What to do if your editor does not reply and there is no one else to contact? The situation is like this. I made a new submission to a journal via their website; I am under the impression that an author would automatically receive a copy of the generated PDF file for review and the acknowledgement of receipt, just like many journals more or less do. However, after one business day, there was still nothing about this matter that came into my inbox (used in a generic sense, including spam). I thus wrote to the editor in chief regarding this matter. The editor has not yet replied for a day (which is unusual according to the editor's known pattern in dealing with submissions). There is no email for the editorial assistant that I can find on their website, even if the position exists. 

Now the question is how then a safe next move would be like. I cannot just wait indefinitely; potential possibilities are fading. But it also seems that it is difficult to make the intention to ``set a deadline for response" sound innocuous. I am asking if there is a relatively common practice our there or an all-considering well-rounded strategy regarding this matter that could serve as a signal for the editor to know my intention without tearing anyone's face.
See if you can download the PDF from the journal submission website. The editorial management systems I'm familiar with will take the author-submitted source files and generate something, which can then be downloaded by everyone (including the author). In fact, some editorial management systems will generate a preview for the author to approve before the submission is formally registered. If you've not received a "submission received" email, there's a chance that it hasn't been submitted right. 

Otherwise, it has only been one day. One day really isn't a lot of time (especially since it's currently a weekend). Even if someone usually responds in one day, he could be ill or on leave. I would wait a bit longer - maybe 2-3 more days.

If the manuscript was submitted correctly and there's still no response from the editor-in-chief after 2-3 more days, I'd email the publisher. You mentioned you can't find an email for the journal's editorial assistant, but you might still be able to find a "contact us" link on the publisher's website, and they'll be able to redirect you to the right person.