flame/client/src/components/UI/Checkbox/Checkbox.module.css

.Checkbox {
  position: relative;
  display: inline-block;
  width: 20px;
  height: 20px;
  background-color: var(--color-primary);
  border-radius: 4px;
  margin: 8px 0;
  cursor: pointer;
}

.Checkbox.Checked::after {
  content: '';
  display: block;
  position: absolute;
  top: 3px;
  left: 3px;
  width: 14px;
  height: 14px;
  background-color: var(--color-background);
  border-radius: 3px;
}

.Checkbox > input {
  visibility: hidden;
}