Here is the CSS code to be added, as it's quite lengthy and doesn't have a specific place to go:
Unfortunately, I'm having trouble figuring out how to apply this to colorBox.
Below is the colorbox.css file provided by them. I've highlighted where I made an adjustment to move the Overlay left by 120px. Now, the challenge is how to re-center #colorbox.
'code'
/*
Colorbox Core Style:
The following CSS is consistent between example themes and should not be altered.
*/
#colorbox, #cboxOverlay, #cboxWrapper{position:absolute; top:0; left:0; z-index:9999; overflow:hidden;}
#cboxWrapper {max-width:none;}
#cboxOverlay{position:fixed; width:100%; height:100%;}
#cboxMiddleLeft, #cboxBottomLeft{clear:left;}
#cboxContent{position:relative;}
#cboxLoadedContent{overflow:auto; -webkit-overflow-scrolling: touch;}
#cboxTitle{margin:0;}
#cboxLoadingOverlay, #cboxLoadingGraphic{position:absolute; top:0; left:0; width:100%; height:100%;}
#cboxPrevious, #cboxNext, #cboxClose, #cboxSlideshow{cursor:pointer;}
.cboxPhoto{float:left; margin:auto; border:0; display:block; max-width:none; -ms-interpolation-mode:bicubic;}
.cboxIframe{width:100%; height:100%; display:block; border:0;}
#colorbox, #cboxContent, #cboxLoadedContent{box-sizing:content-box; -moz-box-sizing:content-box; -webkit-box-sizing:content-box;}
/*
User Style:
Change the following styles to modify the appearance of Colorbox. They are
ordered & tabbed in a way that represents the nesting of the generated HTML.
*/
#cboxOverlay{background:#fff; left:120px; <!-- CHANGED --> }
#colorbox{outline:0;}
#cboxContent{margin-top:32px; overflow:visible; background:#000;}
.cboxIframe{background:#fff;}
#cboxError{padding:50px; border:1px solid #ccc;}
#cboxLoadedContent{background:#000; padding:1px;}
#cboxLoadingGraphic{background:url(images/loading.gif) no-repeat center center;}
#cboxLoadingOverlay{background:#000;}
#cboxTitle{position:absolute; top:-22px; left:0; color:#000;}
#cboxCurrent{position:absolute; top:-22px; right:205px; text-indent:-9999px;}
/* these elements are buttons, and may need to have additional styles reset to avoid unwanted base styles */
#cboxPrevious, #cboxNext, #cboxSlideshow, #cboxClose {border:0; padding:0; margin:0; overflow:visible; text-indent:-9999px; width:20px; height:20px; position:absolute; top:-20px; background:url(images/controls.png) no-repeat 0 0;}
/* avoid outlines on :active (mouseclick), but preserve outlines on :focus (tabbed navigating) */
#cboxPrevious:active, #cboxNext:active, #cboxSlideshow:active, #cboxClose:active {outline:0;}
#cboxPrevious{background-position:0px 0px; right:44px;}
#cboxPrevious:hover{background-position:0px -25px;}
#cboxNext{background-position:-25px 0px; right:22px;}
#cboxNext:hover{background-position:-25px -25px;}
#cboxClose{background-position:-50px 0px; right:0;}
#cboxClose:hover{background-position:-50px -25px;}
.cboxSlideshow_on #cboxPrevious, .cboxSlideshow_off #cboxPrevious{right:66px;}
.cboxSlideshow_on #cboxSlideshow{background-position:-75px -25px; right:44px;}
.cboxSlideshow_on #cboxSlideshow:hover{background-position:-100px -25px;}
.cboxSlideshow_off #cboxSlideshow{background-position:-100px 0px; right:44px;}
.cboxSlideshow_off #cboxSlideshow:hover{background-position:-75px -25px;}
'code'