<div class="cp_ipradio06">
  <ul>
    <li class="list_item">
      <label><input type="radio" class="option-input" name="cpipr06" checked >ネコ</label>
    </li>
    <li class="list_item">
      <label><input type="radio" class="option-input" name="cpipr06">イヌ</label>
    </li>
    <li class="list_item">
      <label><input type="radio" class="option-input" name="cpipr06">ウサギ</label>
    </li>
  </ul>
</div>

.cp_ipradio06 {
  margin: 2em auto;
}
.cp_ipradio06 ul {
  list-style: none;
}
.cp_ipradio06 .list_item {
  margin-bottom: 10px;
}
/*ラベルの設定*/
.cp_ipradio06 label {
  position: relative;
  display: flex;
  align-items: center;
  cursor: pointer;
}
/*ラジオボタンの設定*/
.cp_ipradio06 .option-input {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 22px;
  /*デフォルト値を無効に*/
  border: none;
  outline: none;
  appearance: none;
}
.cp_ipradio06 .option-input:before,
.cp_ipradio06 .option-input:after {
  position: absolute;
  content: '';
  width: 20px;
  height: 20px;
  border-radius: 50%;
}
.cp_ipradio06 .option-input:before {
  background: #ffffff;
}
.cp_ipradio06 .option-input:after {
  outline: 2px solid #da3c41;
  transition: all 0.3s ease-in-out;
}
/*checked時の設定*/
.cp_ipradio06 .option-input:checked:after {
  outline: 12px solid #da3c41;
  outline-offset: -10px;
}