How to load plugin css into wordpress posts and pages?

you can enqueue a css file:

https://paulund.co.uk/add-stylesheets-to-wordpress-correctly

@sterndata

Thank you very much, you solved my problem.
I have one more question

I can use add_action(‘admin_head’, ‘wpflexgrid_styles’); to add stylesheet to admin page as well.

Is there any function or way using which I can load my stylesheet to both admin as well as normal pages?

add_action(‘admin_head’, ‘wpflexgrid_styles’);
add_action(‘wp_enqueue_scripts’, ‘wpflexgrid_styles’);

this works but may put load since need to load twice.

No, because the 2nd one will not (I think) get called on an admin page. It’s easy to check by viewing the page source.

actually It is single css file which I want to add to both admin as well as pages, I wrote last 2 lines and it worked, I want to know if there is any more efficient way

that is the efficient way!

@sterndata

Thank you very much for the help.