Style for small screen with UIkit

Question

How can I set different style for some element on small screen when one block move under another? For example: make first block red.

<style type="text/css">
    #block1 {
        background: skyblue;
    }

    #block2 {
        background: yellow;
    }

    /*
    #block1 on small screen {
        background: red;
    }
    */
</style>

<div class="uk-grid">
    <div id="block1" class="uk-width-small-2-3">
         BLOCK 1
    </div>
    <div id="block2" class="uk-width-small-1-3">
         BLOCK 2
    </div>
</div>

jsfiddle

Answer 1

Could this help?

Updated fiddle

#block1 {
    background: skyblue;
}

#block2 {
    background: yellow;
}

@media screen and (max-width: 480px) {  
  #block1 {
    background: red;
  }
}