Buttons in the mobile version do not work

Good morning, I have a finished website, it works perfectly on the desktop, but in mobile mode, all the buttons do not work, the side menu is perfect, but the buttons on the pages that do not work. I am using these commands for the buttons:

<a href="research.jsp" class="btn btn-md btn-primary">MORE</a>

CSS:

btn-primary {
  color: #ffffff;
  background-color: #3314a8;
  border-color: #250d7e;
}
.btn-primary:hover {
  color: #ffffff;
  background-color: #eb3865;
  border-color: #df0038;
  -moz-transition: 0.3s all ease;
  -o-transition: 0.3s all ease;
  -webkit-transition: 0.3s all ease;
  transition: 0.3s all ease;
}
.btn-primary:active {
  background-color: #000000;
  border-color: #000000;
}