Create 2 tables, link them and display a portal on your layout.
Use alternate Row: Unchecked
Appearance/Portal Row/Line/Solid : 0.5 pt (color anything you want, I picked blue)
Select only the Bottom Border for the portal row.
You get this on Filemaker GO 14 on Mac OS
On Filemaker Go 14, the lines disappear
Now uncheck the bottom border and and select top Border
On Filemaker 14 on Mac it will look ok but on filemaker go 14 you will get this strange gradient
Note that everything is fine on filemaker go 13 and on filemaker go 14 if the line height is at least 1 pt.
Now if anyone has a quick fix for this....