Weird Issue with jQuery Datepicker

Weird Issue with jQuery Datepicker

I'm facing a weird issue with the jQuery datepicker. The datepicker works perfectly on my localhost; however when I put my files on the server - the datepicker loses styling when I shrink the browser to simulate mobile width. 

Here's my jQuery - 

$("#resumeBirthday").datepicker({
    yearRange: "1930:2000",
    prevText: '<i class="fa fa-chevron-left"></i>',
    nextText: '<i class="fa fa-chevron-right"></i>',
    changeMonth: true,
    changeYear: true,
    dateFormat: "dd MM yy",
    maxDate: '0'
});

Here's my HTML - 

<!-- Birth Date Section -->
<div class="section colm colm4">
    <label class="field prepend-icon">
        <input type="text"  id="resumeBirthday" name="resumeBirthday" class="gui-input" placeholder="Birth Date" value="<?php echo $getPostMeta['resumeBirthday']; ?>">
        <span class="field-icon"><i class="fa fa-calendar"></i></span>
    </label>
</div><!-- end Birth Date section -->

Here's how the datepicker looks when I access it from my mobile on my server. 


Note: This works perfectly well when I'm using localhost! I see it as jS related issue over CSS.