in our CMS we have a header folder inside the template directory. If you name the file form.tpl, it should insert it itself only when form.tpl is called (we process this using the smarty template mechanism). I think this is a good practice.
Another solution would be to use classes or identifiers on your body. <body id="suscribeForm"> and use them as a link in your css. (the problem is that CSS is loaded even if you donβt use it, but on the other hand it is already cashed if the user goes to another page).
You can also link different CSS files to the main CSS, but this is not a good practice, because your browser will wait for mains.css to load, and then download the related files.
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