fizzy/app/assets/stylesheets/popup.css

@layer components {
  .popup {
    --panel-border-radius: 0.5em;
    --panel-padding: var(--block-space);
    --panel-size: auto;

    inline-size: auto;
    inset: 0 auto auto 50%;
    min-inline-size: min(25ch, 90vw);
    max-inline-size: min(50ch, 90vw);
    position: absolute;
    transform: translateX(-50%);
    z-index: var(--z-popup);

    &[open] {
      display: flex;
    }

    #header:has(&) {
      max-inline-size: 100vw;
      position: relative;
      z-index: 5;

      .popup {
        min-inline-size: 40ch;
        max-inline-size: 40ch;
      }
    }

    .card & {
      min-inline-size: 25ch;
      max-inline-size: 25ch;
    }
  }

  .popup__group {
    background: var(--color-ink-lightest);
    max-inline-size: 100%;
    padding-inline: var(--inline-space);

    .btn {
      --btn-background: transparent;
    }

    @media (any-hover: hover) {
      &:hover {
        background: var(--color-selected);
      }
    }

    &:has(:focus-visible) {
      background: var(--color-selected-dark);

      .popup__item {
        --outline-size: 0;
      }
    }
  }

  .popup__item {
    --btn-background: var(--color-ink-lightest);
    --btn-border-radius: 0.3em;
    --btn-border-size: 0;
    --btn-font-weight: 500;
    --btn-padding: var(--inline-space-half) 0 var(--inline-space-half) var(--inline-space);
    --hover-size: 0;
    --outline-color: transparent;

    flex: 1 1 auto;
    justify-content: start;
    max-inline-size: 100%;
    text-align: start;

    @media (any-hover: hover) {
      &:where(:not(:active):hover) {
        --btn-background: var(--color-selected);
      }
    }

    &:has(input:checked)  {
      --btn-background: var(--color-ink-lightest);
      --btn-color: var(--color-ink);

      .icon {
        &.checked {
          block-size: 1em;
          display: block;
          inline-size: 1em;
          margin-inline-end: var(--inline-space);
        }
      }

      @media (any-hover: hover) {
        &:where(:not(:active):hover) {
          --btn-background: var(--color-selected);
        }
      }
    }
  }

  .popup__list {
    max-block-size: 40dvh;
    overflow: auto;
    row-gap: 2px;
  }

  .popup__new {
    --btn-icon-size: 1em;

    .icon {
      margin-inline-end: 0.5em;
    }

    padding-inline-start: var(--inline-space-half);
  }

  .popup__title {
    font-weight: 800;
  }
}

.popup--animated {
  --backdrop-speed: 150ms;
  --panel-size: max-content;
  --speed: 150ms;

  opacity: 0;
  transform: scale(0.2) translateX(-50%);
  transform-origin: top left;
  transition:
      display var(--speed) allow-discrete,
      opacity var(--speed),
      overlay var(--speed) allow-discrete,
      transform var(--speed);

  &::backdrop {
    background-color: var(--color-always-black);
    opacity: 0;
    transform: scale(1);
    transition:
      display var(--backdrop-speed) allow-discrete,
      opacity var(--backdrop-speed),
      overlay var(--backdrop-speed) allow-discrete;
  }

  &[open] {
    opacity: 1;
    transform: scale(1) translateX(-50%);

    &::backdrop {
      opacity: 0.5;
    }
  }

  @starting-style {
    &[open] {
      opacity: 0;
      transform: scale(0.2) translateX(-50%);
    }

    &[open]::backdrop {
      opacity: 0;
    }
  }
}