Worksheet worksheet = workbook.ActiveWorksheet;
CellRange wrappedCells = worksheet.GetUsedCellRange(CellPropertyDefinitions.IsWrappedProperty);

for (int i = wrappedCells.FromIndex.RowIndex; i < wrappedCells.ToIndex.RowIndex; i++)
{
    worksheet.Rows[i].AutoFitHeight();
}

public static Color HexStringToColor(string hexColor)
{
    // Remove the # at the front.
    if (hexColor.StartsWith("#"))
    {
        hexColor = hexColor.Substring(1, hexColor.Length - 1);
    }

    byte a = 255;
    byte r = 255;
    byte g = 255;
    byte b = 255;

    int start = 0;

    // Handle ARGB strings (8 characters long).
    if (hexColor.Length == 8)
    {
        start = 2;
    }

    //Handle contracted RGB strings (3 characters long)
    if (hexColor.Length == 3)
    {
        hexColor = string.Format("{0}{0}{1}{1}{2}{2}", hexColor[0], hexColor[1], hexColor[2]);
    }
    else if (hexColor.Length < 6)
    {
        hexColor = hexColor.PadLeft(6, '0');
    }

    // Convert RGB characters to bytes.
    r = byte.Parse(hexColor.Substring(start, 2), NumberStyles.HexNumber);
    g = byte.Parse(hexColor.Substring(start + 2, 2), NumberStyles.HexNumber);
    b = byte.Parse(hexColor.Substring(start + 4, 2), NumberStyles.HexNumber);

    return Color.FromArgb(a, r, g, b);
}