body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    padding-top: 50px;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

#app {
    width: 90%;
    max-width: 500px;
    margin: auto;
    padding: 20px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

input, button {
    width: 100%;
    padding: 10px;
    margin: 5px 0;
    box-sizing: border-box;
}

button {
    cursor: pointer;
    background-color: #007bff;
    color: white;
    border: none;
}

button:hover {
    background-color: #0056b3;
}

.task-item {
    margin: 10px 0;
    padding: 10px;
    background-color: #f9f9f9;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-radius: 5px;
}

.task-item.completed {
    text-decoration: line-through;
    background-color: #e9ecef;
}

@media (max-width: 768px) {
    body {
        padding-top: 20px;
    }
}