How to make rows in a grid stack without grid-template-row? - position

Question

I'm trying to make .item-1 and .item-2 stack nicely on top of each other in a grid, just like in this snippet:
.grid {
display: grid;
gap: 10px;
grid-template-columns: repeat(6, 1fr);
grid-template-rows: auto 1fr;
}
.item {
padding: 10px;
border: 1px solid black;
}
.item-1 {
grid-column: 1 / 3;
}
.item-2 {
grid-column: 1 / 3;
}
.item-3 {
grid-column: 3 / 7;
grid-row: 1 / 3;
padding: 80px 20px;
}
<div class="grid">
<div class="item item-1">
item-1
</div>
<div class="item item-2">
item-2
</div>
<div class="item item-3">
item-3
</div>
</div>
This is a simplified example, and the implementation I'm stuck on has more rows of items in different places.
For example: large item first, or no large item at all.
Which is why grid-template-rows seems to be off the table, and I cannot find a way to stack them nicely without.
I've tried many different things, from grid-auto-rows to the various grid-* and align-*, to height and margins set to auto and fit-content, without success.
Here's the same snippet without grid-template-rows, where you can see the default behavior of .item-1 and .item-2 being separated / getting the same height:
.grid {
display: grid;
gap: 10px;
grid-template-columns: repeat(6, 1fr);
}
.item {
padding: 10px;
border: 1px solid black;
}
.item-1 {
grid-column: 1 / 3;
}
.item-2 {
grid-column: 1 / 3;
}
.item-3 {
grid-column: 3 / 7;
grid-row: 1 / 3;
padding: 80px 20px;
}
<div class="grid">
<div class="item item-1">
item-1
</div>
<div class="item item-2">
item-2
</div>
<div class="item item-3">
item-3
</div>
</div>
Here's an image of the snippets, showing the desired layout:

Answer 1

Try this
.grid {
display: grid;
grid-template-columns: 1fr 2fr;
gap: 10px;
}
.item {
border: 1px solid #000;
padding: 10px;
}
.box1 {
display: flex;
flex-direction: column;
gap: 10px;
}
.item2 {
flex: 1;
}
.item3 {
padding: 80px 20px;
}
<div class="grid" >
<div class="box1">
<div class="item" >item 1</div>
<div class="item item2" >item 2</div>
</div>
<div class="item item3" >item 3</div>
</div>

Answer 2

.grid {
display: grid;
grid-template-columns: 1fr 2fr;
gap: 10px;
}
.item {
border: 1px solid #000;
padding: 10px;
}
.box1 {
display: flex;
flex-direction: column;
gap: 10px;
}
.item1 {
flex: 1;
}
.item2 {
flex: 1;
}
.item3 {
padding: 80px 20px;
}
<div class="grid" >
<div class="box1">
<div class="item item1" >item 1</div>
<div class="item item2" >item 2</div>
</div>
<div class="item item3" >item 3</div>
</div>