*{
    margin:0;
    padding:0;
    box-sizing: border-box;
}

body{
    font-family: 'Courier New', Courier, monospace;
    text-align: center;
}
#board{
    background-image: url(flappybirdbg.png);

}
body {
  animation: skyGlow 8s ease-in-out infinite alternate;
}

@keyframes skyGlow {
  from { background-position: 0% 0%; filter: brightness(1); }
  to { background-position: 0% 100%; filter: brightness(1.07); }
}
.promo{
  margin: 18px auto 0;
  width: 100%;
  max-width: 980px;
  display: flex;
  justify-content: flex-start;
}
.promo img{
  width: min(100%, 720px);
  height: auto;
  border-radius: 12px;
  image-rendering: pixelated;
  box-shadow: 0 10px 30px rgba(0,0,0,.35);
  border: 1px solid rgba(255,255,255,.08);
}
@media (max-width: 640px){
  .promo{ justify-content: center; }
  .promo img{ width: 100%; }
}