Re-sizing and re-ordering elements between desktop and mobile layouts - html

Question

I'd like to achieve the following with CSS only (left is mobile layout, right is desktop after breakpoint):
The challenge here obviously is that from a float point of view the element order changes: on mobile the green item is the second, but on desktop it's the first.
Is this possible to achieve with pure CSS? Possibility would be flex-box but I don't have enough experience to recreate this layout.

Answer 1

#container {
display: flex;
flex-direction: column;
flex-wrap: wrap;
height: 400px; /* 1 */
}
.box {
width: 50%;
}
.box1 {
background-color: lightgreen;
height: 400px;
}
.box2 {
background-color: orangered;
height: 200px;
}
.box3 {
background-color: aqua;
height: 200px;
}
#media (max-width: 600px) {
#container { height: auto; } /* 2 */
.box { width: 100%; }
.box2 { order: -1; } /* 3 */
}
/* purely decorative styles */
.box {
border: 1px solid #ccc;
display: flex;
justify-content: center;
align-items: center;
font-size: 1.5em;
}
* { box-sizing: border-box; }
<div id="container">
<div class="box box1"><span>1</span></div>
<div class="box box2"><span>2</span></div>
<div class="box box3"><span>3</span></div>
</div>
jsFiddle
Notes:
Without a fixed height in a column wrap container, flex items don't know where to wrap. So, for your larger screen, define a height which forces the second item to a new column.
Now you're in a mobile layout and wrapping is no longer necessary. The container needs to be twice the height of the desktop layout. Release the height.
Tell the red box to re-position itself first on the list. (The initial order value for flex items is 0.)

Answer 2

Yes you can do this if you can set fixed height on flex-container. You just need to use flex-direction: column and flex-wrap: wrap and then change order with media-queries.
.content {
display: flex;
flex-wrap: wrap;
flex-direction: column;
}
.a {
height: 200px;
background: #00FF02;
}
.b {
height: 100px;
background: red;
}
.c {
height: 100px;
background: blue;
}
#media(min-width:768px) {
.content {
height: 200px;
}
.content > div {
width: 50%;
}
}
#media(max-width:768px) {
.b {
order: -1;
}
}
<div class="content">
<div class="a">A</div>
<div class="b">B</div>
<div class="c">C</div>
</div>

Answer 3

There is also no-flex solution, fiddle (just replace media-query min-width with whatever breakpoint you consider phone width ends):
HTML:
<div class="div1"></div>
<div class="div2"></div>
<div class="div3"></div>
CSS:
div {
width: 50%;
}
.div1 {
background-color: red;
float: right;
height: 200px;
}
.div2 {
background-color: green;
float: left;
height: 400px;
}
.div3 {
background-color: blue;
float: right;
height: 200px;
}
#media (max-width: 500px) {
.div1, .div2, .div3 { width: 100%;}
}