If you press f12 when you are on that page you can choose that area and see the css that controls the looks of it. It is the easiest way to see what you need to change.
Hopefully, this will be a good starting point for you. You should be able to change those settings.
.TagTiles {
list-style-type: none;
padding: 0;
margin: 0;
overflow: hidden;
}
.TagTile.colored, .TagTile.colored a {
color: #fff;
}
.TagTile-info {
top: 0;
bottom: 42px;
padding-right: 20px;
transition: background .2s;
overflow: auto;
}
.TagTile-name {
font-size: 18px;
margin: 0 0 10px;
font-weight: bold;
}
.TagTile.colored .TagTile-lastPostedDiscussion {
color: rgba(255,255,255,0.7);
}
.TagCloud {
margin-top: 30px;
text-align: center;
font-size: 16px;
line-height: 1.6;
}