siyuan/app/src/assets/scss/component/_switch.scss

.b3-switch {
  flex-shrink: 0;
  -webkit-appearance: none;
  width: 36px;
  height: 20px;
  border: 1px solid var(--b3-switch-border);
  border-radius: var(--b3-border-radius-b);
  margin: 0;
  outline: none;
  display: inline-block;
  position: relative;
  cursor: pointer;
  background-color: var(--b3-switch-background);
  overflow: inherit;
  user-select: none;

  &--side {
    margin-right: 14px;
    margin-left: 14px;
  }

  &--menu {
    margin: 2px 2px 2px 0;
    align-self: center;
  }

  &:after {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    pointer-events: none;
    z-index: 1;
    content: "";
    background-color: var(--b3-switch-border);
    display: block;
    left: 9px;
    position: absolute;
    top: 50%;
    transform: translate(-50%, -50%);
    transition: left 80ms linear, background-color 80ms linear, width 80ms linear, height 80ms linear;
  }

  &:before {
    z-index: 2;
    content: "";
    left: 9px;
    position: absolute;
    top: 50%;
    transform: translate(-50%, -50%);
    width: 24px;
    height: 24px;
    background-color: var(--b3-switch-hover);
    display: none;
    border-radius: 50%;
    transition: background-color 80ms linear;
  }

  &:checked {
    background-color: var(--b3-switch-checked-background);
    border-color: transparent;

    &:after {
      background-color: var(--b3-switch-checked);
      height: 16px;
      width: 16px;
    }

    &:before,
    &:after {
      left: 25px;
    }

    &:hover:not(:disabled) {
      &:after {
        background-color: var(--b3-switch-checked-hover);
      }

      &:before {
        background-color: var(--b3-switch-checked-hover2);
      }
    }

    &:active:not(:disabled):after {
      height: 18px;
      width: 18px;
    }
  }

  &:disabled {
    opacity: .38;
    cursor: auto;
  }

  &:active:not(:disabled):after {
    height: 14px;
    width: 14px;
  }

  &:hover:not(:disabled):before {
    display: inline-block;
  }
}