#game {
  position: relative;
  width: 100%;
  height: 600px;
  background-image: url("../images/sky.png");
}

.bird {
  position: absolute;
  background-image: url("../images/birds.png");
  width: 30px;
  height: 30px;
  left: 50%;
  transform: translateX(-50%);
  top: 260px;
  transition: top 0.3s linear;
}

.start {
  top: 320px;
  position: absolute;
  font-size: 30px;
  font-weight: bold;
  left: 50%;
  transform: translateX(-50%);
  cursor: pointer;
  transition: all 0.3s linear;
}
.start.start-white {
  color: #fff;
  font-size: 24px;
}
.start.start-blue {
  color: #09f;
  font-size: 36px;
}

.score {
  position: absolute;
  font-size: 30px;
  color: azure;
  left: 50%;
  transform: translateX(-50%);
  display: none;
}

.mask {
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  left: 0;
  background-color: black;
  opacity: 0.5;
  display: none;
  z-index: 2;
}
.end {
  position: absolute;
  top: 60px;
  left: 50%;
  transform: translateX(-50%);
  display: none;
  text-align: center;
  z-index: 3;
}

.end .over {
  font-size: 35px;
  color: red;
  font-weight: bolder;
}

.end .result,
.end .final-score {
  margin-top: 20px;
  color: #ff0;
  font-size: 20px;
  font-weight: bold;
}

.end .rank-list {
  margin-top: 20px;
  color: #09f;
  text-align: left;
}

.end .rank-item {
  height: 30px;
  line-height: 30px;
  margin-bottom: 10px;
  padding: 0 10px;
  font-size: 13px;
}

.end .rank-degree {
  display: inline-block;
  width: 14px;
  height: 14px;
  line-height: 14px;
  margin-right: 10px;
  text-align: center;
  color: #fff;
  background-color: #8eb9f5;
  font-size: 12px;
}

.end .rank-degree.first {
  background-color: #f54545;
}

.end .rank-degree.second {
  background-color: #ff8547;
}

.end .rank-degree.third {
  background-color: #ffac38;
}

.end .rank-score {
  width: 30px;
  display: inline-block;
}

.restart {
  top: 270px;
  position: absolute;
  font-weight: lighter;
  left: 50%;
  transform: translateX(-65%);
  cursor: pointer;
  color: #09f;
  font-size: 36px;
  text-align: center;
}

.pipe {
  position: absolute;
  width: 52px;
  height: 150px;
  background-color: red;
  z-index: 1;
}

.pipe.pipe-up {
  top: 0;
  background-image: url("../images/pipe2.png");
  background-position-y: bottom;
}

.pipe.pipe-down {
  bottom: 0;
  background-image: url("../images/pipe1.png");
}