html,
body{
    height:100%;
}

.main-content{
    padding-top:70px; /* altezza navbar */
}

.accordion-button::after{
    background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='%23f0a031' viewBox='0 0 16 16'%3E%3Cpath fill-rule='evenodd' d='M1.646 4.646a.5.5 0 0 1 .708 0L8 10.293l5.646-5.647a.5.5 0 0 1 .708.708l-6 6a.5.5 0 0 1-.708 0l-6-6a.5.5 0 0 1 0-.708z'/%3E%3C/svg%3E");
}

.accordion-button:not(.collapsed)::after{
    background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='%23f0a031' viewBox='0 0 16 16'%3E%3Cpath fill-rule='evenodd' d='M1.646 4.646a.5.5 0 0 1 .708 0L8 10.293l5.646-5.647a.5.5 0 0 1 .708.708l-6 6a.5.5 0 0 1-.708 0l-6-6a.5.5 0 0 1 0-.708z'/%3E%3C/svg%3E");
}