2
There is already a block for this.
Themes block in the system module.
But if you want to do it with a button, you can use the code below.
domain.com/index.php?xoops_theme_select=
XH-003
<div class="btn-group" role="group" aria-label="Basic mixed styles example">
<button type="button" class="btn btn-danger"><a href="https://domain.com/index.php?xoops_theme_select=XH-003">Tema 1</button>
<button type="button" class="btn btn-warning"><a href="https://domain.com/index.php?xoops_theme_select=XH-004">Tema 2</button>
<button type="button" class="btn btn-success"><a href="https://domain.com/index.php?xoops_theme_select=XH-005">Tema 3</button>
</div>
