<p class="btn-switch">          
  <input type="radio" id="yes" name="switch" class="btn-switch__radio btn-switch__radio_yes" />
  <input type="radio" checked id="no" name="switch" class="btn-switch__radio btn-switch__radio_no" />   
  <label for="yes" class="btn-switch__label btn-switch__label_yes"><span class="btn-switch__txt">Oui</span></label>                 <label for="no" class="btn-switch__label btn-switch__label_no"><span class="btn-switch__txt">Non</span></label>             
</p>

html {
  text-align: center;
  font-family: Georgia, "Times New Roman", serif;
}
.btn-switch {
  font-size: 6em;
  position: relative;
  display: inline-block;    
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}
.btn-switch__radio {
  display: none;
}
.btn-switch__label {
  display: inline-block;  
  padding: .75em .5em .75em .75em;
  vertical-align: top;
  font-size: 1em;
  font-weight: 700;
  line-height: 1.5;
  color: #666;
  cursor: pointer;
  transition: color .2s ease-in-out;
}
.btn-switch__label + .btn-switch__label {
  padding-right: .75em;
  padding-left: 0;
}
.btn-switch__txt {
  position: relative;
  z-index: 2;
  display: inline-block;
   min-width: 1.5em;
  opacity: 1;
  pointer-events: none;
  transition: opacity .2s ease-in-out;
}
.btn-switch__radio_no:checked ~ .btn-switch__label_yes .btn-switch__txt,
.btn-switch__radio_yes:checked ~ .btn-switch__label_no .btn-switch__txt {
  opacity: 0;
}
.btn-switch__label:before {
  content: "";
  position: absolute;
  z-index: -1;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background: #f0f0f0;
  border-radius: 1.5em;
  box-shadow: inset 0 .0715em .3572em rgba(43,43,43,.05);
  transition: background .2s ease-in-out;
}
.btn-switch__radio_yes:checked ~ .btn-switch__label:before {
  background: #6ad500;
}
.btn-switch__label_no:after {
  content: "";
  position: absolute;
  z-index: 2;
  top: .5em;
  bottom: .5em;
  left: .5em;
  width: 2em;
  background: #fff;
  border-radius: 1em; 
  pointer-events: none;
  box-shadow: 0 .1429em .2143em rgba(43,43,43,.2), 0 .3572em .3572em rgba(43,43,43,.1);
  transition: left .2s ease-in-out, background .2s ease-in-out;
}
.btn-switch__radio_yes:checked ~ .btn-switch__label_no:after {
  left: calc(100% - 2.5em);
  background: #fff;
}
.btn-switch__radio_no:checked ~ .btn-switch__label_yes:before,
.btn-switch__radio_yes:checked ~ .btn-switch__label_no:before {
  z-index: 1;
}
.btn-switch__radio_yes:checked ~ .btn-switch__label_yes {
  color: #fff;
}