How do I specify row heights in CSS Grid layout

Question

I have a CSS Grid Layout in which I want to make some (middle 3) rows stretch to their maximum size. I'm probably looking for a property similar to what flex-grow: 1 does with Flexbox but I can't seem to find a solution.

I have the following CSS Grid Layout:

.grid {
  display: grid;
  grid-template-columns: 1fr 1.5fr 1fr;
  grid-gap: 10px;
  height: calc(100vh - 10px);
}

.grid .box {
  background-color: grey;
}

.grid .box:first-child,
.grid .box:last-child {
  grid-column-start: 1;
  grid-column-end: -1;
}

/* These rows should 'grow' to the max height available. */
.grid .box:nth-child(n+5):nth-child(-n+7) {
  grid-column-start: 1;
  grid-column-end: -1;
}

<div class="grid">
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
</div>

None of the boxes containing any content even like this:

Answer 1

Apparently, the auto value on the grid-template-rows property does exactly what I was looking for.

.grid {
    display:grid;
    grid-template-columns: 1fr 1.5fr 1fr;
    grid-template-rows: auto auto 1fr 1fr 1fr auto auto;
    grid-gap:10px;
    height: calc(100vh - 10px);
}

Answer 2

take an example where the first row is only 23px high, and the bottom row 100px.

So the middle row should span across the space of the entire page. you do..

​grid-template-rows:23px minmax(100%, 100px) 100px;

this works because 

minmax(100px, 100%) would read 100px first and then allow 100% height

but 

minmax(100%, 100px) will read 100% first and then see that the second is smaller and stretch/shrink to fit as told.