.mask-thoughtbubble {
    mask-image: url(../files/images/clippingmasks/thought_bubble_mask_inverted.png);
    mask-position: center;
    mask-size:contain;
    -webkit-mask-image: url(../files/images/clippingmasks/thought_bubble_mask_inverted.png);
    -webkit-mask-position: center;
    -webkit-mask-size:contain;
}