Is there a notion of zorder?

Questions
1

I have the following:

#let _shadecolor = "#eee"
#let _boxborder = 1pt
#let _gridlines = 0.1pt
#let _insetvalue = 4pt

#grid(columns:(1fr,), stroke:_boxborder,
  grid(columns:(1fr), stroke:none,
    grid(columns: (1fr), fill: rgb(_shadecolor),stroke: _gridlines,inset:3pt,align:(center),
      [Header]
    ),
    grid(columns:(3fr,5fr,2fr,), inset: _insetvalue, 
      [data1],
      [data2],
      [data3],
    ),
    grid(columns:(2fr,)*6,inset: _insetvalue,
      [data1],
      [data2],
      [data3],
    ),
  ),
)

The Header has a fill which interferes with the box border (the left and right vertical lines are thinner around the header).
Is there a way to make the box border be on top of all the children?

2

You might be able to use a block with clip: true.

3

Found a workaround by adding an inset of half the box border:

...
#grid(columns:(1fr,), stroke:_boxborder, inset: _boxborder/2,
...