Changing Custom CSS to Make "X" Larger

Site URL: https://www.nationaltab.com/break-ground

Is there a way to change the CSS code on my site to make the "X" in the light room feature larger? See image attached to understand what I'm referring to. 

Add this to Design > Custom CSS

.yui3-lightbox2 .sqs-lightbox-close:before {
    font-size: 100px;
    line-height: 100px;
    width: 100px;
    height: 100px;
}