.book-title {
  text-align: center;
  font-family: "Comic Sans MS", cursive;
  font-weight: 300;   /* or 400 — removes boldness */
  color: red;
  font-size: 54px;
  /* line-height: 1.5; */
  margin: 60px;
}

.book-subtitle {
  display: block;
  color: green;
  font-size: 30px;
  margin: 30px;        /* neutral baseline */
  position: relative;   /* enables nudging */
  top: 15px;             /* positive = move down, negative = move up */
}

  display: block;
  color: green;
  font-size: 30px;
  

/* optional mobile adjustment */
@media (max-width: 600px) {
  .book-title {
    font-size: 36px;
  }
  .book-subtitle {
    font-size: 22px;
  }
}