/* style.css */
body { max-width: 800px; margin: 40px auto; padding: 0 20px; line-height: 1.6; font-family: sans-serif; }

details { 
    display: block; 
    background: #f4f4f4; 
    padding: 10px; 
    margin: 10px 0; 
    border-radius: 5px; 
}
summary { 
    cursor: pointer; 
    font-weight: bold; 
    list-style: none;
}
summary::before { content: "▶ "; }
details[open] > summary::before { content: "▼ "; }

footer { margin-top: 50px; font-size: 0.8em; color: #666; }