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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 600px;
    margin: 40px auto;
    padding: 20px;
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

h1 {
    text-align: center;
    margin-bottom: 30px;
    color: #4a4a4a;
}

.todo-form {
    display: flex;
    margin-bottom: 20px;
}

#todoInput {
    flex: 1;
    padding: 12px 15px;
    border: 2px solid #ddd;
    border-radius: 4px 0 0 4px;
    font-size: 16px;
    outline: none;
    transition: border-color 0.3s;
}

#todoInput:focus {
    border-color: #4caf50;
}

#addBtn {
    padding: 12px 20px;
    background-color: #4caf50;
    color: white;
    border: none;
    border-radius: 0 4px 4px 0;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s;
}

#addBtn:hover {
    background-color: #45a049;
}

.todo-list {
    list-style-type: none;
}

.todo-item {
    display: flex;
    align-items: center;
    padding: 15px;
    border-bottom: 1px solid #eee;
    animation: fadeIn 0.3s ease-in;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.todo-text {
    flex: 1;
    margin-left: 10px;
    font-size: 16px;
    transition: text-decoration 0.3s, color 0.3s;
}

.completed .todo-text {
    text-decoration: line-through;
    color: #888;
}

.complete-btn {
    background-color: #2196F3;
    color: white;
    border: none;
    padding: 8px 12px;
    border-radius: 4px;
    cursor: pointer;
    margin-right: 8px;
    transition: background-color 0.3s;
}

.complete-btn:hover {
    background-color: #0b7dda;
}

.delete-btn {
    background-color: #f44336;
    color: white;
    border: none;
    padding: 8px 12px;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.delete-btn:hover {
    background-color: #d32f2f;
}

.empty-message {
    text-align: center;
    color: #888;
    font-style: italic;
    padding: 20px;
}

@media (max-width: 600px) {
    .container {
        margin: 20px 10px;
        padding: 15px;
    }
    
    .todo-form {
        flex-direction: column;
    }
    
    #todoInput {
        border-radius: 4px;
        margin-bottom: 10px;
    }
    
    #addBtn {
        border-radius: 4px;
        width: 100%;
    }
}