<div class="cp_ipradio03">
  <input type="radio" name="cpipr03" id="a_rb1" />
  <label for="a_rb1">ネコ</label>
  <input type="radio" name="cpipr03" id="a_rb2" />
  <label for="a_rb2">イヌ</label>
  <input type="radio" name="cpipr03" id="a_rb3" />
  <label for="a_rb3">ウサギ</label>
</div>

.cp_ipradio03 {
  margin: 2em auto;
  display: flex;
}
/*デフォルトのラジオボタンの設定*/
.cp_ipradio03 input[type='radio'] {
  display: none;
}
/*通常時のラジオボタンの設定*/
.cp_ipradio03 label {
  position: relative;
  display: flex;
  align-items: center;
  margin-right: 20px;
  padding-left: 35px;
  padding-right: 10px;
  cursor: pointer;
  z-index: 99;
}
.cp_ipradio03 label::before {
  position: absolute;
  left: 0;
  content: '';
  display: block;
  width: 24px;
  height: 24px;
  border: 2px solid #da3c41;
  border-radius: 4px;
  z-index: -1;
}
/* Transition */
.cp_ipradio03 label,
.cp_ipradio03 label::before {
  transition: 0.25s all ease;
}
/*ラジオボタンの設定*/
.cp_ipradio03 input[type='radio'] + label::before {
  border-radius: 20px;
}
/*checked時のサイズと色の設定*/
.cp_ipradio03 input[type='radio']:checked + label {
  padding-left: 10px;
  color: #ffffff;
}
.cp_ipradio03 input[type='radio']:checked + label::before {
  width: 100%;
  height: 100%;
  background: #da3c41;
}