Please add the following code to js file in your THEME (function ($, Drupal, window, document, undefined) { //Configure colorbox call back to resize with custom dimensions $.colorbox.settings.onLoad = function() { colorboxResize(); } //Customize colorbox dimensions var colorboxResize = function(resize) { var width = "90%"; var height = "90%"; if($(window).width() > 960) { width = "860" } if($(window).height() > 700) { height = "630" } $.colorbox.settings.height = height; $.colorbox.settings.width = width; //if window is resized while lightbox open if(resize) { $.colorbox.resize({ 'height': height, 'width': width }); } } //In case of window being resized $(window).resize(function() { colorboxResize(true); }); })(jQuery, Drupal, this, this.document);