<ul class="fs-8" id="select-product-app">
<li class="chose-btns-contianer">25</li>
<li class="chose-btns-contianer">26</li>
<li class="chose-btns-contianer">27</li>
<li class="chose-btns-contianer">28</li>
<li class="chose-btns-contianer">29</li>
<li class="chose-btns-contianer">30</li>
</ul>
as shown in the code, how to add a btn-active class for li after vue is clicked, and click something else to switch back and forth?