unexpected behavior with grid-template-rows and 1fr on chrome - css

Question

I'm trying to build a grid with 2 rows inside a flex column. The flex container has a minimum height to fill the window. The first line of the grid should fill the available space, so I was thinking of the fr unit. A simplified version may look like that:
.container {
min-height: 100vh;
display: flex;
flex-direction: column;
}
.grid {
flex-grow: 1;
background-color: red;
padding: 1rem;
grid-gap: 1rem;
display: grid;
grid-template-rows: 1fr auto;
}
.grid > * {
background-color: white;
}
<div class="container">
<h1>some title</h1>
<div class="grid">
<div>line 1</div>
<div>line 2</div>
</div>
</div>
This works perfectly fine with firefox:
But not with chrome:
What am I missing?

Answer 1

The grid container is interpreting the min-height: 100vh on the flex parent differently in Chrome and Firefox.
As you noted, in Firefox everything works as you expect. But in Chrome, the min-height is effectively ignored (even though flex-grow: 1 works on the same element).
If you switch to height: 100vh you'll see the 1fr work in Chrome, as well.
I would have to research more to tell you if this is a bug or not.
Consider nesting the grid inside another grid, as opposed to flex, container.
.container {
display: grid;
min-height: 100vh;
grid-template-rows: min-content 1fr;
}
.grid {
background-color: red;
padding: 1rem;
grid-gap: 1rem;
display: grid;
grid-template-rows: 1fr auto;
}
.grid>* {
background-color: white;
}
<div class="container">
<h1>some title</h1>
<div class="grid">
<div>line 1</div>
<div>line 2</div>
</div>
</div>
jsFiddle demo