.accordion:after {
    content: "";
    background-image: url(/res/arrows/arrow_down_black.png);
    background-position: 0;
    background-repeat: no-repeat;
    display: inline-block;
    margin-left: 10px;
    transition: background-image 0.2s;
    -webkit-transition: background-image 0.2s;
    width: 15px;
    height: 15px;
  }

.accordion.active:after {
    background-image: url(/res/arrows/arrow_up_bluep.png);
}

.panel {
    overflow: hidden;
    max-height: 0;
    transition: max-height 0.2s ease-out;
    -webkit-transition: max-height 0.2s ease-out;
}