I solved it using the maxWidth and maxHeight options on colorbox initialization, as explained on the developer’s website :
jQuery(*selector*).colorbox({maxWidth:'95%', maxHeight:'95%'});
You can also add this snippet to resize the colorbox when resizing the window or changing your mobile device’s orientation :
/* Colorbox resize function */
var resizeTimer;
function resizeColorBox()
{
if (resizeTimer) clearTimeout(resizeTimer);
resizeTimer = setTimeout(function() {
if (jQuery('#cboxOverlay').is(':visible')) {
jQuery.colorbox.load(true);
}
}, 300)
}
// Resize Colorbox when resizing window or changing mobile device orientation
jQuery(window).resize(resizeColorBox);
window.addEventListener("orientationchange", resizeColorBox, false);
Eventually, replace jQuery by $ .