Thymeleaf: how to use conditionals to dynamically add/remove a CSS class

There is also th:classappend.

<a href="" class="baseclass" th:classappend="${isAdmin} ? adminclass : userclass"></a>

If isAdmin is true, then this will result in:

<a href="" class="baseclass adminclass"></a>

Yes, it is possible to change a CSS class dynamically according to the situation, but not with th:if. This is done with the elvis operator.

<a href="lorem-ipsum.html" th:class="${isAdmin}? adminclass : userclass">Lorem Ipsum</a>