Wouldn't the simple (and sane) thing be to output the HTML after you have processed your input and given values to variables? Also, you may want to consider using HTML::Template or similar to separate your Perl code from your HTML/CSS/JS.

You could also consider making this a dynamic page rather than writing a static HTML file each time the script runs. Though this may be out of scope for this coursework.

Update:

I don't know if this is your entire code, but I'd suggest adding use strict; use warnings; (see Use strict and warnings or search for more), ensure you're opening files properly by checking for errors, for example:

open (LOG, '<', 'IN-access.log') or die "cannot open < IN-access.log: 
+$!";
[download]

Such things help prevent facepalm.