body {
    font-family: sans-serif;
    background-color: #f4f4f4;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.container {
    background: #fff;
    padding: 20px;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    width: 400px;
}

h1 {
    text-align: center;
}

.input-container {
    display: flex;
    margin-bottom: 20px;
}

#task-input {
    flex: 1;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 3px;
}

#add-task-btn {
    padding: 10px;
    background: #007bff;
    color: #fff;
    border: none;
    border-radius: 3px;
    cursor: pointer;
}

#task-list {
    list-style: none;
    padding: 0;
}

#task-list li {
    background: #f9f9f9;
    padding: 10px;
    border-bottom: 1px solid #ddd;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#task-list li.completed {
    text-decoration: line-through;
    color: #888;
}

#task-list li button {
    background: #dc3545;
    color: #fff;
    border: none;
    padding: 5px 10px;
    border-radius: 3px;
    cursor: pointer;
}