set the class (buybtn-1,buybtn-2,buybtn-3,buybtn-4) of the object button according to the style selected by the radio box
<button type="button" class="hide" title="" ></button>
<div class="form-row">
<label class="radio-inline">
<input type="radio" v-model="buyBtnStyle" name="BBS" id="inlineRadio1" value="buyBtn1"> 1
</label>
<label class="radio-inline">
<input type="radio" v-model="buyBtnStyle" name="BBS" id="inlineRadio2" value="buyBtn2"> 2
</label>
<label class="radio-inline">
<input type="radio" v-model="buyBtnStyle" name="BBS" id="inlineRadio3" value="buyBtn3"> 3
</label>
<label class="radio-inline">
<input type="radio" v-model="buyBtnStyle" name="BBS" id="inlineRadio4" value="buyBtn4"> 4
</label>
</div>