How to make numbered dingbats left aligned in a stylesheet

Question

I use cell dingbats and counters in my stylesheet to auto number certain cells. For example, in my private stylesheet I defined the "Outline1" cell style as:

Cell[StyleData["Outline1"],
CellDingbat->Cell[TextData[StyleBox[{CounterBox["Outline1"],"."},Bold]]],
CellMargins->{{50,10},{7,7}},
ReturnCreatesNewCell->True,
StyleKeyMapping->{"Tab"->"Outline2"},
CellGroupingRules->{"SectionGrouping", 40},
ParagraphIndent->0,
LineSpacing->{1,0},
MenuSortingValue->1250,
MenuCommandKey->"2",
CounterIncrements->"Outline1",
CounterAssignments->{{"Outline2",0}},
MenuSortingValue->50,
DefaultReturnCreatedCellStyle->"Outline1"],

This works great. When I create a new "outline1" cell, Mathematica automatically places the counter dingbat to the left of the cell. See pic below.

The only thing I don't like is that the counters are right aligned in front of each cell. You can see this when the counter goes from 9 to 10. I would like to the counters to be left aligned as follows.

How do I alter the stylesheet code given above to make this happen?

Answer 1

It won't adjust itself for 10 digits numbers but a quick fix is to use:

CellDingbat -> Cell[ BoxData[ 
    PaneBox[
       StyleBox[RowBox[{CounterBox["Outline1"],"."}],Bold],
       Alignment->Left,ImageSize->30 (*less than cell margin*)
    ]
]]