body {
  background-image: url("mandelbrot.png");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}
.center-page {
min-height: 100vh;
display: flex;
flex-direction: column;
justify-content: center; /* vertical center /
align-items: center;     / horizontal center */
text-align: center;
gap: 1rem;
position: relative;
z-index: 1;
padding: 1rem;
}

body, .center-page, .center-page * {
color: #ffffff; /* make all text white */
}