Column style is lost on remaining columns when a sub-range column style is modified

[lievendf]

Steps to Reproduce

1. Set a column style (e.g. Font.Size = 9) across a range of columns (e.g. A:J).
2. Modify a style property (e.g. Font.Bold = true) on a sub-range of those columns (e.g. B:C).
3. Set a value in a cell located in one of the remaining columns of the original range (e.g. cell E1).

Observed Behavior

Cell E1 loses the font size set in step 1 and reverts to the default font size (11pt).

Expected Behavior

Cell E1 retains font size 9 set in step 1.

Minimal Reproducible Code

[TestMethod]
public void MultiColumnStyle_WhenSplitBySubRange_ShouldInheritStyle()
{
    using (var p = new ExcelPackage())
    {
        var ws = p.Workbook.Worksheets.Add("TestSheet");

        // 1. Set font size 9 on columns A to J
        ws.Cells["A:J"].Style.Font.Size = 9;

        // 2. Modify a style property on sub-range B:C
        ws.Cells["B:C"].Style.Font.Bold = true;

        // 3. Populate cell E1 in column E
        ws.Cells["E1"].Value = "Test";

        // Expected: Font size 9
        // Actual:   Font size 11 (Assert.AreEqual failed. Expected:<9>. Actual:<11>.)
        Assert.AreEqual(9f, ws.Cells["E1"].Style.Font.Size, "Cell E1 font size should be 9");
    }
}

[AdrianEPPlus]

I will take a look at this.