wp-calypso/client/my-sites/themes/atomic-transfer-dialog.scss

.themes__atomic-transfer-dialog-notice {
	.gridicons-sync > use:first-child,
	.gridicons-sync > g:first-child {
		animation: spinning-sync-icon linear 2s infinite;
		transform-origin: center;
	}
}

@keyframes spinning-sync-icon {
	from {
		transform: rotate(0deg);
	}
	to {
		transform: rotate(360deg);
	}
}