.flex-box {
  display: flex;
  width: 800px;
  height: 500px;
  border: 5px solid green; /* Optional */
  box-sizing: border-box; /* Ensures size includes border/padding */
  min-height: 30vh;
  justify-content: center; /*centers items on the line (the x-axis by default)*/
  align-items: center; /*centers items on the cross-axis (y by default)*/
}

body{
  background: black;
  overflow: hidden;
  position: absolute;
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center; /*centers items on the line (the x-axis by default)*/
  align-items: center; /*centers items on the cross-axis (y by default)*/
}

#enter {
  position: relative;
  left: 22%;
  color: white;
  
}