Simple CSS rotation of background-image. Can be used on element state changes (open, clicked, hover etc.)
.title {
position: relative;
padding-right: 20px;
}
.title:before {
content: "";
position: absolute;
width: 30px;
height: 30px;
top: 0;
right: 0;
background: transparent url(../img/accordion-arrow.svg?x) center center no-repeat;
-webkit-background-size: 1.4rem;
background-size: 1.4rem;
transition: all 500ms;
}
.title.open:before {
-webkit-transform:rotate(90deg);
transform:rotate(90deg);
}