.parent {
  display: grid;
  place-items: center;
  
  background: lightblue;
  width: 500px;
  height: 500px;
  
  resize: both;
  overflow: auto;
}

.child {
  // etc.
  padding: 0.5rem;
  border-radius: 10px;
  border: 1px solid red;
  background: lightpink;
  font-size: 2rem;
  text-align: center;
}

body {
  font-family: system-ui, serif;
}