input开关按钮

class="switch-btn switch-btn-animbg" type="checkbox" checked>
class="switch-btn switch-btn-animbg" type="checkbox" checked> 默认选中

.switch-btn {
  cursor: pointer;
  width: 45px;
  height: 28px;
  position: relative;
  border: 1px solid #dfdfdf;
  background-color: #fdfdfd;
  box-shadow: #dfdfdf 0 0 0 0 inset;
  border-radius: 15px;
  background-clip: content-box;
  display: inline-block;
  -webkit-appearance: none;
  user-select: none;
  outline: none; 
}
.switch-btn:before {
    content: '';
    width: 25px;
    height: 25px;
    position: absolute;
    top: 0;
    left: 0;
    border-radius: 20px;
    background-color: #fff;
    box-shadow: 0 1px 3px rgba(0, 0, 0, .4); 
}
.switch-btn:checked {
    border-color: #56b0d4;
    box-shadow: #56b0d4 0 0 0 16px inset;
    background-color: #56b0d4; 
}
.switch-btn:checked:before {
    left: 18px; 
}
.switch-btn.switch-btn-animbg {
    transition: background-color ease .4s; 
}
.switch-btn.switch-btn-animbg:before {
    transition: left .3s; 
}
.switch-btn.switch-btn-animbg:checked {
    box-shadow: #dfdfdf 0 0 0 0 inset;
    background-color: #56b0d4;
    transition: border-color .4s, background-color ease .4s; 
}
.switch-btn.switch-btn-animbg:checked:before {
    transition: left .3s; 
}