Add a action to enqueue stylesGist for my "WorpdPress: Css Styles and Javascripts in theme development (In depth)" article: https://since1979.dev/wordpress-css-styles-and-javascripts-in-theme-development-in-depth/

functions-styles-scripts-complete.php

<?php
function my_theme_enqueue_styles()
{
  $mytheme = wp_get_theme();
  
  wp_enqueue_style( $mytheme->get('TextDomain') . '-purecss', 'https://unpkg.com/purecss@1.0.0/build/pure-min.css', array(), $mytheme->get('Version') , 'screen' );

  wp_enqueue_style( $mytheme->get('TextDomain') . '-purecss-ie8' , 'https://unpkg.com/purecss@1.0.0/build/grids-responsive-old-ie-min.css', array() , $mytheme->get('Version') , 'screen' );
  wp_style_add_data( $mytheme->get('TextDomain') . '-purecss-ie8' , 'conditional' , 'lte IE 8' );

  wp_enqueue_style( $mytheme->get('TextDomain') . '-purecss-ie9' , 'https://unpkg.com/purecss@1.0.0/build/grids-responsive-min.css', array() , $mytheme->get('Version') , 'screen' );
  wp_style_add_data( $mytheme->get('TextDomain') . '-purecss-ie9' , 'conditional' , 'gt IE 8' );

  wp_enqueue_style( $mytheme->get('TextDomain') . '-styles', get_template_directory_uri() . '/style.css', array(), $mytheme->get('Version') , 'screen' );

  wp_register_style( $mytheme->get('TextDomain') . '-inline-css', false );
  wp_enqueue_style( $mytheme->get('TextDomain') . '-inline-css' );
  wp_add_inline_style( $mytheme->get('TextDomain') . '-inline-css', '* { color: red; }' );
}

add_action( 'wp_enqueue_scripts', 'my_theme_enqueue_styles' );


function my_theme_enqueue_scripts()
{
  $mytheme = wp_get_theme();
  
  wp_deregister_script('jquery');

  wp_register_script( $mytheme->get('TextDomain') . '-scripts', get_template_directory_uri() . '/public/js/app.js', array(), $mytheme->get('Version') , true );
  
  $data_array = array(
    'some_string' => __( 'Some string to translate', 'textdomain' ),
    'themepath' => get_template_directory_uri()
  );
  wp_localize_script( $mytheme->get('TextDomain') . '-scripts', 'object_name', $data_array );

  wp_enqueue_script( $mytheme->get('TextDomain') . '-scripts' );
}

add_action( 'wp_enqueue_scripts', 'my_theme_enqueue_scripts' );


function my_theme_optimize_style_tags( $html , $handle , $href , $media )
{
  return "<link rel='stylesheet' id='{$handle}' href='{$href}' media='{$media}' />" . "\n";
}

add_filter('style_loader_tag', 'my_theme_optimize_style_tags', 10, 4);


function my_theme_optimize_script_tags( $tag , $handle , $src )
{
  $defer = ( $handle == 'my-theme-scripts' ) ? 'async defer' : '';

  return "<script id='{$handle}' {$defer} src='{$src}'></script>" . "\n";
}

add_filter('script_loader_tag', 'my_theme_optimize_script_tags', 10, 3);
?>