CSS flex, how to display one item on first line and two on the next line

Question

This is a pretty simple question, I guess, but I can't get 3 items in the flex container to display in 2 rows, one in the first row and the other 2 in the second row. This is the CSS for the flex container. It displays the 3 items on a single line, obviously :)

div.intro_container {
  width: 100%;
  display: flex;
  flex-direction: row;
  flex-wrap: nowrap;
}

If flex-wrap is set to wrap, then the 3 items are displayed in a column. I thought the wrap setting was needed to display container items on several lines. I've tried this CSS for the first container item, intending to have it occupy the whole of the first row, but it didn't work

div.intro_item_1 {
  flex-grow: 3;
}

I've followed the instructions in "CSS-Tricks" but I'm really not sure which combination of commands to use. Any help would be very welcome as I'm puzzled by this.

Answer 1

You can do something like this:

.flex {
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
}

.flex>div {
  flex: 1 0 50%;
}

.flex>div:first-child {
  flex: 0 1 100%;
}

<div class="flex">
  <div>Hi</div>
  <div>Hello</div>
  <div>Hello 2</div>
</div>

Here is a demo: http://jsfiddle.net/73574emn/1/

This model relies on the line-wrap after one "row" is full. Since we set the first item's flex-basis to be 100% it fills the first row completely. Special attention on the flex-wrap: wrap;