var slide_speed = 1500;
var background_element = "";

function slide_to_top(element) {
    element.animate({top: -600}, slide_speed);
}

function slide_to_right(element) {
    element.animate({left: 0}, slide_speed);
}

function slide_to_bottom(element) {
    element.animate({top: 0}, slide_speed);
}

function slide_to_left(element) {
    element.animate({left: -600}, slide_speed);
}

function randomMovement() {
    element = background_element;
    
    var random_number = Math.random()*100;
    
    if (random_number>=0 && random_number<25) {
        slide_to_top(element);
    }
    
    if (random_number>=25 && random_number<50) {
        slide_to_right(element);
    }
    
    if (random_number>=50 && random_number<75) {
        slide_to_bottom(element);
    }
    
    if (random_number>=75 && random_number<100) {
        slide_to_left(element);
    }
}

$(document).ready(function(){
    background_element = $("#login-background");
    randomMovement();
    setInterval(randomMovement, slide_speed); 
});