Want to target specific posts in a loop - php

Question

My Wordpress site has a loop that creates posts, and I want to target specific posts to change their css values.
html - index.php
<?php /* Start the Loop */ ?>
<?php while ( have_posts() ) : the_post(); ?>
<?php
get_template_part( 'content' );
?>
<?php endwhile; ?>
content.php
<?php
if (has_post_thumbnail()) {
$thumbnail_data = wp_get_attachment_image_src( get_post_thumbnail_id( get_the_ID() ), 'my-fun-size' );
$thumbnail_url = $thumbnail_data[0];
}
?>
<article id="post-<?php the_ID(); ?>" style="background-image:url('<?php echo $thumbnail_url ?>')" <?php post_class('container-fluid'); ?> >
<div class="container-fluid">
<div class="col-md-12 text-cell">
<h2><?php the_title(); ?></h2>
<?php the_category(', '); ?>
</div>
</div>
</article><!-- /#post -->
It was suggested that I use 'get_post_meta ...' but I am not familiar with how to use it. I just want to change css values (padding, font-size, etc) for different posts

Answer 1

I would suggest using Custom Fields for this, so that you can define the values in the post itself, as opposed to having to edit the code every time you add a new post.
In the post, make sure you have Custom Fields visible (Togglable from screen options at the top)
Then make a field called "Alignment" or whatever you prefer and assign a value to it. (for example 'left')
Then you can add a conditional in the loop.
<?php $alignment = get_post_meta(get_the_ID(),'Alignment',true);
if($alignment) == 'left'):?>
<p>Do stuff and things here...</p>
<?php endif;?>
You can read more about it here: https://codex.wordpress.org/Custom_Fields
Hopefully that will work for you. If you want to get fancier with it, I would suggest looking at the Advanced Custom Fields plugin, which allows a lot more flexibility and options.
EDIT from comments:
1st option:
Set a field of "ExtraCSS" to "color:green;"
<?php $extraCSS = get_post_meta(get_the_ID(),'ExtraCSS',true);?>
<article id="post-<?php the_ID(); ?>" style="background-image:url('<?php echo $thumbnail_url ?>'); <?php echo $extraCSS;?>" <?php post_class('container-fluid'); ?> >
2nd option:
(In your stylesheet:)
article:nth-child(2n+0)
{
color:green;
}
http://www.w3schools.com/cssref/sel_nth-child.asp