<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="style.css"/>
</head>
<body>

    <div class="container">
        <!-- 💛 build one more class (box-one)-->
        <div class="box box-one">A</div>
        <div class="box">B</div>
        <div class="box">C</div>
    </div>


</body>
</html>
body {
    margin: 10px;
}

.container{
    border: 3px solid lightgray;
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items:center;
    height: 90vh;
}

.box{

    width:5rem;
    height:5rem;
    background-color: gold;
    margin: 1rem;

}

/* 💛 */
.box-one{
    align-self: flex-start;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.