Flexbox: Layout with rowspan - css

Question

My HTML is similar to the following example
<div id="wrapper">
<div id="a">a</div>
<div id="b">b</div>
<div id="c">c</div>
<div id="d">d</div>
</div>
On desktop I'd like the divs to display next to each other which is of course trivial.
On mobile I'd like have table-like layout with similar to the following
b, c and d have flexible height so a would have to adjust to that.
Is that possible to do without wrapping b,c and d in a separate div?

Answer 1

Yes, you can do this entirely with flexbox...of course you're going to need to decide on a width for the first div at smaller viewport sizes but I assume that you have that in mind already ready for the required media query.
#wrapper {
height: 100vh;
width: 90vw;
border: 1px solid grey;
display: flex;
flex-direction: column;
flex-wrap: wrap;
margin: 10px auto;
}
#wrapper div {
flex: 1 0 auto;
border: 1px solid white;
background: lightblue;
text-align: center;
}
#a {
flex-grow: 1;
height: 100%;
flex-basis: 50%;
}
#media screen and (min-width: 640px) {
#a {
height: auto;
flex-grow: none;
flex-basis: auto;
}
}
<div id="wrapper">
<div id="a">a</div>
<div id="b">b</div>
<div id="c">c</div>
<div id="d">d</div>
</div>
Codepen Demo

Answer 2

Use only flexbox when it's needed: on desktop version:
* { box-sizing: border-box; }
body { margin: 0; }
#a { background: tomato; }
#b { background: forestgreen; }
#c { background: dodgerblue; }
#d { background: orange; }
#wrapper {
overflow: hidden;
position: relative;
}
#wrapper > div {
float: left;
width: 50%;
margin-left: 50%;
padding: 5px;
}
#wrapper > #a {
position: absolute;
height: 100%;
margin-left: 0;
}
#media all and (min-width: 768px) {
#wrapper {
display: flex;
}
#wrapper > div {
margin-left: 0;
}
#wrapper > #a {
position: relative;
height: auto;
}
<div id="wrapper">
<div id="a">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed non risus. Suspendisse lectus tortor, dignissim sit amet, adipiscing nec, ultricies sed, dolor. Cras elementum ultrices diam. Maecenas ligula massa, varius a, semper congue, euismod non, mi. Proin porttitor, orci nec nonummy molestie, enim est eleifend mi, non fermentum diam nisl.</div>
<div id="b">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed non risus. Suspendisse lectus tortor, dignissim sit amet, adipiscing nec, ultricies sed, dolor. Cras elementum ultrices diam. Maecenas ligula massa, varius a, semper congue, euismod non, mi. Proin porttitor, orci nec nonummy molestie, enim est eleifend mi, non fermentum diam nisl sit amet erat. Duis semper. Duis arcu massa, scelerisque vitae, consequat in, pretium a, enim. Pellentesque congue. Ut in risus volutpat libero pharetra tempor. Cras vestibulum bibendum augue. Praesent egestas leo in pede. Praesent blandit odio eu enim. Pellentesque sed dui ut augue blandit sodales. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Aliquam nibh.</div>
<div id="c">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed non risus. Suspendisse lectus tortor, dignissim sit amet, adipiscing nec, ultricies sed, dolor. Cras elementum ultrices diam. Maecenas ligula massa, varius.</div>
<div id="d">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed non risus. Suspendisse lectus tortor, dignissim sit amet, adipiscing nec, ultricies sed, dolor. Cras elementum ultrices diam. Maecenas ligula massa, varius a, semper congue, euismod non, mi. Proin porttitor, orci nec nonummy molestie, enim est eleifend mi, non fermentum diam nisl sit amet erat. Duis semper.</div>
</div>