SOURCE

<div class="container">
    <div class="child child1" style="order: 1">1</div>
    <div class="child" style="order: 2">2</div>
    <div class="child" style="order: 3">2</div>
    <div class="child" style="order: 4">2</div>
    <div class="child" style="order: 5">2</div>
    <div class="child" style="order: 6">2</div>
    <div class="child" style="order: 7">2</div>
</div>

.container {
    width: 200px;
}
.child {
    border: 1px solid green;
    margin: 10px;
    height: 40px;
}