* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}

#todo-app {
    width: 500px;
    margin: 0 auto;
    text-align: center;
}

h1 {
    margin: 15px 0;
}

#add-todo-form {
    margin-bottom: 15px;
}

#add-todo-form input {
    width: 60%;
    padding: 12px 20px;
    margin: 8px 0;
    border: 2px solid #ccc;
    border-radius: 4px;
}

#add-todo-form button {
    width: 20%;
    background-color: #4caf50;
    color: white;
    padding: 14px 20px;
    margin: 8px 0;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

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

#todo-list li {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #f1f1f1;
    padding: 12px;
    margin-bottom: 8px;
}

#todo-list li .delete-button {
    background-color: #ff0000;
    color: white;
    border: none;
    padding: 8px;
    cursor: pointer;
    float: right;
}

.done {
    text-decoration: line-through;
}

.todo-item.completed {
    text-decoration: line-through;
    color: green;
}

.todo-item .action-buttons button {
    margin-left: 10px;
}

.todo-item .action-buttons .done-button {
    background-color: green;
    color: white;
    border: none;
    padding: 8px;
    cursor: pointer;
}