<html>
<head>
    <style>
        #outside {
           outline: 1px dashed red;
           width: 600px;
        }
        #containingBlock { 
           display: inline;
           position: relative;
           background-color: green;
           margin: 10px;
           padding: 0 10px;
           border: 1px solid grey;
           border-left: 20px solid blue;
           border-right: 20px solid orange;
        }
        #test {
           position: absolute;
           top: 0;
           left: 0;
           width: 100%;
           height: 100%;
           outline: 5px solid black;
        }
    </style>
</head>
<body>
    <p>The black outline box should stretch from the left <span style="color: blue;">blue</span> border, to the right <span style="color: orange;">orange</span> border.</p>
    <div id="outside">
        ILorem ipsum dolor sit amet,
        <span id="containingBlock">
            con a pariatur.
            <div id="test"></div>
            duis aute
        </span>
        irure dolor in reprehenderit.
    </div>
</body>
</html>