I would like to read from a .css file and inject it as an inline style in wp_head. it's possible?

i've tried this "Add inline css to theme" solution but it doesn't do what I expect because I expect all the style to be injected into

<style> [mystile.css] </style>

and not

<link href="[mystile.css]">

2 Answers 2


You need to add your css to wp_head. In order to do so, you need to get your dynamic CSS first, load in into a variable and then add that variable to the head output. Just like so:

(This code can go into your functions.php, plugin file or somewhere else in your theme, make sure you include this code in a file where it can be called properly)


  function so_output_dynamic_css() {
    // do some stuff to get your CSS here..
    $some_dynamic_css = "body {background: green;}";
    <style type="text/css" id="so-dynamic-css">
         <?php echo $some_dynamic_css; ?>
  <?php }
  add_action('wp_head', 'so_output_dynamic_css');
  • 1
    it's not exactly my problem ... I don't have a dynamically generated css, I have to get it from a file that was compiled by sass. In addition is more correct to use wp_add_inline_style()
    – Erik
    Jul 23, 2019 at 10:58

I found a solution to include a css file without using "file_get_contents()" since it might require php.ini edits (allow_url_fopen). in other hands wp_add_inline_style() needs a registered style to be outputted and, in this case, i can't use it because this is the above the fold style (the rest were loaded into the footer).

as the @user3135691 had pointed out you need to have a variable all the css and then append it to the head.

my solution is:

function inject_css_style() {

  // get the acf.css file and store into a variable
  include 'wp-content/themes/my-theme/inline.css';
  $atf_css = ob_get_clean();

  // return the stored style
  if ($atf_css != "" ) {
    echo '<style id="inline-css" type="text/css">'. $atf_css . '</style>';
  • Thanks for sharing the solution later on :-) good job. Jul 23, 2019 at 20:54

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