Did you verify this is a real problem by searching

yes

Tell us about the problem

I'd like to be able to do

StackLayout {
  orientation: horizontal;
}

Which platform(s) does your issue occur on?

Both

Please provide the following version numbers that your issue occurs with:

v1.6x (and before)

Please tell us how to recreate the issue in as much detail as possible.

CSS does not appear to be able to set orientation on StackLayout.

Grid: Rows, Columns, row, column, colSpan, rowSpan would also be nice to be able to control in CSS