<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>

<body>
  <button id="night-mode-js" class="btn night-mode" data-text-swap="day-mode" onclick="toggleBtn()">
  Night-mode
  </button>
  
  <div class="quote-container">
    <h2 id="heading">Motivational Quotes</h2>
    <p id="quote-js" class="quote-display">Do not wait; the time will never be ‘just right.’ Start where you stand, and work with whatever tools you may have at your command, and better tools will be found as you go along. — George Herbert</p>
    <button id="quote-btn">Get a quote</button>
  </div>

</body>

</html>
.btn {
  width: 120px;
  height: 30px;
  display: block;
  margin: 0 auto;
  border-radius: 30px;
  font-family: helvetica;
  text-align: center;
  text-transform: uppercase;
  background-color: white;
  border: 1px solid black;
  cursor: pointer;
}
.quote-container {
  max-width: 700px;
  min-width: 350px;
  margin: 30px auto;
  text-align: center;
  border: 2px solid #37474F;
  border-radius: 10px;     
  transition: all 0.5s ease-in;
  color: #37474F;
  font-family: helvetica;
#heading {
    font-size: 28px;
  }
  .quote-display {
    line-height: 30px;
    margin: 30px;
    padding: 20px;
    border: 1px solid #BDBDBD;        
    font-style: italic;
    font-size: 18px;
  }
  #quote-btn {
    margin: 20px;  
    text-transform: uppercase;
    background-color: white;
    border: 1px solid #9E9E9E;
    padding: 10px 30px;
    cursor: pointer;
    transition: background-color 0.3s ease-in;
    &:hover {
      background-color: #37474F;
      color: white;
    }
  }  
}
.night-mode {
  background-color: #37474F;
  color: white;   
}
View Compiled

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js