css

.toast {
    position: fixed;
    padding: 0 20px;
    font-size: 16px;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    margin: 300px 0 0;
    max-width: 450px;
    text-align: center;
    height: 40px;
    line-height: 40px;
    padding: 0 10px;
    border-radius: 5px;
    background-color: #000;
    filter: alpha(opacity=90);
    -moz-opacity: 0.1;
    background-color: rgba(0,.9);
    color: #fff;
    z-index: 100;
}

js

function toast(txt) {
   $("body").prepend("
" + txt + "
");
   $(".toast").css({"left": ($(window).width() - $(".toast").width())/2});
   setTimeout(function () {
       $(".toast").remove();
   },2000)
}