ハンバーガーメニュー：ネオン（オーバーレイ）｜Hamburger Menu: Neon Overlay

<div class="container">
    <div class="hamburger-menu">
        <div class="line"></div>
        <div class="line"></div>
        <div class="line"></div>
    </div>
    <div class="overlay"></div>
    <nav class="nav-menu">
        <a href="#">Menu 1</a>
        <a href="#">Menu 2</a>
        <a href="#">Menu 3</a>
        <a href="#">Menu 4</a>
        <a href="#">Menu 5</a>
        <a href="#">Menu 6</a>
        <a href="#">Menu 7</a>
        <a href="#">Menu 8</a>
        <a href="#">Menu 9</a>
        <a href="#">Menu 10</a>
    </nav>
</div>

.container {
    position: relative;
    width: 100%;
    height: 300px;
}

.hamburger-menu {
    width: 36px;
    height: 26px;
    position: absolute;
    top: 20px;
    right: 20px;
    cursor: pointer;
    user-select: none;
    background: #000;
    border: 2px solid #00ff88;
    border-radius: 8px;
    padding: 8px;
    box-shadow: 0 0 20px rgba(0, 255, 136, 0.5);
    transition: all 0.3s;
    z-index: 1001;
}

.hamburger-menu:hover {
    box-shadow: 0 0 30px rgba(0, 255, 136, 0.8);
    transform: scale(1.05);
}

.line {
    background-color: #00ff88;
    height: 2px;
    width: calc(100% - 16px);
    position: absolute;
    transition: all 0.3s ease;
    box-shadow: 0 0 10px rgba(0, 255, 136, 0.8);
    left: 8px;
}

.line:nth-of-type(1) {
    top: 25%;
}

.line:nth-of-type(2) {
    top: 50%;
    transform: translateY(-50%);
}

.line:nth-of-type(3) {
    bottom: 25%;
}

.hamburger-menu.active > .line:nth-of-type(1) {
    top: 50%;
    transform: translateY(-50%) rotate(45deg);
}

.hamburger-menu.active > .line:nth-of-type(2) {
    opacity: 0;
}

.hamburger-menu.active > .line:nth-of-type(3) {
    bottom: 50%;
    transform: translateY(50%) rotate(-45deg);
}

.overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 255, 136, 0.1);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 999;
}

.overlay.active {
    opacity: 1;
    visibility: visible;
}

.nav-menu {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    align-items: center;
    justify-content: flex-start;
    padding: 15px;
    width: 300px;
    background: #000;
    border: 2px solid #00ff88;
    border-radius: 15px;
    box-shadow: 0 0 30px rgba(0, 255, 136, 0.6);
    opacity: 0;
    z-index: 1000;
    max-height: 80%;
    overflow-y: auto;
}

.nav-menu.active {
    display: flex;
    animation: fadeIn 0.5s forwards;
}

.nav-menu a {
    text-decoration: none;
    color: #00ff88;
    padding: 10px;
    margin: 8px;
    border: 1px solid #00ff88;
    border-radius: 8px;
    transition: all 0.3s;
    text-shadow: 0 0 10px rgba(0, 255, 136, 0.8);
    opacity: 0;
    transform: translateY(-20px);
    pointer-events: none;
}

.nav-menu a.show {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.nav-menu a:hover {
    background: #00ff88;
    color: #000;
    box-shadow: 0 0 20px rgba(0, 255, 136, 0.8);
}

@keyframes fadeIn {
    0% {
        top: 45%;
        opacity: 0;
    }
    
    100% {
        top: 50%;
        opacity: 1;
    }
}

document.querySelectorAll('.hamburger-menu').forEach(hamburgerMenu => {
    const container = hamburgerMenu.parentElement;
    const navMenu = container.querySelector('.nav-menu');
    const overlay = container.querySelector('.overlay');

    hamburgerMenu.addEventListener('click', () => {
        hamburgerMenu.classList.toggle('active');
        navMenu.classList.toggle('active');

        if (navMenu.classList.contains('active')) {
            overlay.classList.add('active');
            setTimeout(() => {
                const menuItems = navMenu.querySelectorAll('a');
                menuItems.forEach((item, index) => {
                    setTimeout(() => {
                        item.classList.add('show');
                    }, index * 150);
                });
            }, 300);
        } else {
            const menuItems = navMenu.querySelectorAll('a');
            menuItems.forEach(item => {
                item.classList.remove('show');
            });
            setTimeout(() => {
                overlay.classList.remove('active');
            }, 200);
        }
    });
});