.book-wrapper {
  width: 80%;
  max-width: 900px;
  background: white;
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
  border-radius: 10px;
  overflow: hidden;
  padding: 20px;
  border: 5px solid #8b4513; /* Brown */
  margin: 40px auto;
}

.book-header {
  text-align: center;
  font-size: 24px;
  font-weight: bold;
  color: #b30000; /* Red */
  margin-bottom: 15px;
}

.viewer-container {
  position: relative;
  width: 100%;
  height: 600px;
  overflow: hidden;
  border: 3px solid #333; /* Black */
  border-radius: 10px;
}

#pdfFrame {
  width: 100%;
  height: 100%;
  border: none;
}

/* Navigation Buttons */
.nav-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: #006400; /* Green */
  color: white;
  padding: 12px 15px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 18px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.3);
  user-select: none;
}

.nav-btn:hover {
  background: #228b22;
}

#prevBtn {
  left: -55px;
}

#nextBtn {
  right: -55px;
}

@media (max-width: 600px) {

  .book-wrapper {
    width: 95%;
    padding: 10px;
    margin: 20px auto;
    border-width: 3px;
  }

  .book-header {
    font-size: 18px;
    margin-bottom: 10px;
  }

  .viewer-container {
    height: 400px; /* Mobile height */
    border-width: 2px;
  }

  #prevBtn,
  #nextBtn {
    padding: 10px 12px;
    font-size: 15px;
  }

  #prevBtn {
    left: 5px; /* arrows screen ke andar */
  }

  #nextBtn {
    right: 5px; /* arrows screen ke andar */
  }
}