html {
  box-sizing: border-box;
}

*,
*::before,
*::after {
  box-sizing: inherit;
}

body {
  margin: 0;
  background-color: #000000;
}

main {
  margin: 0;
  width: 100%;
  height: 100vh;
  overflow-x: hidden;
  background-image: url(assets/running.gif), url(assets/fances.png), url(assets/houses.png),
    url(assets/buildings.png), url(assets/sky.png);
  background-size: 800px, 350px, 800px, 2500px, cover;
  background-position: center bottom, 0px bottom, 0px bottom, 0px bottom, center center;
  background-repeat: no-repeat, repeat-x, repeat-x, repeat-x, no-repeat;
  opacity: 0;
  transition: background-position 2s linear, opacity 1s cubic-bezier(1, 0, 1, 0.88);
}