2 of span) { view-transition-name: n2 }
  [id="$demo"] > :nth-child(3 of span) { view-transition-name: n3 }
  [id="$demo"] > :nth-child(4 of span) { view-transition-name: n4 }
  
  [id="$demo"] > comma { view-transition-name: output-comma }
  output > sup         { view-transition-name: output-prefix }
  
  @media (prefers-reduced-motion: no-preference) {
    ::view-transition-old(n1),
    ::view-transition-old(n2),
    ::view-transition-old(n3),
    ::view-transition-old(n4),
    ::view-transition-old(output-comma):only-child {
      inline-size: fit-content;
      animation: 
        var(--animation-fade-out) forwards,
        var(--animation-slide-out-up) forwards;
    }
    
    ::view-transition-old(n1):only-child,
    ::view-transition-old(n2):only-child,
    ::view-transition-old(n3):only-child,
    ::view-transition-old(n4):only-child {
      display: none;
    }

    ::view-transition-new(n1),
    ::view-transition-new(n2),
    ::view-transition-new(n3),
    ::view-transition-new(n4),
    ::view-transition-new(output-comma):only-child {
      animation: 
        var(--animation-fade-out) reverse,
        var(--animation-slide-in-up);
    }
    
    /* stagger with an increased animation duration */
    ::view-transition-old(n1), 
    ::view-transition-new(n1) {
      animation-duration: .5s;
    }
    
    ::view-transition-old(n2), 
    ::view-transition-new(n2) {
      animation-duration: .6s;
    }
    
    ::view-transition-old(n3),
    ::view-transition-new(n3) {
      animation-duration: .7s;
    }
    
    ::view-transition-old(n4),
    ::view-transition-new(n4) {
      animation-duration: .8s;
    }
  }
}

@layer demo.support {
  * {
    box-sizing: border-box;
    margin: 0;
  }

  html {
    block-size: 100%;
    color-scheme: dark light;
    
    view-transition-name: none;
  }
  
  ::view-transition {
    pointer-events: none;
  }

  body {
    min-block-size: 100%;
    font-family: system-ui, sans-serif;

    display: grid;
    place-content: center;
    place-items: center;
  }
  
  output {
    position: relative;
    font-size: 25vmin;
    
    & > sup {
      font-size: .5ch;
      opacity: .75;
      line-height: 2.5;
      position: absolute;
      inset-inline-start: -1ch;
    }
  }
  
  [id="$demo"] {
    font-variant: tabular-nums;
    display: flex;
    gap: .1ch;
    
    > span:empty { 
      display: none;
    }
  }
  
  fieldset {
    display: flex;
    gap: 2ch;
    border: none;
  }
  
  input[type="number"] {
    max-inline-size: 8ch;
  }
  
  .no-support {
    display: none;
  }
}