body{font-family:sans-serif;background:#f5f5f5;margin:0}.container{max-width:700px;margin:2rem auto;padding:1rem}h1{margin-bottom:1rem}button{padding:.5rem 1.2rem;font-size:1rem;cursor:pointer}ul{list-style:none;padding:0;margin-top:1.5rem}li{background:#fff;border:1px solid #ddd;border-radius:6px;margin-bottom:.5rem;overflow:hidden}.aufgabe-titel{width:100%;text-align:left;background:none;border:none;padding:.8rem 1rem;font-size:1rem;font-weight:700;cursor:pointer}.aufgabe-titel:hover{background:#f0f0f0}.aufgabe-detail{padding:.5rem 1rem 1rem;border-top:1px solid #eee}.fehler{color:red}