When a user clicks on a link in your in5-exported content that uses either a text anchor or a bookmark anchor as the Destination to go to specific text in your document, in5 adds a yellow box at the beginning of that text to highlight the location in order to help the user.

If you would prefer to not have the yellow highlight, then add the following code to the CSS portion of the Resources section of the Export HTML5 with in5 dialog:

.in5-highlight {

With InDesign and in5, you can not only create content to help guide your users but also customize your output to match your desired aesthetic.