I searched, but could not find this posted on the forums.

This is the css I've just come up with, that seems to work OK.

/* Turn LOAD MORE TOPICS into button */ 
.wpf-more-topics {
    text-align: center !important;
    font-weight: 600;
    font-size: larger !important;
    background-color: yellow;
    max-width: 200px;
    margin: 0 auto !important;
    padding: 10px 0px !important;
border: solid 1px #ccc !important;
box-shadow: 1px 1px 5px #ccc !important;
transition: all 0.2s ease-in-out;}

.wpf-more-topics:hover {
box-shadow: 0px 0px 0px #ccc !important;
transition: all 0.2s ease-in-out;
}