Here's the CSS class for that
.DiscussionList-loadMore {
text-align: center;
margin-top: 10px;
}
EDIT - the actual "button" class is here
.Button {
}
So, if you wanted to target just this button, you'd use something like the below
.DiscussionList-loadMore button {
background: red;
}
What do you want to change exactly, @wwwn ?