use btn-outline-secondary in place of btn-secondary-outline

[cadu-leite]

it is btn-outline-secondary and not btn-secondary-outline

the class name for outlined buttons is btn-outline-secondary
like in bootstrap samples page

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <button class="btn btn-outline-secondary" type="button">Button</button>
  </div>
  <input type="text" class="form-control" placeholder="" aria-label="" aria-describedby="basic-addon1">
</div>

see at https://getbootstrap.com/docs/4.0/components/input-group/#button-addons

and not as used in Modular-admin sample site.

<button type="button" class="btn btn-secondary-outline">Secondary</button>

[m10241]

Thanks for your comment. I think both of them are correct and the class name that you mentioned is the customized version of bootstrap. It has the styling that matches modularadmin. You can use either btn-secondary-outline to have modularadmin styling or btn-outline-secondary to have bootstrap default styling.