How can I create a 3-column layout using HTML and CSS without modifying the original HTML structure?

HTML/CSS 3-Column Layout

This article addresses how to arrange HTML columns without altering the original HTML structure. Specifically, the focus is on transforming a layout from:

<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>

into a grid-like structure as shown below:

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

CSS Styling

To achieve this transformation without modifying the HTML, CSS can be employed. As demonstrated in the example below, simply setting the float and width properties for the column-left, column-right, and column-center classes can align the elements horizontally:

.column-left {
  float: left;
  width: 33.333%;
}

.column-right {
  float: right;
  width: 33.333%;
}

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

Extended Grid System

This approach can be extended to accommodate more columns. For instance, a five-column layout can be created with the following CSS rules:

.column {
  float: left;
  position: relative;
  width: 20%;
}

.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%;
}

By utilizing these offset and inset classes, columns can be positioned and aligned as needed.

Example Code Snippets

<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>

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