HTML 構造を変更せずに、CSS のみを使用して 3 列の水平レイアウトを作成するにはどうすればよいですか?

<div class="container">
   <div class="column-center">Column center</div>
   <div class="column-left">Column left</div>
   <div class="column-right">Column right</div>
</div>

----------------------------------------------------
|              |                   |               |
| Column left  |   Column center   | Column right  |
|              |                   |               |
----------------------------------------------------

.column-left{ float: left; width: 33.333%; }
.column-right{ float: right; width: 33.333%; }
.column-center{ display: inline-block; width: 33.333%; }

.column {
    float: left;
    position: relative;
    width: 20%;
    
    /*for demo purposes only */
    background: #f2f2f2;
    border: 1px solid #e6e6e6;
    box-sizing: border-box;
}

.column-offset-1 {
    left: 20%;
}
.column-offset-2 {
    left: 40%;
}
.column-offset-3 {
    left: 60%;
}
.column-offset-4 {
    left: 80%;
}

.column-inset-1 {
    left: -20%;
}
.column-inset-2 {
    left: -40%;
}
.column-inset-3 {
    left: -60%;
}
.column-inset-4 {
    left: -80%;
}

<div class="container">
   <div class="column column-one column-offset-2">Column one</div>
   <div class="column column-two column-inset-1">Column two</div>
   <div class="column column-three column-offset-1">Column three</div>
   <div class="column column-four column-inset-2">Column four</div>
   <div class="column column-five">Column five</div>
</div>