[John Lester]

Add the following code to additional.css (adjust the px and color as desired)

ACP -> Styles & templates -> style manager -> your style here -> edit templates -> CSS templates -> addtional.css

.postbitlegacy .userinfo .postuseravatar img, .eventbit .userinfo .eventuseravatar img {
    border: 30px solid #021a40 !important;
    max-width: 180px;
}