message: style: use BEM style
diff: @component-namespace z {
  - @component switch {
  + @b switch {
  height: 29px;
  width: 49px;
  display: inline-block;
  position: relative;
  border: 1px solid;
  - @descendent node {
  + @e node {
  width: 27px;
  height: 27px;
  border-radius: 100%;
  