How can I make my flexbox layout take 100% vertical space?

set the wrapper to height 100%

.vwrapper {
  display: flex;
  flex-direction: column;

  flex-wrap: nowrap;
  justify-content: flex-start;
  align-items: stretch;
  align-content: stretch;

  height: 100%;
}

and set the 3rd row to flex-grow

#row3 {
   background-color: green;
   flex: 1 1 auto;
   display: flex;
}

demo


You should set height of html, body, .wrapper to 100% (in order to inherit full height) and then just set a flex value greater than 1 to .row3 and not on the others.

.wrapper, html, body {
    height: 100%;
    margin: 0;
}
.wrapper {
    display: flex;
    flex-direction: column;
}
#row1 {
    background-color: red;
}
#row2 {
    background-color: blue;
}
#row3 {
    background-color: green;
    flex:2;
    display: flex;
}
#col1 {
    background-color: yellow;
    flex: 0 0 240px;
    min-height: 100%;/* chrome needed it a question time , not anymore */
}
#col2 {
    background-color: orange;
    flex: 1 1;
    min-height: 100%;/* chrome needed it a question time , not anymore */
}
#col3 {
    background-color: purple;
    flex: 0 0 240px;
    min-height: 100%;/* chrome needed it a question time , not anymore */
}
<div class="wrapper">
    <div id="row1">this is the header</div>
    <div id="row2">this is the second line</div>
    <div id="row3">
        <div id="col1">col1</div>
        <div id="col2">col2</div>
        <div id="col3">col3</div>
    </div>
</div>

DEMO


EDIT, as mention by @Basj , the code can be shorten . We can also nowdays use grid widely implemented : Below an example with grid for the visitors :

body {height: 100vh;display: grid;grid-template-rows:auto auto 1fr;margin: 0;background-color: orange;grid-template-columns:240px 1fr 240px;}
[id^=row]{grid-column:1/-1}
#row1 {background-color: red;}
#row2 {background-color: blue;}
#row3 {background-color: green;}
#col1 {background-color: yellow;}
#col3 {background-color: purple;}
<div id="row1">this is the header</div>
<div id="row2">this is the second line</div>
<div id="col1">col1</div>
<div id="col2">col2</div>
<div id="col3">col3</div>

Tags:

Html

Css

Flexbox