title: Remove Background HTML5-Video/WEBVTT subtitle on iOS iPhone/iPad
body: <p>I have a HTML5 video with a track-element for subtitles in webvtt-format.
  How can I remove the black background behind the subtitles on iOS/iPhone/iPad?
  In the browsers on a PC I can remove it with CSS ::cue{background: transparent;} </p>
  
  <p>Thanks for help</p>