Adding display: flex to an element turns it into a flex container.

This makes it possible to align any children of that element into rows or columns.

You do this by adding the flex-direction property to the parent item and setting it to row or column.

Creating a row will align the children horizontally, and creating a column will align the children vertically.

Other options for flex-direction are row-reverse and column-reverse.

Note: The default value for the flex-direction property is row.

Add the CSS property flex-direction to the #box-container element, and give it a value of row-reverse.

<style> #box-container { display: flex; height: 500px; flex-direction: row-reverse; } #box-1 { background-color: dodgerblue; width: 50%; height: 50%; } #box-2 { background-color: orangered; width: 50%; height: 50%; } </style> <div id="box-container"> <div id="box-1"></div> <div id="box-2"></div> </div>

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FCC---CSS Flexbox: Use the flex-direction Property to Make a Row