.btn {
  --btn-image-size: 2.65em;

  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  gap: 0.5em;
  padding: var(--btn-padding, 0.5em 1.1em);
  border: var(--btn-border-size, 1px) solid var(--btn-border-color, var(--color-border--heavy));
  border-radius: var(--btn-border-radius, 2em);
  background-color: var(--btn-background, var(--color-text--reversed));
  color: var(--btn-color, var(--color-text));
  font-family: inherit;
  line-height: inherit;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;

  &:active {
    filter: brightness(0.75);
  }

  &:focus-within,
  &:focus-visible {
    box-shadow:
      0 0 0 2px var(--btn-focus-inner, var(--color-text--reversed)),
      0 0 0 4px var(--btn-focus-outer, var(--btn-background));
  }

  &:focus:not(:focus-visible) {
    box-shadow: none;
  }

  &:where(:not(:is(.avatar):has(img))) {
    text-align: start;

    & img {
      max-inline-size: unset;
      inline-size: 1.3em;
    }

    & img:not([class]) {
      filter: invert(0);

      @media (prefers-color-scheme: dark) {
        filter: invert(100%);
      }
    }
  }

  &:where(:has(.for-screen-reader):has(img)) {
    --btn-border-radius: 50%;
    --btn-padding: 0;

    inline-size: var(--btn-image-size);
    block-size: var(--btn-image-size);
    display: grid;
    place-items: center;
    aspect-ratio: 1;

    > * {
      grid-area: 1/1;
    }
  }

  &:where(:is(.avatar)) {
    --btn-border-radius: var(--avatar-border-radius);
    --btn-padding: 0;
    --btn-border-size: 0;

    justify-content: unset;

    & img {
      inline-size: 100%;
    }
  }

  &:where(:is(summary)) {
    list-style: none;

    &::marker,
    &::-webkit-details-marker { display: none; }
  }

  & img {
    user-select: none;
    -webkit-touch-callout: none;
  }

  [data-submitting] &[data-form-target] {
    position: relative;

    > * { visibility: hidden; }

    &::after {
      --mask: no-repeat radial-gradient(#000 68%,#0000 71%);
      --size: 1.25em;

      content: "";
      width: var(--size);
      aspect-ratio: 8/5;
      inset: 50%;
      position: absolute;
      margin-inline: calc((var(--size) / 2) * -1);
      margin-block: calc((var(--size) / 3) * -1);
      -webkit-mask: var(--mask), var(--mask), var(--mask);
      -webkit-mask-size: 28% 45%;
      background: currentColor;
      animation: submitting 1s infinite linear;
    }
  }

  &:disabled {
    filter: saturate(0.7) brightness(0.7);

    &::after { opacity: 0.7; }
  }

  &:has(input:checked),
  &[aria-checked="true"] {
    --btn-background: var(--color-text);
    --btn-color: var(--color-text--reversed);

    & img {
      filter: invert(100%);
    }

    @media (prefers-color-scheme: dark) {
      & img {
        filter: invert(0);
      }
    }
  }
}

.btn--primary {
  --btn-background: var(--color-text);
  --btn-color: var(--color-text--reversed);
  --btn-border-color: var(--color-text--reversed);
}

.btn--reversed {
  --btn-background: var(--color-text);
  --btn-color: var(--color-text--reversed);
}

.btn--negative {
  --btn-background: var(--color-negative);
  --btn-color: var(--color-text--reversed);
  --btn-focus-outer: var(--color-negative);
  --btn-border-color: var(--color-text--reversed);
}

.btn--borderless {
  --btn-border-color: transparent;
}

.btn--plain {
  --btn-background: transparent;
  --btn-border-color: transparent;
  --btn-padding: 0;
}

:is(.btn--primary, .btn--reversed, .btn--negative) {
  & img:not(.avatar) {
    filter: invert(100%);

    @media (prefers-color-scheme: dark) {
      filter: invert(0%);
    }
  }
}

.btn--success {
  animation: success 1s ease-out;

  & img {
    animation: zoom-fade 300ms ease-out;
  }
}