Modify the slider height in different pages of a blog

Hello,

I’m designing a WordPress site which hosts a Slider and a Blog with pagination directly in the Home/Main Page.

The problem is that I would like to modify the height of that Slider once any user click on the 2nd page (and following) of that blog using the pagination system. Specifically, the Slider of the Main Page is 750 px and, on the 2nd and following pages of the blog, I would like to reduce the height of that Slider to 500 px.

For more details, here I show you the code I’m currently using. I’m not a professional developer so it’s probably full of errors. However, any suggestion will be more than welcomed.

CSS (on general css panel of the wordpress theme)

.postid-33 .paged .parallax_slider_outer {
    height: 500px;
}

or

PHP (on single.php)

<?php if( is_page() && is_paged() ) { ?>
get_slider('slidertest');
height:500px;
<?php } ?>

Regards,
Ric