How to add border to the author box

Hey there, I'm using the hook element for author box. It's working fine.

But when I'm using this CSS:

/*for author box*/
.author-box {
display: -webkit-box;
display: -ms-flexbox;
display: flex;
-ms-flex-wrap: wrap;
flex-wrap: wrap;
padding: 4%;
margin-top: 60px;
font-size: 0.8em;
}

.author-links a {
font-size: 3em;
line-height: 0.5em;
float: right;
}

.author-box .avatar {
width: 30px;
border-radius: 100%;
margin-right: 20px;
}

h5.author-title {
margin-bottom: 0.5em;
}
/*css for author box ends*/

The borders aren't appearing around the author box. I need to just add solid border around the author box.

Help me tweak the CSS.