body {
    font-family: Arial, sans-serif;
    background-color: #f5f5f5;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

h1 {
    color: #2c3e50;
    margin-bottom: 20px;
}

#todo-input {
    padding: 10px 15px;
    border: 1px solid #bdc3c7;
    border-radius: 5px;
    outline: none;
    width: 300px;
}

#add-btn {
    background-color: #3498db;
    color: #ffffff;
    padding: 10px 15px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    margin-left: 10px;
    outline: none;
    transition: background-color 0.3s;
}

#add-btn:hover {
    background-color: #2980b9;
}

#todo-list {
    list-style-type: none;
    padding: 0;
    margin: 20px 0;
}

li {
    background-color: #ffffff;
    padding: 10px 15px;
    border: 1px solid #bdc3c7;
    border-radius: 5px;
    margin-bottom: 10px;
    cursor: pointer;
    transition: background-color 0.3s;
}

li:hover {
    background-color: #ecf0f1;
}

.completed {
    text-decoration: line-through;
    color: #95a5a6;
}