Per Søderlind

<p>The CSS Flags plugin / library for WordPress loads a dynamicaly created CSS with responsive flags.</p>
<p><strong>Note:</strong> CSS Flags is not a standalone plugin/library, To display the flags you will have to <a href="https://github.com/soderlind/css-flags/#example-1" rel="nofollow ugc">add code to your theme</a> using your own plugin or theme functions.php</p>
<p>You can <a href="https://soderlind.no/css-flags-plugin-for-wordpress/" rel="nofollow ugc">view the flags at my site</a></p>
<p>Sample CSS:</p>
<pre><code>.css-flag.sami {
    background-image: url('data:image/svg+xml;base64,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');
    height: 100%;
    width: 134.666666667%;
    background-size: 100% 100%;
}
.css-flag.sami-landscape {
    height: 100%;
    width: 134.666666667%;
}
.css-flag.sami-portrait {
    height: 74.2574257426%;
    width: 100%;
}
</code></pre>
<h4>Usage</h4>
<p>The total CSS file size is 4 MB, and you don’t want to send all that data back to the users, so you <strong>must</strong> use one of the following filters in your plugin or theme.</p>
<p><strong>css_flags_countries</strong>: Load flags for one or more countries</p>
<pre><code>add_filter('css_flags_countries', function() {
    return array('no'); // Array with ISO_3166-1_alpha-2 country codes: http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2#Officially_assigned_code_elements
});
</code></pre>
<p><strong>css_flags_regions</strong>: Load the flags for one or more regions. You can choose between europe, oceania, africa, asia, northamerica, southamerica and middleeast.</p>
<pre><code>add_filter('css_flags_regions', function() {
    return array('europe'); //europe, oceania, africa, asia, northamerica, southamerica, middleeast
});
</code></pre>
<p><strong>css_flags_exclude</strong>: Exclude some countries from the list. This filter must be used in combination with the <code>css_flags_countries</code> or <code>css_flags_regions</code> filters</p>
<pre><code>add_filter('css_flags_exclude', function() {
    return array('eu');
});
</code></pre>
<p><strong>css_flags_cachetime</strong>: Change the cache time, default it’s 7200 (60x60x2 = 2 hours)</p>
<pre><code>add_filter('css_flags_cachetime', function() {
    return 172800; // 2 days
});
</code></pre>
<p>If you must (but you shouldn’t), you can load all the  CSS flags using the following:</p>
<pre><code>add_filter('css_flags_countries', function() {
    return array('all'); // load all country flags (don't it's 4MB)
});
</code></pre>
<p>More information at <a href="https://github.com/soderlind/css-flags/" rel="nofollow ugc">GitHub</a></p>
<h4>Credits</h4>
<p>The original CSS file is from http://www.phoca.cz/cssflags/. If you only need the CSS file, grab it there.</p>


CSS Flags library

More than 250 vector based flags for WordPress

Anand Kumar

Digital Liberation

<p>If you are running a WordPress site then sooner or later you need to insert some kind of code to your website. It is most likley a web analytics code like Google Analytics or may be social media script or some CSS stylesheet or may be Custom fonts. This plugin will do all the magic. Even if you want to insert those codes in a custom post type.</p>
<p>All you have to do is adding appropriate html code.</p>
<p>Don’t forget to wrap your code with proper tags.</p>
<pre><code><script type="text/javascript">
YOUR JS CODE HERE
</script>
</code></pre>
<p>Or for CSS:</p>
<pre><code><style type="text/css">
YOUR CSS CODE HERE
</style>
</code></pre>
<h4>Why use this plugin:</h4>
<ul>
<li>To insert CSS and JavaScript codes to <code><head></code> or before <code></body></code>.</li>
<li>To insert code to <code><head></code> of any single page or post.</li>
<li>To insert code to Custom Post Type [New Feature].</li>
</ul>
<p>The plugin should be compatible with WooCommerce.</p>
<h4>What it does not offer</h4>
<ul>
<li>You can’t insert/execute PHP codes.</li>
</ul>
<p>Almost all WordPress theme do support this “Header and Footer Scripts” plugin. If the codes are not appearing in your site [ask for support] or look at your theme file if they have standard <code>wp_head</code> and <code>wp_footer</code> hooks.</p>
<h4>Important Links</h4>
<p>For furhter information you are welcomed to follow these links:</p>
<ul>
<li><strong><a href="https://github.com/anandkumar/header-and-footer-scripts/wiki" rel="nofollow ugc">Read Documentation</a></strong></li>
<li><strong><a href="https://wordpress.org/support/plugin/header-and-footer-scripts/" rel="ugc">Get Support</a></strong></li>
<li><strong><a href="https://github.com/anandkumar/header-and-footer-scripts" rel="nofollow ugc">GitHub Repository</a></strong></li>
</ul>


Header and Footer Scripts

good

Como es posible que al desinstalar el plugin, si no has borrado el script te deje el código ahi metido. Y luego a averiguar de donde vienen los errores. 

Al desinstalar te deja el código

Header and Footer Scripts plugin allows you to add scripts to WordPress site's  and just before closing  tag.

CSS Flags library vs Header and Footer Scripts