How to Fix: Missing visible-** and hidden-** in Bootstrap

Missing visible-* and hidden-* classes in Bootstrap can be fixed by adding them to your CSS or HTML files. The visible-* classes are used to make elements visible, while the hidden-* classes are used to hide them.

To fix this issue, you need to add the missing classes to your HTML elements. For example, if you want to create a row with 4 columns on larger screen sizes, 3 on smaller screens, and 2 on very small screens, you can use the following code:

<div class='row hidden-xs '></div>
<div class='row visible-sm '></div>
<div class='row visible-md '></div>
<div class='row hidden-sm '></div>
<div class='row hidden-xs '></div>

This code creates four rows with different column counts based on the screen size. The `hidden-*` classes are used to hide the rows on smaller screens, while the `visible-*` classes are used to make them visible on larger screens.