text: var random = Math.floor(Math.random() * 15);
  
  let programBg = [
      "url('https://i.ibb.co/f8S2FvC/index-back.jpg')",
      "url('https://i.ibb.co/4PW1YcQ/bg2.jpg')",
      "url('https://i.ibb.co/fH8MXV2/bg3.jpg')",
      "url('https://i.ibb.co/1XJd4h0/bg4.jpg')",
      "url('https://i.ibb.co/94BX4sD/bg5.jpg')",
      "url('https://i.ibb.co/WBQyzh5/bg6.jpg')",
      "url('https://i.ibb.co/k2pq32f/Selective-focus-closeup-view-of-cables-plugged-into-a-server-network-panel-with-lights-indicating-ac.jpg')",
      "url('https://i.ibb.co/sKycpDh/bg8.jpg')",
      "url('https://i.ibb.co/t3C1Jy0/bg9.jpg')",
      "url('https://i.ibb.co/SxGL3w6/bg10.jpg')",
      "url('https://i.ibb.co/GsKxcPr/bg11.jpg')",
      "url('https://i.ibb.co/JHhSNJL/bg12.jpg')",
      "url('https://i.ibb.co/YPV4hVj/bg13.jpg')",
      "url('https://i.ibb.co/3vBGVRh/bg14.jpg')",
      "url('https://i.ibb.co/0jS8CQc/bg15.jpg')"];
  
  
  document.getElementById("banner").style.backgroundImage=programBg[random];