.box-btn {
  position: absolute;
  bottom: 250%;
  left: 0;
  right: 0;
  text-align: center;
}

.btnnohp {
  padding: 20px 0 30px 0;
  opacity: 1;
  width: 100%;
  max-width: 250px; 
  height: 60px;
  background: none;
  outline: none;
  border: none;
  font-size: 16px;
  text-align: center;
  margin: 0 auto;  
  position: relative; 
  top: -250px; 
}