body{margin:0;font-family:Arial,sans-serif;background:#eef3fb}.app{max-width:1000px;margin:auto;padding:20px}h1{text-align:center;color:#07f}.subtitle{text-align:center;margin-bottom:20px;color:#555}.nav{display:flex;justify-content:center;gap:10px;margin-bottom:25px}.nav button{padding:10px 16px;border:none;border-radius:8px;cursor:pointer;background:#dbe7ff;font-weight:700;transition:.2s}.nav button:hover{background:#07f;color:#fff}.section h2{border-left:5px solid #0077ff;padding-left:10px;margin:20px 0}.card{background:#fff;padding:16px;border-radius:12px;margin-bottom:15px;box-shadow:0 4px 10px #00000014}.question{font-weight:700}.answer{margin-top:6px}.example{margin-top:8px;background:#f5f7ff;padding:8px;border-radius:6px;font-size:14px}.card a{text-decoration:none;color:#07f;font-weight:700}.card a:hover{text-decoration:underline}.footer{margin-top:40px;padding:25px;background:#f7f7f7;border-radius:12px;text-align:center}.footer a{color:#07f;font-weight:700;text-decoration:none}.footer a:hover{text-decoration:underline}.footer-card{margin-top:15px;background:#fff;padding:18px;border-radius:10px;box-shadow:0 3px 8px #00000014}.footer h2{margin-bottom:8px}@media(max-width:600px){.footer{padding:15px}.footer-card{padding:14px}}@media(max-width:768px){.app{padding:12px}.nav{flex-direction:column}.card{padding:12px}}