<title>Ambiguous line width</title> <div style="background: yellow; width: 10em; height: 10em; line-height: 1; font-family: sans-serif;"> <div style="float: left; height: 2em; width: 1em; background: blue"></div> <div style="float: left; clear: left; height: 2em; width: 5em; background: aqua"></div> <!-- small <span style="font-size: 3em">big</span> --> <span style="display:inline-block; height: 1em; width: 4em; background: maroon; vertical-align: bottom"></span> <span style="display:inline-block; height: 3em; width: 4em; background: maroon; vertical-align: bottom"></span> </div>