Download the style.css file from the example source code and save it in the css subfolder.

style.css file from the example source code.js

// TRUNCATED ./css/style.css

// DO NOT COPY AND PASTE. DOWNLOAD THE FULL FILE HERE https://github.com/cometchat-pro-tutorials/jquery-chat-app/blob/master/css/style.css

* {
  box-sizing: border-box;
}
body {
  color: #333;
  font-size: 13px;
  margin: 0;
  width: 100%;
  height: 100vh;
  -webkit-font-smoothing: antialiased;
}
h3 {
  font-family: 'Abril Fatface';
  margin-bottom: 20px;
}
button {
  border: none;
  width: 100%;
  margin: auto;
  margin-top: 40px;
  cursor: pointer;
  padding: 10px 0;
  background: #1B47DB;
  font-size: 14px;
  color: #fff;
  border-radius: 4px;
  box-shadow: 0 4px 8px 0 #CFDFFF, 0 6px 20px 0 #CFDFFF;
  font-weight: 700;
  transform: perspective(1px) translateZ(0);
}