Check out example codes for "what is responsive design". It will help you in understanding the concepts better.

Code Example 1

/* Answer to: "what is responsive design" */

/*
  Responsive web design is an approach to web design that makes
  web pages render well on a variety of devices and window or screen
  sizes. Recent work also considers the viewer proximity as part of
  the viewing context as an extension for RWD.

  In other words, it makes your website look nice on all devices.

  To learn Responsive Web Design head over to W3Schools tutorial:
  https://www.w3schools.com/css/css_rwd_intro.asp
*/

Code Example 2

<div id="gallery">
            <div class="showcase-images">
                <div class="showcase-block">
            <img id="show-img" src="images/showcase/tabs.png" alt="Tabs">
            </div>
            </div>
            <nav>
            <ul id="main">
                <li id="tabs"><a href="#">Tab</a></li>
                <li id="login"><a href="#">Login</a></li>
                <li id="forum"><a href="#">Forum</a></li>
            </ul>
        </nav>
        </div>

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