styles.css

 html {
    box-sizing: border-box;
    font-size: 16px;
  }
  
  *,
  *:before,
  *:after {
    box-sizing: inherit;
  }
  
  body,
  h1,
  h2,
  h3,
  h4,
  h5,
  h6,
  p,
  ol,
  ul {
    margin: 0;
    padding: 0;
    font-weight: normal;
  }
  
  ol,
  ul {
    list-style: none;
  }
  
  img {
    max-width: 100%;
    height: auto;
  }
  
  textarea,
  textarea:hover,
  textarea:focus,
  button[type="button"],
  button[type="button"]:hover,
  button[type="button"]:focus {
    background: inherit;
    border:  none;
    color:  inherit;
    font: inherit;
    outline: none;
  }
  
  textarea {
    resize: none;
    width: 65vw;
    align-items: center;
  }
  
  html {
    font-family:  'Inter', sans-serif;
  }
  
  body {
    background-color: #f3f5fc;
  }
  
  /* =================
   * 3. Breakpoints
   * =================
   * Los breakpoints sirven para cambiar el diseño
   * de la página en puntos claves
   */
  /* ==============
   * 3.1 Celular
   * ==============
   */
  .principal {
    min-height: 75vh;
  }
  
  .logo {
    height: 3rem;
  }
  
  .d-flex {
    display: flex;
  }
  
  .d-none {
    display: none;
  }
  
  .flex-column {
    flex-direction: column;
  }
  
  .flex-row {
    flex-direction: row;
  }
  
  .flex-grow {
    flex-grow: 1;
  }

  .foot{
    width: 100%;
}
  
  #entrada {
    text-align: center;
    font-size: 2rem;
    max-width: 100%;
    margin: 2rem;
    color: #0a3871;
    border: none;
    background-color: #f3f5fc;
  }
  
  ::placeholder {
    color: #7387a4;
  }
  
  .controles {
    padding: 1.5rem;
  }
  
  header {
    margin-top: 1.5rem;
    padding-left: 1rem;
  }
  
  .advertencia {
    height: 2rem;
    font-size: 1rem;
    justify-content: center;
    align-items: center;
  }
  
  button.button {
    color: #0A3871;
    border: solid 1px #0A3871;
    border-radius: 1.5rem;
    padding: 1rem;
    margin: 0.5rem 0px;
    cursor: pointer;
    
  }
  
  button.button:hover,
  button.button:focus {
    background-color: #0A3871;
    color: #fff;
    border: solid 1px #000;
  }
  
  .barra-lateral {
    background-color: #fff;
    border: solid 1px #ddd;
    border-radius: 1rem;
    margin: 1rem;
    padding: 1rem;
    min-height: calc(25vh - 2rem);
    color: #495057;
  }
  
  .my-auto {
    margin-top: auto;
    margin-bottom: auto;
  }
  
  .info {
    text-align: center;
  }
  
  .icon-info {
    width: 1rem;
    height: 1rem;
    display: inline-block;
    background: url('./assets/Vector.png');
    margin: 0px 0.5rem;
  }
  
  .info-txt strong{
    color: #343A40;
    font-size: 1.5rem;
    font-weight: bold;
  }
  
  .barra-lateral {
    position: relative;
  }
  
  .barra-lateral .button {
    visibility: hidden;
    top: 1rem;
    right: 2.5rem;
    border-radius: 1.5rem;
    padding: 0.5rem;
    width: 80px;
    height: 50px;
    font-size: 14px;
    position: absolute
  }
  
  .barra-lateral.con-salida .button {
    visibility: visible;
  }
  
  .barra-lateral.con-salida .info {
    display:  none;
  }
  
  #salida {
    font-size: 1.5rem;
    max-width: 100%;
    word-break: break-all;
    overflow-y: auto;
  }
  
  /* =============
   * 3.2 Tablet
   * =============
   */
  @media only screen and (min-width: 375px) {
    .d-sm-flex {
      display:  flex;
    }
  
    .flex-sm-column {
      flex-direction: column;
    }
  
    .flex-sm-row {
      flex-direction: row;
    }
  
    .flex-sm-grow {
      flex-grow: 1;
    }
  
    button.button {
      border-radius: 1rem;
      margin: 0px 1rem;
    }

    .foot{
        width: 100%;
    }

    .barra-lateral .button{
      position: relative;
      right: 1rem;
    }
  
  }
  /* ==============
   * 3.3 Desktop
   * ==============
   */
  @media only screen and (min-width: 768px) {
    .d-md-flex {
      display:  flex;
    }
  
    .d-md-block {
      display: block;
    }
  
    .flex-md-column {
      flex-direction: column;
    }
  
    .flex-md-row {
      flex-direction: row;
    }
  
    .flex-md-grow {
      flex-grow: 1;
    }
  
    .principal {
      width: 70%;
    }
  
    .barra-lateral {
      width: 30%;
    }
  
    body {
      height: 100vh;
    }
  }

  footer {
    position: absolute;
    font-weight: 200;
    justify-content: space-evenly;
    padding: 0.1rem;
    background: #E5E5E5;
    border-top: 1px solid #0A3871;
    top: 730px;
    }

    footer > p {
    margin: 0.3rem;
    font-size: 12px;
    font-family: 'Inter', sans-serif;
    }

    .slider:before {
      position: absolute;
      content: '';
      height: 6px;
      width: 6px;
      left: 4px;
      bottom: 4px;
      background-color: white;
      -webkit-transition: .4s;
      transition: .4s;
    }

    input:checked + .slider {
      background-color: white;
    }

    input:checked + .slider:before {
      background-color: #000;
    }

    input:focus + .slider {
      box-shadow: 0 0 1px #2196F3;
    }

    input:checked + .slider:before {
      transform: translateX(16px);
    }

    .slider.round {
      border-radius: 34px;
    }

    .slider.round:before {
      border-radius: 50%;
    }

    .toggle{
      position: absolute;
      display: inline-block;
      width: 40px;
      height: 14px;
      top: 80px;
      left: 12px;
    }

    .dark-mode{
      background: #192229;
      color: #fff
    }

    .toggle input{
      opacity: 1;
      width: 0;
      height: 0;
    }

    .slider{
      position: absolute;
      cursor: pointer;
      top: 0;
      left: 5;
      right: 5;
      bottom: 0;
      background-color: black;
      -webkit-transition: .4s;
      transition: .4s;
    }

    .animation{
      animation: floating 6s infinite ease-in-out;
    }

    @keyframes floating {
      0% {
        transform: translatey(0px);
      }
      50% {
        transform: translatey(40px);
      }
      100% {
        transform: translatey(0px);
      }
    }

    @font-face {
      font-family:  'Inter';
      src: url('./fonts/Inter-Light.ttf')
    }
    
    @font-face {
      font-family:  'Inter';
      src: url('./fonts/Inter-Bold.ttf')
    }

    .copy-text button:before {
      content: "Copiado";
      position: absolute;
      top: -35px;
      right: 20px;
      background: #5c81dc;
      padding: 8px 10px;
      border-radius: 20px;
      font-size: 15px;
      display: none;
    }

    .copy-text button:after{
      content: "";
      position: absolute;
      top: -10px;
      right: 70px;
      width: 10px;
      height: 10px;
      background: #5c81dc;
      transform: rotate(45deg);
      display: none;
    }

    .copy-text.active button:before,
    .copy-text.active button:after{
      display: flex;
    }

    .fa-circle-check{
      color: black;
      font-size: 16px;
    }