アコーディオン：FAQ形式｜Accordion: FAQ Style

<div class="container">
    <div class="accordion">
        <div class="btn-box">
            <button data-default-text="Q: What is this accordion?" data-open-text="Close">Q: What is this accordion?</button>
        </div>
        <div class="more">
            <ul>
                <li>A: This is a simple Q&A style accordion that adopts clean Material Design principles. It displays questions as buttons and provides clear answers when expanded.</li>
            </ul>
        </div>
    </div>
</div>

@keyframes materialFadeIn {
    0% {
        opacity: 0;
        transform: translateY(-10px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}

.accordion {
    margin: 25px 0;
    position: relative;
}

.btn-box button {
    width: 100%;
    padding: 20px 24px;
    background: #f5f5f5;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    color: #333;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    text-align: left;
    position: relative;
    overflow: hidden;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.btn-box button:hover {
    background: #e0e0e0;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
}

.btn-box button:active {
    background: #d5d5d5;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
}

.more {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    background: #fff;
    border-radius: 0 0 8px 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    margin-top: -4px;
    position: relative;
    z-index: 1;
}

.more.appear {
    max-height: 500px;
    animation: materialFadeIn 0.3s ease;
}

.accordion:has(.more.appear) .btn-box button::after {
    transform: translateY(-50%) rotate(180deg);
}

.more ul {
    list-style: none;
    padding: 16px 24px;
    margin: 0;
}

.more li {
    padding: 16px 0;
    color: #333;
    font-size: 15px;
    line-height: 1.6;
    font-weight: 400;
    transition: all 0.2s ease;
}

.more li:hover {
    color: #000;
}

.more li:last-child {
    border-bottom: none;
}

/* レスポンシブ対応 */
@media (max-width: 768px) {
    .btn-box button {
        font-size: 14px;
        padding: 16px 20px;
    }
    
    .more ul {
        padding: 12px 20px;
    }
    
    .more.appear {
        max-height: 400px;
    }
}

document.addEventListener('DOMContentLoaded', function() {
    const buttons = document.querySelectorAll('.btn-box button');
    
    buttons.forEach(button => {
        button.addEventListener('click', function() {
            const more = this.parentElement.nextElementSibling;
            const isOpen = more.classList.contains('appear');
            
            // 他のアコーディオンを閉じる
            document.querySelectorAll('.more').forEach(item => {
                item.classList.remove('appear');
            });
            
            // クリックされたアコーディオンの開閉
            if (!isOpen) {
                more.classList.add('appear');
            } else {
                more.classList.remove('appear');
            }
        });
    });
});