*{
    margin: 0;
    padding: 0;
}

body {
    
    
    background:#333;
}

.form_bg {
    background-color:#eee;
    color:#666;
    padding:20px;
    border-radius:10px;
    position: absolute;
    border:1px solid #fff;
    margin: auto;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    width: 320px;
    height: 290px;
}

.form_bg_cabecera {
    background-color:#eee;
    color:#666;
    padding:0px;
    border-radius:10px;
    position: absolute;
    border:1px solid #fff;
    margin: auto;
    top: -470px;
    right: 0;
    bottom: 0;
    left: 0px;
    width: 520px;
    height: 100px;
}

.form_bg_anterra {
    background-color:#eee;
    color:#666;
    padding:20px;
    border-radius:10px;
    position: absolute;
    border:1px solid #fff;
    margin: auto;
    top: 0px;
    right: 0;
    bottom: 0;
    left: -400px;
    width: 320px;
    height: 250px;
}

.form_bg_combustibles_anterra {
    background-color:#eee;
    color:#666;
    padding:20px;
    border-radius:10px;
    position: absolute;
    border:1px solid #fff;
    margin: auto;
    top: 0px;
    right: 0;
    bottom: 0;
    left: 400px;
    width: 320px;
    height: 250px;
}

.align-center {
    
    text-align:center;
}

#imagen-fondo{
    margin-top: 10px;
}