.shadow__btn {
    padding: 10px 20px;
    border: none;
    font-size: 1rem;
    color: #84a1d9;
    border-radius: 7px;
    letter-spacing: 4px;
    font-weight: 700;
    text-transform: uppercase;
    transition: 0.5s;
    transition-property: box-shadow;

  }
  
  .shadow__btn {
    background: #1a374d;
    box-shadow: 0 0 25px #1a374d;
  }
  
  .shadow__btn:hover {
    box-shadow: 0 0 5px #84a1d9,
                0 0 25px #84a1d9,
                0 0 50px #84a1d9,
                0 0 100px #84a1d9;
  }