css style not working on aspx but working on html

why does this css works when i code it with html and stay checked when i select the radio button but not when i use aspx

.btn-check:checked + .btn-secondary, .btn-check:active + .btn-secondary, .btn-secondary:active, .btn-secondary.active, .show > .btn-secondary.dropdown-toggle {    color: #fff;    background-color: #80D2DA;    border-color: #80D2DA;  }  

aspx code

<div class="col-lg-4 col-6 pt-lg-0 pt-2">                    <asp:RadioButton ID="RadioButton1" runat="server" class="btn-check"  GroupName="Testing" Text="1"  />                     <label class="btn btn-secondary w-100 p-lg-3 p-3" for="RadioButton1">above 37&deg;C</label>                  </div>  

https://stackoverflow.com/questions/67443992/css-style-not-working-on-aspx-but-working-on-html May 08, 2021 at 12:06PM