Изучите верстку шаблона и примера тщательно.
навскидку сделайте так
#main .thumb > h2 {
-webkit-transition: all 0.15s ease-in-out;
-moz-transition: all 0.15s ease-in-out;
-o-transition: all 0.15s ease-in-out;
-ms-transition: all 0.15s ease-in-out;
transition: all 0.15s ease-in-out;
width: 100%;
left: 0!important;
top: 100%!important;
bottom: -30%!important;
text-align: center;
background: black;
color: white!important;
opacity: 0;
padding: 2rem;
}
#main .thumb:hover > h2 {
bottom: 0!important;
top: auto!important;
opacity: 1;
}