Custom Styling Checkboxes: The Modern Way (The Butterfield Way)

checkbox.css

:root {
  --checkbox-border-color: #8b8c89;
  --checkbox-checked-color: #274c77;
  --checkbox-hover-color: #a3cef1;
  --checkbox-disabled-bg-color: #d9d9d9;
}

input[type="checkbox"] {
  box-sizing: border-box;
  width: 20px;
  height: 20px;
  margin: 6px;
  padding: 0;
  border: 2px solid var(--checkbox-border-color);
  appearance: none;
  background-color: transparent;
  outline: none;
  transition: outline 0.1s;
}

input[type="checkbox"]:checked {
  background-size: cover;
  padding: 2px;
}

input[type="checkbox"]:not(:disabled):checked {
  border-color: var(--checkbox-checked-color);
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="20" height="20" viewBox="0 0 32 32" xml:space="preserve"><path style="fill: %23274c77" d="M11.941,28.877l-11.941-11.942l5.695-5.696l6.246,6.246l14.364-14.364L32,8.818"/></svg>');
}

input[type="checkbox"]:disabled {
  background-color: var(--checkbox-disabled-bg-color);
}

input[type="checkbox"]:disabled:checked {
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="20" height="20" viewBox="0 0 32 32" xml:space="preserve"><path style="fill: %238b8c89" d="M11.941,28.877l-11.941-11.942l5.695-5.696l6.246,6.246l14.364-14.364L32,8.818"/></svg>');
}

@media (hover: hover) {
  input[type="checkbox"]:not(:disabled):hover {
    background-color: var(--checkbox-hover-color);
    outline: 6px solid var(--checkbox-hover-color);
    transform: scale(1.05);
  }
}

input[type="checkbox"]:focus-visible {
  outline: 6px solid var(--checkbox-hover-color);
  transform: scale(1.05);
}

@media (prefers-reduced-motion: reduce) {
  input[type="checkbox"] {
    transition: none;
  }
}

checkbox.scss

$checkbox-border-color: #8b8c89;
$checkbox-checked-color: #274c77;
$checkbox-hover-color: #a3cef1;
$checkbox-disabled-bg-color: #d9d9d9;

input[type="checkbox"] {
  box-sizing: border-box;
  width: 20px;
  height: 20px;
  margin: 6px;
  padding: 0;
  border: 2px solid $checkbox-border-color;
  appearance: none;
  background-color: transparent;
  outline: none;
  transition: outline 0.1s;

  &:checked {
    background-size: cover;
    padding: 2px;
    border-color: $checkbox-checked-color;
    background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="20" height="20" viewBox="0 0 32 32" xml:space="preserve"><path style="fill: #{$checkbox-checked-color}" d="M11.941,28.877l-11.941-11.942l5.695-5.696l6.246,6.246l14.364-14.364L32,8.818"/></svg>');
  }

  &:disabled {
    background-color: $checkbox-disabled-bg-color;

    &:checked {
      background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="20" height="20" viewBox="0 0 32 32" xml:space="preserve"><path style="fill: #{$checkbox-border-color}" d="M11.941,28.877l-11.941-11.942l5.695-5.696l6.246,6.246l14.364-14.364L32,8.818"/></svg>');
    }
  }

  @media (hover: hover) {
    &:not(:disabled):hover {
      background-color: $checkbox-hover-color;
      outline: 6px solid $checkbox-hover-color;
      transform: scale(1.05);
    }
  }

  &:focus-visible {
    outline: 6px solid $checkbox-hover-color;
    transform: scale(1.05);
  }

  @media (prefers-reduced-motion: reduce) {
    transition: none;
  }
}