Edit in JSFiddle

$('.red-button').click(function(){
    $('.info-box').addClass('red').removeClass('blue');    
});
$('.blue-button').click(function(){    
    $('.info-box').addClass('blue').removeClass('red');  
});

<p class="info-box">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Soluta iure officia explicabo corrupti iste suscipit laboriosam ipsam sapiente obcaecati maxime! Quisquam recusandae nemo sequi est veniam unde odit dicta dolorum.</p>
<button class="red-button">Red</button>
<button class="blue-button">Blue</button>

.info-box {
    background-color: #efefef; /* Light Gray */
    padding: 10px;
}

.red {
    background-color: #FF8F87;
    color: #FFFFFF;
    padding: 40px;
}

.blue {
    background-color: #6EB6FF;
    color: #000000;
    padding: 20px;
}