Navigation bar height can't be resized if child them is used

I tried to use Child theme. If i use sticky menu unnecessary top/bottom padding is added and it can't be reduced. Everything is fine if i use the parent theme. Am I missing anything?

style.css:

/* 
 Theme Name:     My Custom Theme
 Author:         MyCustom
 Author URI:     https://example.com
 Template:       generatepress
 Version:        0.1.1
 Description:    Custom Theme
*/ 

function.php:

<?php 

function my_assets() { 

    wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );

} 
add_action( 'wp_enqueue_scripts', 'my_assets' );