I don't believe there is an inherent "text box" functionality in ePub - there
might be using JS.
You could just use the ______ (underscore), or an inline image of a box
, or really fancy:
Code:
.box {border:1px solid black; letter-spacing:8em; line-height:1.5}
<span class="box"> </span>
<p>Lorem ipsum dolor sit amet, <span class="box"> </span> consectetur adipiscing elit. Nullam nec leo sapien. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aliquam erat volutpat.</p>