html, body {
  height: 96vh;
  width: 96vw;
  margin: auto;
}
body{
  background-color: skyblue;
  background-repeat: no-repeat;
  background-position: center center; 
  background-image: url("../pic/logo300.png");
  background-attachment: fixed;
  background-clip: content-box;
  color: black;
  display: flex;
  flex-direction: column; 
  justify-content:center;
}