Found various answers by some digging around so here is some CSS code in case this helps anyone:
/* make bakground opaque. */
#fancybox-overlay { opacity: 1 !important; }
/* color background white */
#fancybox-overlay { background : rgba(255, 255, 255, 1) !important ; }
/* nav arrows outside box always on: */
#fancybox-left-ico, #fancybox-left:hover span { left: -40px; }
#fancybox-right-ico, #fancybox-right:hover span { right: -40px; left: auto; }
/* hide fancybox nav arrows: */
#fancybox-left:hover span { visibility:hidden; }
#fancybox-right:hover span { visibility:hidden; }
/* Change caption color: */
#fancybox-title-float-main { color: #c2bec5 ;}
/* make bakground opaque. */
#fancybox-overlay { opacity: 1 !important; }
/* color background white */
#fancybox-overlay { background : rgba(255, 255, 255, 1) !important ; }
/* nav arrows outside box always on: */
#fancybox-left-ico, #fancybox-left:hover span { left: -40px; }
#fancybox-right-ico, #fancybox-right:hover span { right: -40px; left: auto; }
/* hide fancybox nav arrows: */
#fancybox-left:hover span { visibility:hidden; }
#fancybox-right:hover span { visibility:hidden; }
/* Change caption color: */
#fancybox-title-float-main { color: #c2bec5 ;}