#modelos_compatibles .title{
    background-color: #f0f0f0;
    border: 1px solid #ccc;
    color: #222;
    padding: 5px 0px;
    margin-bottom: 5px;
    cursor: pointer;
}

#modelos_compatibles .title.collapsed .arrow-minus{
    display: none;
}

#modelos_compatibles .title:not(.collapsed) .arrow-plus{
    display: none;
}