Here’s what I wound up with for repeaters, I have yet to tackle flexible content fields.
.acf-repeater .acf-row:nth-child(odd) > .acf-row-handle.order,
.acf-repeater .acf-row:nth-child(odd) > .acf-row-handle.remove
{
background: darken(#f4f4f4, 3%);
}