How to change order of divs on smaller screens?

Question

I need to reorder the divs when screen size is less than 480px.

I don\'t want to use position: absolute because the height of the green area may vary du

Answer 1

With CSS Flexbox you can control the visual order of elements with the order property and the x/y direction of the divs with the flex-direction property.

Here are a few simple adjustments to your code that make your layout work:

CSS

.container {
     display: flex; /* NEW */
    /* width: 100%; */
    /* display: inline-block; */
    /* box-sizing: border-box; */
}

@media screen and (max-width: 480px) {
    .full_half {  width: 100%; }
    .text      {  padding: 0 0 !important; }
    .container { flex-direction: column; }         /* NEW */
    .container:nth-child(2) > .pic { order: -1; }  /* NEW */
}

Now when the screen size is less than 480px the divs are stacked in a single column and the order is red, green, red, green, red, green.

*,
html,
body {
  margin: 0;
  padding: 0;
}
.container {
  display: flex;
}
.full_half {
  display: inline-block;
  width: 50%;
  background-color: green;
  float: left;
  min-height: 100px;
}
.pic {
  background-color: red;
  height: 100px;
}
.text {
  box-sizing: border-box;
  padding: 20px 120px;
}
@media screen and (max-width: 480px) {
  .full_half {
    width: 100%;
  }
  .text {
    padding: 0 0 !important;
  }
  .container {
    flex-direction: column;
  }
  .container:nth-child(2) > .pic {
    order: -1;
  }
}

<div class="container">
  <div class="full_half pic"></div>
  <div class="full_half text">test</div>
</div>
<div class="container">
  <div class="full_half text">test</div>
  <div class="full_half pic"></div>
</div>
<div class="container">
  <div class="full_half pic"></div>
  <div class="full_half text">
    dfdfdfdfdfdffdfdfdfdfdfdfdfdfdfdf
    <br />dfdfdfdfdfdffdfdfdfdfdfdfdfdfdfdf
    <br />dfdfdfdfdfdffdfdfdfdfdfdfdfdfdfdf
    <br />
  </div>
</div>

revised fiddle

In the example above, child elements of the flex container (.container) are aligned in a row, which is the default layout of a flexbox (flex-direction: row).

Each child element is order: 0 by default. By giving the div with the .pic class in the second .container an order value of -1, it gets positioned before its sibling (div with .text with a value of 0). We could also have given the first sibling a value of 1, thus moving it after div with .pic. Learn more about the order property.

By changing the value of flex-direction from its default (row) to column, the divs stack up in a single column. Learn more about the flex-direction property.

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Browser support: Flexbox is supported by all major browsers, except IE < 10. Some recent browser versions, such as Safari 8 and IE10, require vendor prefixes. For a quick way to add all the prefixes you need, use Autoprefixer. More details in this answer.