ポップアップウィンドウ：角に折れ目｜Pop-up Window: Paper Fold

<div class="container">
    <div id="popup-container">
        <button id="popup-btn">Paper Fold</button>
    </div>
    <div id="popup" class="popup">
        <div class="popup-content">
            <p>Paper Fold Popup</p>
            <p>A popup with a three-dimensional design like folded paper.</p>
        </div>
    </div>
</div>

#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;
}

#popup-btn:hover {
    opacity: 0.5;
}

.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%;
}

.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%) rotateX(15deg) rotateY(-15deg);
    }
    20% {
        opacity: 1;
        transform: translateX(-50%) translateY(0) rotateX(0deg) rotateY(0deg);
    }
    80% {
        opacity: 1;
        transform: translateX(-50%) translateY(0) rotateX(0deg) rotateY(0deg);
    }
    100% {
        opacity: 0;
        transform: translateX(-50%) translateY(100%) rotateX(-15deg) rotateY(15deg);
    }
}

.popup-content {
    background: #ffffff;
    padding: 40px;
    border-radius: 0;
    text-align: center;
    position: relative;
    min-width: 320px;
    box-shadow: 
        0 0 0 1px #e0e0e0,
        0 8px 16px rgba(0,0,0,0.1),
        0 4px 8px rgba(0,0,0,0.05);
    animation: paperFold 0.6s ease-out;
}

@keyframes paperFold {
    0% {
        opacity: 0;
        transform: scale(0.8) rotate(5deg);
    }
    100% {
        opacity: 1;
        transform: scale(1) rotate(0deg);
    }
}

.popup-content::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 0 30px 30px 0;
    border-color: transparent #f0f0f0 transparent transparent;
    box-shadow: -2px 2px 4px rgba(0,0,0,0.1);
}

.popup-content::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 0 25px 25px 0;
    border-color: transparent #e0e0e0 transparent transparent;
}

.popup-content p:first-child {
    font-size: 28px;
    font-weight: bold;
    margin-bottom: 20px;
    color: #2c3e50;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.1);
    border-bottom: 3px solid #3498db;
    padding-bottom: 10px;
    font-family: 'Georgia', serif;
}

.popup-content p:last-of-type {
    font-size: 16px;
    color: #555;
    margin-bottom: 0;
    line-height: 1.8;
    font-weight: 400;
    font-style: italic;
}

@media (max-width: 768px) {
    .popup-content {
        padding: 30px;
        min-width: 300px;
    }
    
    .popup-content p:first-child {
        font-size: 24px;
    }
    
    .popup-content p:last-of-type {
        font-size: 14px;
    }
    
    #popup-btn {
        padding: 10px 20px;
        font-size: 14px;
    }
}

@media (max-width: 480px) {
    .popup-content {
        padding: 25px;
        min-width: 280px;
    }
    
    .popup-content p:first-child {
        font-size: 22px;
    }
    
    .popup-content p:last-of-type {
        font-size: 13px;
    }
    
    #popup-btn {
        padding: 8px 16px;
        font-size: 13px;
    }
}

document.addEventListener('DOMContentLoaded', function() {
    const button = document.getElementById('popup-btn');
    const popup = document.getElementById('popup');
    
    if (button && popup) {
        button.addEventListener('click', function() {
            popup.classList.add('active');
        });

        // アニメーション終了後にポップアップを閉じる
        popup.addEventListener('animationend', function() {
            popup.classList.remove('active');
        });
    }
});