index.css

body {
    font-family: Arial, sans-serif;
    background-color: #f0f0f0;
    padding: 20px;
}

.todo-list {
    width: 300px;
    margin: 0 auto;
    background-color: #fff;
    padding: 20px;
    border-radius: 4px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

.todo-list h1 {
    text-align: center;
    color: #333;
}

.add-todo {
    display: flex;
    justify-content: space-between;
    margin-bottom: 20px;
}

.add-todo input[type="text"] {
    flex-grow: 1;
    padding: 5px;
    margin-right: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

button {
    padding: 5px 10px;
    background-color: #007BFF;
    color: #fff;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

.todo-list ul {
    padding: 0;
    list-style-type: none;
}

.todo-list li {
    display: flex;
    align-items: center;
    margin-bottom: 10px;
}

.todo-list li input[type="checkbox"] {
    margin-right: 10px;
}

.todo-list li label {
    flex-grow: 1;
}