prima di provare, fatti un backup del file!!!

codice:
inFile = "dept_200.html"
outFile =  = "dept_200.tmp"

Open inFile For Input As #1 
Open outFile For Output As #2 

linea = "<link rel='stylesheet' type='text/css' href='style.css' />" 
Print #2, linea

Do While Not EOF(1) 
Line Input #1, linea 
MsgBox Linea
Print #2, linea
Loop 

Close #1 
Close #2

Kill inFile
Name outFile As inFile