html{
    background-image: url("kosmos.jpg");
    font-family: sans-serif;
    display: flex;
        flex-flow: row nowrap;  
        justify-content: center;
        align-content: center;
        align-items: center;
        height:100%;
        margin: 0;
        padding: 0;
}

h1{
    background-color:white;
}
h2{
    background-color:antiquewhite;
}
a{
    font-size: 60px;
    text-decoration: none;
    color:red;
    background-color: blue;
    transition: linear 0.5s;
}
a:hover{
    font-size: 60px;
    text-decoration: none;
    color:blue;
    background-color: red;
    transition: linear 0.5s;
}
#napis{
    background-color: cyan;
    text-align: center;
}
#napis1{
    background-color:blueviolet;
    text-align: center;
}
#napis2{
    background-color:crimson;
    text-align: center;
}
#napis3{
    background-color:gold;
    text-align: center;
}