You can achieve it by adding the following CSS code in the Custom CSS code option of your theme on the below path.

Admin Area -> Appearance -> Theme Settings -> Custom Code -> CSS Code

span.sh-accordion-title {
    font-family: 'Amatic SC', cursive;
    font-size: 1em;
}

.sh-accordion .panel .panel-collapse .panel-body {
    background-color: transparent;
}