Yes, the content is deliberately hidden as the viewport get's smaller to avoid clutter on mobile device. But if you want it to show Use this code...
.fp-slideshow-simplecontent .g-simplecontent-layout-header .g-simplecontent-item-leading-content {
display: block;
}
To create a custom CSS compatible with Gantry 5 please read this
http://docs.gantry.org/gantry5/tutorials/adding-a-custom-style-sheet
.
Remember to recompile CSS from base outline too.
Regards, Mark.