Video in home page before login

I’m using this HTML in login_required.welcome_message, looks and is playing fine in desktop version. …

  <div class="overlay"></div>
  <video playsinline= "playsinline" autoplay="autoplay" muted="muted" loop="loop">
    <source src="">


But in the mobile version it looks very large and does not fit the size of the devices.

Can the problem be fixed?

I need help, please.