$(document).ready(function() {
    $("#gallery li a img").addClass("inactive");
    $("#gallery li.active a img").removeClass("inactive");
    $("#gallery li a img.inactive").css("opacity", "0.3");
    }
);
$(function() {
    // OPACITY OF BUTTON SET TO 50%

    // ON MOUSE OVER
    $("#gallery li a img.inactive").hover(function() {

        // SET OPACITY TO 100%
        $(this).stop().animate({
            opacity: 1.0
        }, "slow");
    },

    // ON MOUSE OUT
    function() {

    // SET OPACITY BACK TO 50%
        $(this).stop().animate({
            opacity: 0.3
        }, "slow");

    });
});