Apply Excel VBA macro to all highlighted cells

Question

Thank you in advance, I am very new to excel VBA. This question may be very elementary, but I haven't found the answer in an extensive search. I originally recorded this macro and tweaked it with stuff I've found online. This macro works if you apply to one cell at a time (or if you drag across multiple rows, will work on the row of the top-left-most cell). Is there a way I can further tweak it to get my macro to apply the changes to the rows of all selected cells so that the user can make changes to rows in bulk?

Range("A" & ActiveCell.Row & ":I" & ActiveCell.Row).Select
With Selection.Interior
    .Pattern = xlSolid
    .PatternColorIndex = xlAutomatic
    .ThemeColor = xlThemeColorDark1
    .TintAndShade = -0.249977111117893
    .PatternTintAndShade = 0
End With
Range("A" & ActiveCell.Row).Select
ActiveCell.FormulaR1C1 = "5"
Range("B" & ActiveCell.Row & ":I" & ActiveCell.Row).Select
With Selection.Font
    .Name = "Calibri"
    .FontStyle = "Regular"
    .Size = 11
    .Strikethrough = True
    .Superscript = False
    .Subscript = False
    .OutlineFont = False
    .Shadow = False
    .TintAndShade = 0
    .ThemeFont = xlThemeFontMinor
End With
Range("B" & ActiveCell.Row).Select

End Sub

Answer 1

Maybe this is what you're after?

'Instead of this:
'Range("A" & ActiveCell.Row & ":I" & ActiveCell.Row).Select
'Do this:
With Application.Intersect(Selection.EntireRow, Range("A:I")).Interior
'The range at hand is now all the cells in the rows of the selection, 
'  but limited to columns A:I.
'Notice we haven't actually modified the selection
    .Pattern = xlSolid
    .PatternColorIndex = xlAutomatic
    .ThemeColor = xlThemeColorDark1
    .TintAndShade = -0.249977111117893
    .PatternTintAndShade = 0
End With
'Range("A" & ActiveCell.Row).FormulaR1C1 = "5"
Application.Intersect(Selection.EntireRow, Range("A:A")).FormulaR1C1 = "5"
'Range("B" & ActiveCell.Row & ":I" & ActiveCell.Row).Select
With Application.Intersect(Selection.EntireRow, Range("B:I")).Font
    .Name = "Calibri"
    .FontStyle = "Regular"
    .Size = 11
    .Strikethrough = True
    .Superscript = False
    .Subscript = False
    .OutlineFont = False
    .Shadow = False
    .TintAndShade = 0
    .ThemeFont = xlThemeFontMinor
End With
Range("B" & ActiveCell.Row).Select

Note: It is not necessary to .SELECT a range and then do something . You can usually just apply something to the range. What you're starting with is typical for macro recorder code, just know there is a cleaner way.