* {
box-sizing: border-box;  
}
h1{
  font-family: Georgia, 'Times New Roman', Times, serif;
  font-size: 50px;
  color: #555;
  text-shadow: 3px 3px 3px white;
  text-align: center;

}
h2{
  font-family: Georgia, 'Times New Roman', Times, serif;
  font-size: 20px;
  color: #555;
  text-shadow: 1px 1px 1px white;
  text-align: center;
  line-height: 30px;
}
.scene {
  position: relative;
  height: 100vh;
  overflow: hidden;
  background: linear-gradient(#a6d8ff, #fff, #fff);
}
.dark .scene {
  background: #222833;
}
.sun{
  position: absolute;
  top: 120px;
  left: 55%;
  transform: translate(-50%);
  width: 100px;
  height: 100px;
  background: #fff;
  border-radius: 50%;
  box-shadow: 0 0 50px #fff;
  cursor: pointer;
  transition: 0.2s;
}

.dark .sun{
  top: 150px;
  left: 45%;
  box-shadow: 0 0 0 #fff;
}

.dark .sun::before{
  content: '';
  position: absolute;
  top: -20px;
  left: 20px;
  width: 100%;
  height: 100%;
  background: #222833;
  border-radius: 50%;
}

.bg {
  position: absolute;
  bottom: 0px;
  width: 100%;
  height: 268px;
  background: url('../images/bg.png');
  animation: animateBg 25s linear infinite;
  background-size: 1500px;
  background-repeat: repeat-x;
}

@keyframes animateBg {
  0%{
    background-position-x: 0px;
  }
    100%{
    background-position-x: -1500px;
  }
}

.car1{
  position: absolute;
  left: -300px;
  bottom: 2px;
  max-width: 200px;
  z-index: 10;
  animation: car1 18s linear infinite;
}
@keyframes car1 {
  0%
  {
    transform: translateX( 0px);
  }
  90%, 100%
  {
    transform: translateX( calc(100vw + 300px));
  }
}

.car2{
  position: absolute;
  right: -400px;
  bottom: 30px;
  max-width: 220px;
  z-index: 5;
  animation: car2 12s linear infinite;
}
@keyframes car2 {
  0%
  {
    transform: translateX( 0px);
  }
  90%, 100%
  {
    transform: translateX( calc(-100vw - 600px));
  }
}