body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;background-color:#f4f4f9;color:#333;margin:0;padding:50px 0 0;display:flex;justify-content:center;align-items:flex-start;min-height:100vh}.app-container{width:100%;max-width:500px;margin:0 auto;background:#fff;border-radius:8px;box-shadow:0 4px 6px #0000001a;padding:20px 30px}header h1{text-align:center;color:#4a4a4a;font-size:2.5em;margin:0 0 20px}form{display:flex;margin-bottom:20px}form input[type=text]{flex-grow:1;border:2px solid #ddd;border-radius:4px;padding:10px 15px;font-size:1em;outline:none;transition:border-color .2s}form input[type=text]:focus{border-color:#7b68ee}form button{background-color:#7b68ee;color:#fff;border:none;padding:10px 20px;border-radius:4px;margin-left:10px;cursor:pointer;font-size:1em;transition:background-color .2s}form button:hover{background-color:#6a5acd}ul{list-style:none;padding:0;margin:0}li{display:flex;align-items:center;padding:15px 5px;border-bottom:1px solid #eee;transition:background-color .2s}li:last-child{border-bottom:none}li.completed span{text-decoration:line-through;color:#aaa}li input[type=checkbox]{margin-right:15px;width:20px;height:20px;cursor:pointer}li span{flex-grow:1;font-size:1.1em}li button{background:#ff4d4d;color:#fff;border:none;border-radius:4px;padding:5px 10px;cursor:pointer;opacity:0;transition:opacity .2s}li:hover button{opacity:1}
