https://codepen.io/legendaryPower/pen/dvJQvB

$(document).ready(function() {
  $("#toggle").click(function() {
    var elem = $("#toggle").text();
    if (elem == "Read More") {
      //Stuff to do when btn is in the read more state
      $("#toggle").text("Read Less");
      $("#text").slideDown();
    } else {
      //Stuff to do when btn is in the read less state
      $("#toggle").text("Read More");
      $("#text").slideUp();
    }
  });
});

@import url('https://fonts.googleapis.com/css?family=Raleway');
#text{
display:none;
}
.btn-container{
  margin: auto;
  height:44px;
  width:166.23px;
  
}
a:active{
  color:#ffd323;
}
body{
   background-color:aqua;
}
button{
  user-select:none;
  -webkit-user-select:none;
  -moz-user-select:none;
  -ms-user-select:none;
  cursor:pointer;
  border:none;
  padding:8px;
  font-size:20px;
  background:linear-gradient(141deg, #0fb8ad 0%, #1fc8db 51%, #2cb5e8 75%);
  color:white;
  font-family:cursive;
  box-sizing:border-box;
}
body{
  font-family:'Raleway',monospace;
  font-size:20px;
  color:white;
}

<h1 align="center">What is CSS?</h1>
Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation of a document written in a markup language.Although most often used to ...user interfaces for web applications, and user interfaces for many mobile applications.

<div><span id="text">xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx</div>

<div class="btn-container"><button id="toggle">Read More</button></div>