div.button_wrapper {
    float: left;
}

div.box {
    margin-top:50px;
    }
div.box .red_button_wrapper {
    left: 50%;
    margin-left: -50px;
    width: 100px;
    }
div.box .red_button_wrapper input {
    width: 100px;
    #margin-left: 50px;
    _margin-left: 50px;
    }