.isotope, .isotope .isotope-item
{
    /* change duration value to whatever you like */
    -webkit-transition-duration: 0.8s;
    -moz-transition-duration: 0.8s;
    -ms-transition-duration: 0.8s;
    -o-transition-duration: 0.8s;
    transition-duration: 0.8s;
}

.isotope
{
    -webkit-transition-property: height, width;
    -moz-transition-property: height, width;
    -ms-transition-property: height, width;
    -o-transition-property: height, width;
    transition-property: height, width;
}

.isotope .isotope-item
{
    -webkit-transition-property: -webkit-transform, opacity;
    -moz-transition-property: -moz-transform, opacity;
    -ms-transition-property: -ms-transform, opacity;
    -o-transition-property: top, left, opacity;
    transition-property: transform, opacity;
}

/**** disabling Isotope CSS3 transitions ****/

.isotope.no-transition, .isotope.no-transition .isotope-item, .isotope .isotope-item.no-transition
{
    -webkit-transition-duration: 0s;
    -moz-transition-duration: 0s;
    -ms-transition-duration: 0s;
    -o-transition-duration: 0s;
    transition-duration: 0s;
}