You can hide any element by taking the width of the screen as a parameter. Example, the be-hidden-below-500 class will hide any item below 500px, while be-hidden-above-500 will hide it above 500px.
<!-- 300 to 900 --> <!-- 500 to 900 -->
be-hidden-below-300 be-hidden-above-500
be-hidden-below-400 be-hidden-above-700
be-hidden-below-500 be-hidden-above-900
be-hidden-below-700
be-hidden-below-900
<!-- others -->
be-hidden <!-- set display to none -->
be-ghost <!-- set visibility to hidden -->
The difference between be-hidden and be-ghost is that the former completely disappears the element, while the latter makes it invisible as a ghost.
