a{
    text-decoration: none;
    color: white;

}
footer{
  color: lightyellow;
  font-size: 1.3em;
}
 body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
  padding: 0;
  text-align: center;
  
  color: white;
  font-size: 1.3em;
}
 


a:hover{
            transition: 0.5s;
            color: gray;
        }
        @media (max-width:640px) {

    body {
        background-size: cover;
        background-position: top;
        background-position: center;
        margin: 0px;
        padding: 50px 5%;
        background-image: url(science-fiction-1674554_640.jpg);
       height: 90vh;

    }

}

@media (min-width:640px) and (max-width:1280px)

{

    body{
        background-size: cover;
        background-position: top;
        background-position: center;
        background-image: url(science-fiction-1674554_1280.jpg);
       height: 90vh;
    }
}    

@media (min-width:1280px) and (max-width:1920px)

{

    body{
        background-size: cover;
        background-position: top;
        background-position: center;
        background-image: url(science-fiction-1674554_1920.jpg);
        height: 90vh;
        
    }

}