.back-to-top-btn {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: #49b0ec86;
    border: 3px solid rgba(255, 255, 255, 0.5);
    color: rgba(255, 255, 255, 0.5);
    box-shadow: 0 0 15px 5px #70707065;
    border-radius: 50%;
    width: 60px;
    height: 60px;
    transition: opacity 0.5s, transform 0.9s;
    opacity: 0;
    z-index: 9999;
    
  }
  @media(min-width: 670px){
    .back-to-top-btn {
      opacity: 0;
      display: none;
  }
  .back-to-top-btn.show {
    opacity: 0;
    display: none;
  }
  .arrow-up{
    opacity: 0;
    display: none;
  }
  .back-to-top-btn {
    opacity: 0;
    display: none;
}
  }

  .back-to-top-btn.show {
    opacity: 1;
    transform: translateY(0);
  }
  
  .back-to-top-btn .arrow-up {
    font-size: 28px;
    color: white;
  }
  
  @keyframes fadeInFromBottom {
      0%{
      transform: translateY(50px);
      opacity: 0;
    }
     25%{
        transform: translateY(37.5px);
        opacity: 0.25;
     }
     50%{
        transform: translateY(25px);
        opacity: 0.5;
     }
     75%{
        transform: translateY(12.5px);
        opacity: 0.75;
     }
     100%{
      transform: translateY(0);
      opacity: 1;
    }
  }
  
  .back-to-top-btn {
    animation: fadeInFromBottom 0.6s;
  }