styles.css

html, body {
  width: 100%;
  height: 100%;
}

#print-shop-modal {
  display: none;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  max-width: 95%;
  max-height: 95%;
  width: 1000px;
  height: 800px;
  background: #FFFFFF;
  border: 1px solid black;
}

  #print-shop-modal__close-modal-btn {
    width: 100%;
    background: #FFFFFF;
    border: none;
    height: 40px;
    font-size: 18px;
    border-bottom: 1px solid grey;
    text-align: right;
    padding-right: 40px;
    cursor: pointer;
  }

  #print-shop-modal__iframe {
    width: 100%;
    height: 100%;
    border: none;
  }

#image-to-use-input {
  width: 100%;
  max-width: 500px;
  height: 40px;
  font-size: 14px;
}

#buy-image-btn {
  margin-top: 20px;
  display: block;
  width: 200px;
  font-size: 16px;
  height: 40px;
  border: 1px solid black;
}