<p><a href="http://pjdietz.com/wordpress-plugins/custom-css-js/" rel="nofollow ugc">Custom CSS and JS</a> allows you to add stylesheets and JavaScripts to any individual post by adding custom fields. Both CSS and scripts can be either internal or external. Since this is a plugin, the custom CSS and JavaScript are available to any theme used to display the post, as long as the themes call “wp_head”.</p>
<h3>Using the Plugin</h3>
<p>To use the plugin, add any combination of the following custom fields to your post.</p>
<p><strong>custom_css</strong><br />
Add an external stylesheet by adding a custom field with the name <strong>custom_css</strong>. The value of the field should be the path to your css file.</p>
<p><strong>cusrom_css_code</strong><br />
Add an internal stylesheet by adding a custom field with the name <strong>custom_css_code</strong>. Include your CSS code as the value. (Do not include the style tags.)</p>
<p><strong>custom_js</strong><br />
Add an external JavaScript by adding a custom field with the name <strong>custom_js</strong>. The value of the field should be the path to your script.</p>
<p><strong>custom_js_code</strong><br />
Add an internal JavaScript by adding a custom field with the name <strong>custom_js_code</strong>. Include your JavaScript code as the value. (Do not include the script tags.)</p>
<h3>Custom Fields Order</h3>
<ol>
<li>The external styles and scripts are included before the internal ones.</li>
<li>If you include multiple entries for a given field, the entries will be included in order.</li>
</ol>
<h3>Okay, but what if I don’t like those tags?</h3>
<p>Just edit custom-css-js.php and change the constants defined near the top of the file.</p>
<h3>Note</h3>
<p>This plugin only works with individual posts and pages. It does not work for list pages (e.g., the index page, search results).</p>


Custom CSS and JS

Custom CSS and JavaScript allows you to add custom internal and external CSS and JavaScripts to individual posts.

Kevin Batdorf

<p>The missing inline block CSS editor for the Gutenberg editor. Very powerful with synced patterns as well. And it pairs well with global styles.</p>
<p>This plugin is perfect for users looking to add CSS for blocks without needing to create a child theme, or use a bloated plugin. Client safe too. CSS won’t leak outside of the block, and only valid block CSS is persisted.</p>
<p>Star it on <a href="https://github.com/KevinBatdorf/pattern-css" rel="nofollow ugc">GitHub</a><br />
Follow me on Twitter <a href="https://twitter.com/kevinbatdorf" rel="nofollow ugc">@kevinbatdorf</a></p>
<h4>How to</h4>
<ul>
<li>Every block will have a new “Pattern CSS” settings panel</li>
<li>Open it and add any CSS. It will be scoped to the block</li>
<li>To target the block directly, you must use the <code>[block]</code> selector</li>
<li>To target any element <em>inside</em> the block, use the normal CSS selector</li>
<li>Use <code>!important</code> to override your theme styles (use sparingly)</li>
</ul>
<h4>Global Editor</h4>
<ul>
<li>Access global styles under the options menu (three dots) in the top right corner of the editor</li>
<li>Additionaly, you can open from the Pattern CSS block editor controls</li>
</ul>
<h4>Features</h4>
<ul>
<li>Powered by WebAssembly for fast and secure CSS parsing</li>
<li>Smart loading. Only loads the CSS when the block is present</li>
<li>Styles persist when changing themes</li>
<li>Scopes styles to the block so that parent/sibling blocks are not affected</li>
<li>It’s fast</li>
<li>CSS is minified and optimized</li>
<li>It’s safe. Invalid, non-spec CSS is never persisted</li>
<li>Supports reusable (synced or not-synced) patterns</li>
<li>See changes on the page as you make them</li>
<li>Combines adjacent rules (to decrease size)</li>
<li>Minifies colors and math functions to simplify according to spec</li>
<li>Supports CSS nesting</li>
</ul>
<h4>Basic Example</h4>
<pre><code>/* Target the block directly */
[block] {
  background: antiquewhite;
  padding: 2rem;
}
/* Target any inner elements */
a {
  text-decoration-color: burlywood;
  text-decoration-thickness: 2px;
  text-decoration-style: solid !important;
}
a:hover {
  text-decoration-color: darkgoldenrod;
}

/* Output: */
.pcss-a1b7b016{background:#faebd7;padding:2rem}.pcss-a1b7b016 a{text-decoration-color:#deb887;text-decoration-thickness:2px;text-decoration-style:solid!important}.pcss-a1b7b016 a:hover{text-decoration-color:#b8860b}
</code></pre>
<h4>Supports Media Queries</h4>
<pre><code>@media (prefers-color-scheme: dark) {
  [block] {
    border-color: blue;
  }
}

/* Output: */
@media (prefers-color-scheme:dark){.pcss-cddaa023{border-color:#00f}}
</code></pre>
<h4>Combines Rules</h4>
<pre><code>[block] {
  color: red;
}
.bar {
  color: red;
}

/* Output: */
.pcss-3aa0f0fc,.pcss-3aa0f0fc .bar{color:red}
</code></pre>
<h4>Fixes redundant properties</h4>
<pre><code>[block] {
  padding-top: 5px;
  padding-left: 50px;
  padding-bottom: 15px;
  padding-right: 5px;
}

/* Output: */
.pcss-3aa0f0fc{padding:5px 5px 15px 50px}
</code></pre>
<h4>Supports CSS nesting</h4>
<pre><code>[block] {
  padding: 1rem;
  a {
    color: red;
  }
  background: white;
  /* Including media queries */
  @media (prefers-color-scheme: dark) {
    background: black;
    color:white;
  }
}

/* Output: */
.pcss-f526bb2d{background:#fff;padding:1rem;& a{color:red}@media (prefers-color-scheme:dark){&{color:#fff;background:#000}}}
</code></pre>
<p>Check browser support for <a href="https://caniuse.com/css-nesting" rel="nofollow ugc">CSS nesting</a></p>


Pattern CSS – The CSS Editor For Blocks


This is exactly what I need. Very easy to use. Love that you can scope to current item with [block] {}



JANUARY 2025 UPDATE: after a year of use and having installed on at least 20 client sites, I now look at this as indispensable to my work as a website developer. No complaints whatsoever.


really, really great CSS control

Add a CSS editor to your blocks and patterns! Loads only where necessary. Supports adding global CSS too.

Custom CSS and JS vs Pattern CSS – The CSS Editor For Blocks