style.css

* {
    padding: 0;
    margin: 0;
    font-family: 'Itim';
  }
  
 h1 {
    font-size: 4em;
    text-align: center;
  }

  .intro h2 {
    font-size: 2.1em;
    padding-bottom: 10px;
  }
  
  .intro p {
    text-align: justify;
    font-size: 1.4em;
  }

  .interface h2 {
    font-size: 2.1em;
  }

  .interface p {
    font-size: 1.4em;
  }
  
  .instructions {
    background-color: rgba(0, 67, 119, 0.219);
    text-align: center;
    border-radius: 5px;
    border-style: solid;
    border-color: #047;
    padding: 10px;
  }
  
  body {
    background-color: #ededed;
    padding: 30px;
  }
  
  button {
    padding: 7px;
    background-color: #047;
    color: #fff;
    font-size: 19px;
    border: none;
    margin: 20px auto;
    display: block;
    border-radius: 5px;
  }
  
  button:hover {
    background-color: rgba(0, 67, 119, 0.747);
    transition: 1s;
  }
  
  button:not(hover) {
    transition: 1s;
  }
  
  input {
    width: 50%;
    margin: 10px 25%;
  }
  
  .interface, .result {
    display: none;
  }

  .optionsLeft, .optionsRight {
    display: none;
    text-align: center;
  }

  .right {
      display: none;
  }
  
  .show-frequency, .show-frequency-left, .show-frequency-right {
    background-color: #047;
    color: #fff;
    padding: 30px;
    font-size: 20px;
    margin-top: 25px;
    text-align: center;
    border-radius: 5px;
    border-color: rgb(0, 15, 27);
    border-style: solid;
}