body{font-family:system-ui,sans-serif;max-width:860px;margin:auto;padding:1rem;line-height:1.6;color:#222}header{display:flex;justify-content:space-between;flex-wrap:wrap;border-bottom:1px solid #ddd;padding-bottom:.5rem}nav a{margin-left:1rem}.logo{font-weight:700;text-decoration:none;color:#000}.box{background:#f5f5f5;padding:1rem;border-radius:8px}footer{border-top:1px solid #ddd;margin-top:2rem;font-size:.9rem;color:#666}input,textarea{width:100%;padding:.5rem;margin:.25rem 0}button{padding:.5rem 1rem}