button {
visibility: hidden;
}
button:after {
content:'goodbye';
visibility: visible;
display: block;
position: absolute;
background-color: red;
padding: 5px;
top: 2px;
}
.pvw-title span {
display: none;
}
.pvw-title:after {
content: 'whatever it is you want to add';
}
<button>Hello</button>
button {
background-color: green;
color: black;
padding: 5px;
}