.center {
  margin: 0;
  position: absolute;
  top: 50%;
  left: 50%;
  -ms-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
}
#box{
   display: flex;
   border: 5px solid black;
   width: 20vw;
   height: 20vw;
  text-align: center;
   margin: auto;
   background: white;
   flex-direction: column;
   align-items: center;
   justify-content: center;
     flex: 70%;
}
html {
background-image: url("stars.png");
  background-repeat: repeat;
  background-size: auto;
}
h2 {
    display: table;
    margin: 0px auto 0px auto;
    padding: 20px;
    font-size: 20px;
    background-color: white;
    color: black;
    text-align: center;
    font-family: 'Arial';
    font-weight: lighter;
}