tabi-test/sass/parts/_theme-switch.scss

.theme-switcher {
  align-self: center;
  margin-left: 0.5rem;
  width: 1rem;
  height: 1rem;
  position: relative;
  cursor: pointer;

  .switch {
    width: 1rem;
    height: 1rem;
    position: absolute;
    left: 0px;
    display: flex;
    justify-content: center;
    align-items: center;
    img {
      width: 100%;
      height: auto;
      position: absolute;
      border: none;
    }
    .sun {
      opacity: 0;
    }
    .moon {
      opacity: 1;
    }
  }
  input {
    display: none;
    &:checked + .switch {
      .sun {
        opacity: 1;
      }
      .moon {
        opacity: 0;
      }
    }
  }
}