Matching a checkbox to a custom checkbox

Ok so I made a show hide toggle checkbox for a password input. However, I cannot figure out how to get the "when checked" background of the checkbox to be a different color.

In our existing code base there is a custom checkbox that uses custom styling, however I cannot use this checkbox for this feature as it does not use ng-model. See Example Here

<input ng-show="showpassword" type="text" name="Password" id="password" ng-model="TokenLogin.Password" Class="form-control input-lg" ng-class="Loginform.Password.$invalid?'ng-dirty':''" required autofocus style="width:250px;">
<input ng-hide="showpassword" type="password" name="Password" id="password" ng-model="TokenLogin.Password" Class="form-control input-lg" ng-class="Loginform.Password.$invalid?'ng-dirty':''" required autofocus style="width:250px;">
                                
<input style="opacity: 1; color: #009688;" type="checkbox" ng-model="showpassword" ng-checked="false"> <label style="color: #a9a9a9; font-weight: 700;">Show</label>