body {
    margin: 0;
  }
  main {
    display: flex;
    flex-wrap: wrap;
    background-color: lemonchiffon;
  }
  main div {
    height: 50vh;
    width: 25%;
  }
  .rect {
    width: 100%;
    background-color: #fff0f5;
  }
  .tri {
    box-sizing: border-box;
    border-right: 25vw solid lightcyan;
    border-top: 25vw solid transparent;
    border-bottom: 25vw solid transparent;
  }