.main-block {
  width: calc(100% - 280px);
  height: 100vh;
  height: calc(var(--vh, 1vh) * 100);
  position: relative;
}

.back-page-arrow,
.next-page-arrow {
  width: 50px;
  height: 50px;
  background-color: #262F34;
  border-radius: 50%;
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  opacity: .6;
  display: flex;
  justify-content: center;
  align-items: center;
}

.back-page-arrow.disabled,
.next-page-arrow.disabled {
  display: none;
}

.back-page-arrow {
  left: 16px;
}

.next-page-arrow {
  right: 16px;
}

.back-page-arrow::after,
.next-page-arrow::after {
  content: "";
  width: 18px;
  height: 18px;
  border-bottom: 2px solid #fff;
  display: block;
}

.back-page-arrow::after {
  border-left: 2px solid #fff;
  transform: rotate(45deg);
  margin-left: 6px;
}

.next-page-arrow::after {
  border-right: 2px solid #fff;
  transform: rotate(-45deg);
  margin-right: 6px;
}

#my_pdf {
  border: none;
  height: 100%;
  width: 100%;
  vertical-align: bottom;
  max-width: 100%;
}

@media screen and (max-width: 768px) {
  .main-block {
    width: 100%;
    padding-top: 60px;
  }

  .back-page-arrow,
  .next-page-arrow {
    width: 40px;
    height: 40px;
    transform: translateY(calc(-50% + 30px));
  }

  .back-page-arrow {
    left: 14px;
  }
  
  .next-page-arrow {
    right: 14px;
  }

  .back-page-arrow::after,
  .next-page-arrow::after {
    content: "";
    width: 14px;
    height: 14px;
  }

  #my_pdf {
    height: 100vh;
    height: calc(calc(var(--vh, 1vh) * 100) - 60px);
  }
}