body {
    background-color: lightblue; 

    font-family: Arial, sans-serif;
  }
   .row {
    border: 1px solid black;
  }

  [class^="col-"] {
    border: 1px solid black;
  }

  @media only screen and (max-width: 600px) {
    body {
      font-size: 14px;
    }
  }

  @media only screen and (min-width: 600px) and (max-width: 900px) {
    body {
      font-size: 16px;
    }
  }

  @media only screen and (min-width: 900px) {
    body {
      font-size: 18px;
    }
  }