#row-gap (grid-row-gap)

/* <length> values */
row-gap: 20px;
grid-row-gap: 20px;
row-gap: 1em;
grid-row-gap: 1em;

/* <percentage> value */
row-gap: 10%;
grid-row-gap: 10%;

/* calc() values */
row-gap: calc(10% + 20px);
grid-row-gap: calc(10% + 20px);