.icon. By default icons inherit color from their parent, but if desired, can be colored using text utility classes, e.g. .text--a.
.icon--cross
<svg aria-hidden="true" class="icon icon--plus" width="15" height="15" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 15 15">...</svg>
<svg aria-hidden="true" class="icon icon--plus text--a" width="15" height="15" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 15 15">...</svg>