Import CSS files in WordPress - php

Question

I'm trying to migrate my HTML to WordPress template. While I'm doing that, I want to keep my CSS files where they are placed and import them to the code. I found out that I can use functions.php file to make it easier.
Below is the code that I added to functions.php:
<?php
function add_theme_codes() {
wp_enqueue_style(‘bootstrap’,get_stylesheet_directory_uri().’/css/bootstrap_grid.css’, ‘all’);
wp_enqueue_style( ‘style’, get_stylesheet_directory_uri().’/css/main.css’, ‘all’);
}
add_action( ‘wp_enqueue_scripts’, ‘add_theme_codes’ );
?>
But still my WordPress site is not importing the CSS files.

Answer 1

Still you have selected the answer I would like to answer on your last desire that you want this to work in a proper way that WordPress do. Please check wp_footer is called before body tag closed or not. Action Hook wp_enqueue_scripts will called in wp_footer function. Please try once and let me know the result.

Answer 2

You can get css file from below code:
<?php
add_action( 'wp_enqueue_scripts', 'theme_enqueue_styles' );
function theme_enqueue_styles() {
wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
wp_enqueue_style( 'child-style', get_stylesheet_directory_uri() . '/style.css', array('parent-style') );
}
?>
Or in Header section before wp_head() add below code
<link href="<?php echo get_bloginfo('stylesheet_directory');?>/css/bootstrap_grid.css" rel="stylesheet" />
<link href="<?php echo get_bloginfo('stylesheet_directory');?>/css/main.css" rel="stylesheet" />

Answer 3

Wrap with add_action and this might work
<?php
add_action( 'wp_enqueue_scripts', 'theme_enqueue_styles' );
function theme_enqueue_styles() {
wp_register_style('css-ui',get_template_directory_uri().'/assets/css/style.css' );
wp_enqueue_style('css-ui' ); }