#set text(font: "Times New Roman", size: 8pt)
#show table: it => box(fill: luma(230))[
  #table(
    columns: it.columns,
    ..it.children.map(c => {
      if type(c) == content and c.func() == table.header {
        table.header(..c.children.map(h => {
          if type(h) == content and h.func() == table.cell {
            table.cell(strong(h.body))
          } else { strong(h) }
        }))
      } else { c }
    })
  )
]
#table(
  columns: (1fr, 1fr, 1fr),
  table.header([Ш1], table.cell(colspan: 2)[Ш2], []),
  table.header([], [Ш2а], [Ш2б]),
  [1], [2], [3],
)