body{
    margin:0;
    font-family:Arial, sans-serif;
    background:#202124;
    color:white;
    display:flex;
    justify-content:center;
    padding-top:50px;
}

.container{
    width:400px;
}

.input-area{
    display:flex;
    gap:10px;
}

input{
    flex:1;
    padding:10px;
}

button{
    padding:10px 20px;
    cursor:pointer;
}

ul{
    list-style:none;
    padding:0;
}

li{
    display:flex;
    justify-content:space-between;
    align-items:center;
    background:#333;
    margin-top:10px;
    padding:10px;
    border-radius:8px;
}

.completed{
    text-decoration:line-through;
    color:gray;
}