:root {
  height: 100vh;
  background:
    linear-gradient(#aaa 0 0) 0 0 / 5vw 100%,
    linear-gradient(#aaa 0 0) 100% 0 / 5vw 100%,
    linear-gradient(#aaa 0 0) 50% 50% / 70% 7.5vw,
    linear-gradient(90deg, #666, #eee);
  background-repeat: no-repeat;
}