body{background:#f9f9f9;margin:0;padding:0;font-family:sans-serif}.app-container{max-width:800px;margin:0 auto;padding:20px}.event-card{background:#fff;border:1px solid #ddd;border-radius:10px;margin-bottom:20px;padding:20px;box-shadow:0 2px 4px #0000000d}button{cursor:pointer;color:#fff;background:#007bff;border:none;border-radius:5px;padding:10px 18px}button:hover{background:#0056b3}form{flex-direction:column;gap:10px;max-width:400px;margin-bottom:30px;display:flex}input,textarea{border:1px solid #ccc;border-radius:4px;padding:8px}header{border-bottom:2px solid #ddd;margin-bottom:20px;padding-bottom:10px}@media (width<=768px){.event-card{box-sizing:border-box;width:100%}}