*{box-sizing:border-box}body{margin:0;font-family:system-ui,sans-serif;background:#f4f5f7;color:#202124}main{max-width:760px;margin:auto;padding:48px 20px}section{background:#fff;border:1px solid #ddd;border-radius:10px;padding:20px;margin-top:20px}.ok{color:#16733b}.error{color:#b3261e}form{display:flex;gap:8px}form input{flex:1;padding:10px;border:1px solid #bbb;border-radius:6px}button{padding:9px 14px;border:0;border-radius:6px;cursor:pointer}form button{background:#222;color:#fff}ul{list-style:none;padding:0}li{display:flex;justify-content:space-between;padding:10px 0;border-bottom:1px solid #eee}.done{text-decoration:line-through;color:#888}