You can try the Outline
style for the Row.
You need to add it using attributes.add()
method.
Remove border setting for the Table1
See Complete code as below:
Dim table1 As New HtmlTable
'table1.Border = "1"
'table1.BorderColor = "Blue"
For j As Integer = 0 To 2
Dim row As New HtmlTableRow()
Dim cell1 As New HtmlTableCell()
Dim cell2 As New HtmlTableCell()
Dim rbl As New RadioButtonList()
row.Attributes.Add("style", "outline: thin solid blue;")
For RowIndex As Integer = 0 To 2
rbl.ID = RowIndex
rbl.Items.Add("Hi")
Dim lbl1 As New Label()
lbl1.ID = "Hi" + RowIndex.ToString
lbl1.Text = "hello"
lbl1.Height = "25"
cell2.Controls.Add(lbl1)
'Add This
cell2.Controls.Add(New LiteralControl("<br />"))
Next
cell1.Controls.Add(rbl)
row.Cells.Add(cell1)
row.Cells.Add(cell2)
table1.Rows.Add(row)
Next
PlaceHolder1.Controls.Add(table1)