.div_error
{
    display: none;
}
.error_box
{
    color: #691715;
    background: #feded9;
    border: 1px solid #fc8675;
    width: 100%;
    margin: 0px auto;
    display: block;
    padding: 10px 15px;
}
.success_box
{
    color: #1b601c;
    background: #b2e7d3;
    border: 1px solid #65cea7;
    width: 100%;
    margin: 10px auto;
    display: block;
    padding: 10px 15px;
}

#backtt 
{
    z-index: 20000;
    position: fixed;
    visibility: visible;
    display: block;
    left: 50%;
    width: 600px;
    margin-left: -300px;
    background-color: green;
    /* margin-top: 166px; */
    /* height: 300px; */
    border: 9px solid #808080;
    border-radius: 8px;
}

       
@media (max-width:480px) 
{
    #backtt  
        {
        width: 100%;
        margin-left: -50%;
        }
}
        
@media (min-width:481px) and (max-width:550px) 
{
    #backtt  
        {
        width: 100%;
        margin-left: -50%;
        }
}

@media (min-width:551px) and (max-width:600px) 
{
    #backtt  
        {
        width: 100%;
        margin-left: -50%;
        }
}

@media (min-width:601px) and (max-width:670px) 
{
    #backtt  
        {
        width: 100%;
        margin-left: -50%;
        }
}

@media (max-width:767px) 
{
    #backtt  
        {
        width: 100%;
        margin-left: -50%;
        }
}

@media (min-width:768px) and (max-width:868px) 
{
    #backtt  
        {
        width: 100%;
        margin-left: -50%;
        }
}