body {
  height: 100%;
  width: 100%;
  margin: 0;
}

.container {
  position: relative;
  height: 400px;
  margin: 0 auto;
  border: 3px solid #52cf18;
  background-color: #328087;
  margin-left: 4px;
  overflow: hidden;
}

#bird {
  position: absolute;
  background-image: url('bird.png');
  background-color: #58c616;
  height: 40px;
  width: 60px;
  background-size: contain;
  background-repeat: no-repeat;
  top: 15%;
  left: 30%;
}

.pole {
  position: absolute;
  right: -50px;
  width: 50px;
  height: 100px;
  background-color: #554ca4;
}

#pole_1 {
  top: 0;
}

#pole_2 {
  bottom: 0;
}

#restart_btn {
  position: absolute;
  width: 100%;
  height: 60px;
  background: steelblue;
  font-size: 20px;
  top: 0;
  display: none;
}