Question: I am building a website using wordpress theme. I have two elements (one floated left, second floated right) in the footer. I need to make it centered (the second one below the first one) when I resize the browser window. I guess I need to set `float:none;` in the media queries and center it somehow, but I wasn't able to figure it out.

[WEBPAGE LINK](http://svycarsky-dum-responsive.geneweb.cz/)

**HTML**

```
<div class="site-info">
      <div style="margin:0 auto; width: 75%;">
        <p style="float:left;">&copy; Copyright <?= date('Y'); ?> Hotel Švýcarský Dům</p>
        <div style="float:right;">Naleznete nás na sociálních sítích: 
          <a style="display: block; float:right; margin:-4px 0 0 5px;" href=""><img src="/wp-content/themes/adamos/images/gplus.png" /></a>
          <a style="display: block; float:right; margin:-4px 5px 0 5px;" href=""><img src="/wp-content/themes/adamos/images/facebook.png" /></a>
        </div>
        <div class="clear"></div>
      </div>
    </div><!-- .site-info -->

```

I attach a picture so you could look at how I want it to look like when you resize the window under 800px.![PICTURE](https://i.stack.imgur.com/eDD5I.png)

Answer: 
This is not a loss of polymorphism. This is a lack of [duck typing](https://stackoverflow.com/questions/1079785/whats-an-example-of-duck-typing-in-java). When the compiler, statically, only knows that it's a `Student` it wont allow you to call non `Student` methods. Even though you know that, at run time, it will be available the static typing system of java says no. Other languages have duck typing that wouldn't care. Java isn't one of them.
`std` is of type `Student`, and it may hold refrences to objects that are not an `AthleteStudent`. Therefore, you can't call `std.changeDepartement()` without an explicit cast to `AthleteStudent`.