* {
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
}

body {
    background-color: #f2f2f2;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.todo-app {
    background-color: #ffffff;
    width: 360px;
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}

h1 {
    text-align: center;
    margin-bottom: 15px;
}

.input-section {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

#taskInput {
    flex: 1;
    padding: 10px;
    font-size: 16px;
}

#addTask {
    padding: 10px 15px;
    background-color: #007aff;
    color: #ffffff;
    border: none;
    border-radius: 6px;
    cursor: pointer;
}

#addTask:hover {
    background-color: #005fd1;
}

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

#taskList li {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px;
    margin-bottom: 8px;
    background-color: #f9f9f9;
    border-radius: 6px;
}

#taskList li.completed {
    text-decoration: line-through;
    color: #999999;
}