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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    background: white;
    border-radius: 10px;
    padding: 30px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
}

h1 {
    color: #333;
    margin-bottom: 30px;
    text-align: center;
}

.add-todo {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

#newTodoInput {
    flex: 1;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 5px;
    font-size: 16px;
    transition: border-color 0.3s;
}

#newTodoInput:focus {
    outline: none;
    border-color: #667eea;
}

#addTodoBtn {
    padding: 12px 24px;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.3s;
}

#addTodoBtn:hover {
    background: #5568d3;
}

.todo-item {
    display: flex;
    align-items: center;
    padding: 15px;
    border: 1px solid #e0e0e0;
    border-radius: 5px;
    margin-bottom: 10px;
    transition: all 0.3s;
}

.todo-item:hover {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.todo-item.completed {
    background: #f5f5f5;
}

.todo-item input[type="checkbox"] {
    width: 20px;
    height: 20px;
    margin-right: 15px;
    cursor: pointer;
}

.todo-item .todo-text {
    flex: 1;
    font-size: 16px;
    color: #333;
}

.todo-item.completed .todo-text {
    text-decoration: line-through;
    color: #999;
}

.todo-item .delete-btn {
    padding: 8px 16px;
    background: #ff5252;
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 14px;
    cursor: pointer;
    transition: background 0.3s;
}

.todo-item .delete-btn:hover {
    background: #e04848;
}

#todoList:empty::before {
    content: "No todos yet. Add one above!";
    display: block;
    text-align: center;
    padding: 40px;
    color: #999;
    font-style: italic;
}