Please do not edit any of the Bricks theme core files directly, as all your changes will be lost, when updating the theme.
Instead, use the Bricks child theme to make modifications, and overwrite files. You can download the Bricks child theme directly from your Bricks account.
Upload this child theme ZIP file (bricks-child.zip) like any other WordPress theme. Go to Appearance > Themes and activate Bricks Child Theme. You can add your own styles to style.css.
You can learn more about how a Child Theme works by visiting the official WordPress Codex: https://developer.wordpress.org/themes/advanced-topics/child-themes/
The functions.php file of a child theme, unlike style.css, does not overwrite the functions.php file of the parent theme. Instead, it is loaded in addition to the parent themes’ functions.php, right before the parent file.