.dt-button-collection a.buttons-columnVisibility:before, .dt-button-collection a.buttons-columnVisibility.active span:before
{
    display: block;
    position: absolute;
    top: 1.2em;
    left: 0;
    width: 12px;
    height: 12px;
    box-sizing: border-box;
}

.dt-button-collection a.buttons-columnVisibility:before {
    content: ' ';
    margin-top: -6px;
    margin-left: 10px;
    border: 1px solid black;
    border-radius: 3px;
}

.dt-button-collection a.buttons-columnVisibility.active span:before {
    content: '\2714';
    margin-top: -11px;
    margin-left: 12px;
    text-align: center;
    text-shadow: 1px 1px #DDD, -1px -1px #DDD, 1px -1px #DDD, -1px 1px #DDD;
}

.dt-button-collection a.buttons-columnVisibility span {
    margin-left: 20px;
}