ポップアップウィンドウ：グラスモーフィズム｜Pop-up Window: Glassmorphism

<div class="container">
    <div id="popup-container">
        <button id="popup-btn" class="popup-btn">Glassmorphism</button>
    </div>
    <div id="popup" class="popup">
        <div class="popup-content">
            <p>Glassmorphism Popup</p>
            <p>A modern popup window with glass-like transparency and blur effects.</p>
        </div>
    </div>
</div>

.container {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}
.container .popup-btn {
    cursor: pointer;
    border: none;
    padding: 12px 24px;
    border-radius: 16px;
    color: #333;
    background-color: #eee;
    font-weight: 600;
    box-shadow: 0 0 4px rgba(0, 0, 0, 0.3);
    display: block;
    margin: 0 auto;
    width: 180px;
}
.container .popup-btn:hover {
    opacity: 0.5;
}
.container .popup {
    position: fixed;
    bottom: -100%;
    left: 50%;
    transform: translateX(-50%);
    z-index: 1001;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    max-width: 90%;
    max-height: 90%;
}
.container .popup.active {
    opacity: 1;
    visibility: visible;
    bottom: 20px;
    transform: translateX(-50%);
    animation: popupShowHide 3.4s ease forwards;
}
@keyframes popupShowHide {
    0% {
        opacity: 0;
        transform: translateX(-50%) translateY(100%);
    }
    20% {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
    80% {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
    100% {
        opacity: 0;
        transform: translateX(-50%) translateY(100%);
    }
}
.container .popup-content {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    padding: 30px;
    border-radius: 20px;
    text-align: center;
    position: relative;
    min-width: 300px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: 0 8px 32px rgba(31, 38, 135, 0.37), 0 0 0 1px rgba(255, 255, 255, 0.18);
    overflow: hidden;
}
.container .popup-content::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: linear-gradient(135deg, rgba(255,255,255,0.1) 0%, rgba(255,255,255,0.05) 100%);
    border-radius: 20px;
    pointer-events: none;
}
.container .popup-content p:first-child {
    font-size: 24px;
    font-weight: bold;
    margin-bottom: 15px;
    color: #333;
    text-shadow: 0 1px 2px rgba(255,255,255,0.8);
}
.container .popup-content p:last-of-type {
    font-size: 16px;
    color: #555;
    margin-bottom: 25px;
    line-height: 1.6;
    text-shadow: 0 1px 2px rgba(255,255,255,0.6);
}

document.addEventListener('DOMContentLoaded', function() {
    const popupBtn = document.getElementById('popup-btn');
    const popup = document.getElementById('popup');
    popupBtn.addEventListener('click', function() {
        popup.classList.add('active');
    });
    popup.addEventListener('animationend', function() {
        popup.classList.remove('active');
    });
});