Mohammad Taqui Sayed

For changing the name, you need to redefine the function supernova_category_navigation which is in /lib/functions/custom-functions.php. However if you change the name , you would also need to tweek your css a little bit.
The css you would like to adjust in this case would be padding-left value in .header_cat_title .first_cat class.

Okay fixed and uploaded the new version, it would be a couple of weeks for it to be available for update. However you can download it manually and update from here if you want.
https://wordpress.org/themes/download/supernova.1.6.3.zip

Can I have link to your site please.

Show more buttons loads more posts without reloading the page through ajax. I think its not working probably your blog doesn’t have enough posts for it to work.

Hi,
Sorry there is no hook for changing the default.png image, but probably I’ll add that in the future version , so you can change the default image. But for now a little script can solve your issue I wrote for you.

Just replace the new-default.png to any image you like.

(function($){
    $(document).ready(function(){
        var source, newSrc,
            defaultImage = 'default.png',
            newImage     = 'new-default.png';

        $('img[alt="Default Image"]').each(function(){
            source = $(this).attr('src');
            if( source.indexOf(defaultImage) >= 0 ){
                newSrc = source.replace( defaultImage , newImage );
                $(this).attr('src', newSrc);
            }
        });
    });
})(jQuery);

Thanks, this https://wordpress.org/support/view/theme-reviews/supernova should be right place for the feedback.

No Problem

.home section.main_content { padding: 0; border: none; min-height: 200px;}
.home .entry{padding: 0;}
.home .entry img{width: 100%;}
.home .main_content .post{margin-bottom: 0}
.home section.main_content{min-height:  300px;}
.home .entry p{margin-bottom: 0}

Did not know somebody would try so hard to remove it. (:

Paste this css under Appearance > Supernova Options > Styling > Write Custom CSS

.post img.attachment-thumbnail, .type-post img.attachment-thumbnail{
    box-shadow: none;
    border: none;
    -webkit-box-shadow: none;
    margin: 0 20px 20px 1px;
}