Video Caption keeps lapping into the Video

Hey Guys so i have been programming for a month now and i am working on a Webpage
So basically there is a Video starting at the very Top of the Webpage and underneath there is a Caption. In the Webbrowser everything is fine and fits.
But if you look at the Page from different Devices with different Screen Sizes the Text beneath the Caption tends to leap upward into the Video. Is there a way to make the Video as an Object which doesnt allow Texts or other onejcts to leap into it?
i Mean there has to be a Way to make Borders between those 2 Objects which work on all Screen Resolutions.
Greetings Mattia

Tell me if you need a Screenshot or a Code