body {
  margin: 0;
  font-family: 'Georgia', serif;
  background: #f5f0e6;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.page {
  display: none;
  width: 90%;
  max-width: 900px;
  height: 80vh;
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
  padding: 40px;
  position: relative;
}

.page.active {
  display: block;
}

.center {
  text-align: center;
}

button {
  padding: 12px 20px;
  font-size: 16px;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  background: #b30000;
  color: white;
}

.arrow {
  position: absolute;
  bottom: 20px;
  font-size: 28px;
  cursor: pointer;
}

.arrow.right {
  right: 25px;
}

.arrow.left {
  left: 25px;
}

/* Envelope */
.envelope {
  width: 200px;
  height: 120px;
  background: #e0d4c2;
  margin: 40px auto;
  position: relative;
  cursor: pointer;
  display: none;
}

.envelope::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  border-left: 100px solid transparent;
  border-right: 100px solid transparent;
  border-top: 60px solid #c8b39a;
}

/* Letter */
.letter {
  display: none;
  background: #fff7e6;
  padding: 25px;
  border-radius: 10px;
  margin-top: 20px;
}

/* Book */
.book {
  display: flex;
  height: 100%;
}

.book-page {
  width: 50%;
  padding: 25px;
  border-right: 1px solid #ddd;
  overflow-y: auto;
}

.book-page:last-child {
  border-right: none;
}

a {
  color: #b30000;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}