adding custom stylesheet to wp-admin

im having troubles getting my custom stylesheet work on WP-ADMIN area.
plugins_url('style.css', __FILE__) ); do i have to create folder in my plugins named css or do i just copy my .css to the wp-admin/css directory?

i tried both it doesnt seem to work for me.

and what values should be replaced to __FILE__?

sorry im kinda new to these stuff.

/*ADDS STYLESHEET ON WP-ADMIN*/
add_action( 'admin_enqueue_scripts', 'safely_add_stylesheet_to_admin' );
    function safely_add_stylesheet_to_admin() {
        wp_enqueue_style( 'prefix-style', plugins_url('style.css', __FILE__) );
    }


/*ADDS MY CUSTOM NAVIGATION BAR ON WP-ADMIN*/
add_action('admin_head', 'custom_nav');
function custom_nav(){
    include('custom_nav.html');

}

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

According to WordPress Codex (here):

admin_enqueue_scripts is the first action hooked into the admin
scripts actions.

Example

Loading a CSS or JS files for all admin area:

//from functions.php

//First solution : one file
//If you're using a child theme you could use:
// get_stylesheet_directory_uri() instead of get_template_directory_uri()
add_action( 'admin_enqueue_scripts', 'load_admin_style' );
function load_admin_style() {
    wp_register_style( 'admin_css', get_template_directory_uri() . '/admin-style.css', false, '1.0.0' );
    //OR
    wp_enqueue_style( 'admin_css', get_template_directory_uri() . '/admin-style.css', false, '1.0.0' );
}

//Second solution : two or more files.
//If you're using a child theme you could use:
// get_stylesheet_directory_uri() instead of get_template_directory_uri()
add_action( 'admin_enqueue_scripts', 'load_admin_styles' );
function load_admin_styles() {
    wp_enqueue_style( 'admin_css_foo', get_template_directory_uri() . '/admin-style-foo.css', false, '1.0.0' );
    wp_enqueue_style( 'admin_css_bar', get_template_directory_uri() . '/admin-style-bar.css', false, '1.0.0' );
}

do i have to create folder in my plugins named css or do i just copy
my .css to the wp-admin/css directory?

No, put your CSS file together with the other, in your theme directory, then specify the path with:

get_template_directory_uri() . '/PATH_TO_YOUR_FILE'

For ex my file name is admin-style.css and i put it in a folder named css my path will looks like:

get_template_directory_uri() . '/css/admin-style.css'

Hope it helps!

Method 2

If you want to make CSS changes for the admin panel. paste the below code in functions.php of your child theme

add_action('admin_head', 'my_custom_fonts'); // admin_head is a hook my_custom_fonts is a function we are adding it to the hook

function my_custom_fonts() {
  echo '<style>
    #posts-filter table.posts{
        table-layout:auto;   
    }
  </style>';
}

Method 3

For those who want add CSS file in admin area from custom plugin (or plugin’s folder):

if (is_admin()) {

Get src if file in folder:
(..myPluginFolder/myfolder/css/my.css)

$myCssFileSrc = plugins_url( '/myfolder/css/my.css', __FILE__ );

Get src if file in root plugin folder:
(..myPluginFolder/my.css)

$myCssFileSrc = plugins_url( 'my.css', __FILE__ );

Enqueue (activate) stylesheet file:

wp_enqueue_style( 'my-css', $myCssFileSrc );
} //endif;

All manipulation in main plugin file (myplugin.php)

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0