Glassmorphic Navbar

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Glassmorphic Navbar</title>
    <style>
        /*
        ========================================
        CSS Custom Properties (Glassmorphic Theme)
        ========================================
        The theme is defined by its semi-transparent colors,
        a blur value, and high-contrast text.
        */
        :root {
            /* RGBA is used for transparency. The alpha value (e.g., 0.2) is key. */
            --color-glass-bg: rgba(255, 255, 255, 0.2);
            --color-glass-border: rgba(255, 255, 255, 0.3);
            --color-link-highlight: rgba(255, 255, 255, 0.25);
            
            --color-text: #ffffff; /* Fully opaque white for max contrast */
            --color-focus-outline: #5ab1ff;
            
            --font-family-sans-serif: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
            --font-weight-bold: 600;
            
            --blur-value: 10px;
            --border-radius-soft: 8px;
            --navbar-height: 70px;
            --navbar-padding: 1.5rem;
            --container-width: 1140px;
            --transition-speed: 0.3s;
        }

/*
        ========================================
        Global Resets & Showcase Background
        ========================================
        */
        *,
        *::before,
        *::after {
            box-sizing: border-box;
        }

body {
            margin: 0;
            font-family: var(--font-family-sans-serif);
            font-size: 1rem;
            line-height: 1.5;
            color: var(--color-text);
            
            /* A vibrant background is essential to see the glassmorphism effect. */
            background-image: linear-gradient(45deg, #ff005c, #5200ff);
            background-attachment: fixed; /* Ensures the gradient doesn't scroll with content */
        }
        
        /* Placeholder content to demonstrate scrolling */
        .content {
            padding: calc(var(--navbar-height) + 2rem) var(--navbar-padding);
            height: 200vh;
            color: white; /* Make text readable on gradient */
            text-align: center;
        }
        
        ul { list-style: none; margin: 0; padding: 0; }
        a { text-decoration: none; color: inherit; }

/*
        ========================================
        Main Navbar Structure
        ========================================
        */
        .navbar {
            /* Positioned fixed to stay at the top and show the effect while scrolling */
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: var(--navbar-height);
            display: flex;
            align-items: center;
            z-index: 1000;
            
            /* The Core Glassmorphism Properties */
            background: var(--color-glass-bg);
            border-bottom: 1px solid var(--color-glass-border);
            box-shadow: 0 4px 30px rgba(0, 0, 0, 0.1);
            
            /*
             The `backdrop-filter` property creates the "frosted glass" blur effect.
             Older browsers that do not support this will simply see a semi-transparent navbar.
            */
            backdrop-filter: blur(var(--blur-value));
            -webkit-backdrop-filter: blur(var(--blur-value)); /* For Safari compatibility */
        }

.navbar__container {
            display: flex;
            justify-content: space-between;
            align-items: center;
            width: 100%;
            max-width: var(--container-width);
            margin: 0 auto;
            padding: 0 var(--navbar-padding);
        }
        
        .navbar__brand {
            font-size: 1.5rem;
            font-weight: var(--font-weight-bold);
        }
        
        /* Make text readable against any background with a subtle shadow */
        .navbar__brand,
        .navbar__link {
            text-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
        }

/*
        ========================================
        Mobile Menu & Hamburger Toggle
        ========================================
        */
        .navbar__toggle {
            display: block;
            padding: 0.5rem;
            border: none;
            background: transparent;
            cursor: pointer;
            z-index: 1001;
        }
        
        .navbar__toggle .bar {
            display: block;
            width: 25px;
            height: 3px;
            margin: 5px auto;
            background-color: var(--color-text);
            transition: all var(--transition-speed) ease-in-out;
            border-radius: 2px;
        }

.navbar__toggle.is-active .bar:nth-child(2) { opacity: 0; }
        .navbar__toggle.is-active .bar:nth-child(1) { transform: translateY(8px) rotate(45deg); }
        .navbar__toggle.is-active .bar:nth-child(3) { transform: translateY(-8px) rotate(-45deg); }
        
        .navbar__menu {
            display: none;
            flex-direction: column;
            width: 100%;
            position: absolute;
            top: var(--navbar-height);
            left: 0;
            z-index: -1; /* Place behind the main navbar */

background: var(--color-glass-bg);
            backdrop-filter: blur(var(--blur-value));
            -webkit-backdrop-filter: blur(var(--blur-value));
            border-top: 1px solid var(--color-glass-border);
            padding-bottom: 1rem;
        }
        
        .navbar__menu.is-active { 
            display: flex; 
            background-image: linear-gradient(45deg, #ff005c, #5200ff);
        }

.navbar__item { text-align: center; }

.navbar__link {
            display: block;
            padding: 1.25rem;
            font-weight: var(--font-weight-bold);
            transition: background-color var(--transition-speed) ease;
        }
        
        /* Add a subtle highlight for interaction on mobile */
        .navbar__link:hover, .navbar__link:focus {
            background-color: var(--color-link-highlight);
        }

/* Highly visible focus outline for accessibility */
        :is(.navbar__toggle, .navbar__link):focus-visible {
            outline: 2px solid var(--color-focus-outline);
            outline-offset: 2px;
            border-radius: var(--border-radius-soft);
        }

/*
        ========================================
        Desktop Navbar Styles (Responsive)
        ========================================
        */
        @media (min-width: 768px) {
            .navbar__toggle { display: none; }

.navbar__menu {
                display: flex;
                flex-direction: row;
                align-items: center;
                position: static;
                width: auto;
                background-color: transparent !important;
                background-image: none !important;
                backdrop-filter: none;
                -webkit-backdrop-filter: none;
                border: none;
                z-index: 1;
                padding: 0;
            }
            
            .navbar__list {
                display: flex;
                align-items: center;
            }

.navbar__item { margin-left: 0.5rem; }

.navbar__link {
                padding: 0.6rem 1.1rem;
                border-radius: var(--border-radius-soft);
            }
            
            .navbar__link:hover,
            .navbar__link:focus,
            .navbar__link--active {
                background-color: var(--color-link-highlight);
            }
        }
    </style>
</head>
<body>

<header class="navbar" role="banner">
        <div class="navbar__container">
            <a href="#" class="navbar__brand" aria-label="Homepage">Aura</a>
            
            <button class="navbar__toggle" 
                    id="navbarToggle" 
                    aria-label="Toggle navigation" 
                    aria-controls="navbarMenu" 
                    aria-expanded="false">
                <span class="bar"></span>
                <span class="bar"></span>
                <span class="bar"></span>
            </button>
            
            <nav id="navbarMenu" class="navbar__menu" role="navigation" aria-labelledby="navbarToggle">
                <ul class="navbar__list">
                    <li class="navbar__item"><a href="#" class="navbar__link navbar__link--active">Home</a></li>
                    <li class="navbar__item"><a href="#" class="navbar__link">Features</a></li>
                    <li class="navbar__item"><a href="#" class="navbar__link">Gallery</a></li>
                    <li class="navbar__item"><a href="#" class="navbar__link">Sign In</a></li>
                </ul>
            </nav>
        </div>
    </header>
    
    <main class="content">
        <h1>Glassmorphism in Action</h1>
        <p>Scroll down to see the "frosted glass" effect of the fixed navbar over the page content.</p>
    </main>

if (navbarToggle && navbarMenu) {
                navbarToggle.addEventListener('click', function () {
                    navbarToggle.classList.toggle('is-active');
                    navbarMenu.classList.toggle('is-active');

// Update the aria-expanded attribute for screen readers
                    const isExpanded = navbarToggle.getAttribute('aria-expanded') === 'true';
                    navbarToggle.setAttribute('aria-expanded', !isExpanded);
                });
            }
        });
    </script>
</body>
</html>