Event Change Soure TextURL to a Button

To change event source text/url.

to a button, like this.

You can use this code to Website Tools > Custom CSS.

/* Source */
.eventitem-sourceurl {
    font-size: 0;
}
.eventitem-sourceurl a:before {
    content: "Click Me";
    color: #e35c2d;
    font-size: 16px;
    border: 2px solid #e35c2d;
    padding: 10px 40px;
}