Image not spanning the whole width on Apple devices

I am developing a WordPress theme at the site;

DELETED

I have a slider at the top which is suppose to spanning the width of the device which is does for Windows and Android devices. However, for Apple devices, Mac, iPad, iPhone it is contrained to the width of the main content at 1280px.

The HTML/PHP code is

<div class="full-width page-style">

        <?php 

            if( have_posts() ):

                while( have_posts() ): the_post(); ?>

                    <?php the_content(); ?>

                <?php endwhile;

            endif;

        ?>

</div>

The CSS is

.full-width {
    max-width: 1280px;
    overflow: inherit;
    padding: 0px 25px!important;
    background: transparent!important;
    border: none!important;
    margin-left: auto;
    margin-right: auto;
}

.page-style {
    background-color: #ffffff;
    border: 1px solid #eeeeee;
    margin-bottom: 30px;
    padding: 25px;
    padding-top: 20px;
    padding-bottom: 25px;
    min-height: 800px;
    overflow: auto;
}

I have tried to edit both the code and CSS to no avail, and I have also tried to inspect the page below to see if I can figure out how they achieved it;

http://layouts.siteorigin.com/layout/fitness-gym/

The issue definately lies with the HTML/CSS mark up rather than the content. I think I must be missing something simple in my HTML for Apple devices.