function update_colors () {
  var op = document.getElementsByClassName("opContainer")[0];

  if(op.getElementsByClassName("subject")[0].textContent.indexOf("TRUMP GENERAL") >= 0)
  {
    document.body.style.background = "#1d1f21 url('https://i.imgur.com/QAxc9hZ.jpg') repeat-y fixed center top";
    document.body.style.backgroundSize = "100% auto";

    var posts = document.getElementsByClassName("post");

    for(var i = 0; i< posts.length; i++)
    {
      posts.item(i).style.backgroundColor = "rgba(40,42,46, .7)";
    }
  }
}
update_colors();
window.setInterval(update_colors, 1000);