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HTML

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Insecure Resource

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CSS

About CSS Preprocessors

CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

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JavaScript

About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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Packages

Add Packages

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HTML 

              
                <!-- 
Change the class string "logged-in" below to see the style adapt
-->
<div class="logged-in">
	<div class="fake-wp-admin-bar">Fake WP Admin Bar</div>
	<nav class="menu-bar">Lots of great menu items would be here.</nav>
	<div class="main-content">
		<h1>Such great content here</h1>
		<p>Lorem ipsum dolor sit amet consectetur, adipisicing elit. Dolores asperiores dicta dolorem qui unde cumque. Vero fugiat voluptatum deleniti commodi dolor officia qui, libero modi velit veniam maxime at esse!</p>
		<p>Lorem ipsum dolor sit amet consectetur, adipisicing elit. Dolores asperiores dicta dolorem qui unde cumque. Vero fugiat voluptatum deleniti commodi dolor officia qui, libero modi velit veniam maxime at esse!</p>
		<p>Lorem ipsum dolor sit amet consectetur, adipisicing elit. Dolores asperiores dicta dolorem qui unde cumque. Vero fugiat voluptatum deleniti commodi dolor officia qui, libero modi velit veniam maxime at esse!</p>
	<div class="add-height"></div>
	</div>
</div>
!

CSS 

              
                :root {
	// 1. Set up the constant values
	// It's best practice to keep custom property values unit-less, lest you run into issues I don't understand well enough to explain here.
	--login-bar-height: 0;
	--menu-bar-height: 50;
}

// 2. Conditionally adjust the height of the login bar based on WordPress' values.
// if body has class "logged-in" and screen is > 783px, update the value.
.logged-in { // This class is added to <body> by WordPress
	@media ( min-width: 783px ) { // Breakpoint comes from WordPress
		--login-bar-height: 32;
	}
}

// 3. Bind the custom property values to regular properties.
// When the login bar isn't here, the value of the --login-bar-height 
// property will be 0 because of our conditional above. 
// So satisfying and clean and great!!!
// Is CSS a programming language?
.menu-bar {
	// Fix the menu bar. This would also work for an absolutely positioned bar.
	width: 100%;
	position: fixed;
	
	// Use calc to apply a unit to the custom property value
	top: calc( var( --login-bar-height ) * 1px ); 
	height: calc( var( --menu-bar-height ) * 1px );
}

.main-content {
	// Pad the top of the content to account for both the menu and login bar height.
	padding-top: calc( ( var( --menu-bar-height ) + var( --login-bar-height ) ) * 1px );
}









// Not part of the algorithm

.stuff {
	height: 1000px;
}

.menu-bar {
	background-color: skyblue;
	display: flex;
	align-items: center;
	justify-content: center;
}

.fake-wp-admin-bar {
	display: none;
	height: 32px;
	z-index: 100;
	color: white;
	background-color: #666;
	top: 0;
	left: 0;
	position: relative;
	width: 100%;
	
	.logged-in & {
		display: block;
	}
	
	@media ( min-width: 783px ) {
		position: fixed;
	}
}

.add-height {
	height: 1000px;
	background: peachpuff;
}
!

JS
!
999px

Console