* {
    box-sizing: border-box;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    max-width: 800px;
    margin: 40px auto;
    padding: 0 20px;
    background: #f5f5f5;
}
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}
h1 {
    color: #333;
    margin: 0;
}
.user-info {
    display: flex;
    align-items: center;
    gap: 10px;
    color: #666;
}
.logout-btn {
    padding: 8px 16px;
    font-size: 14px;
    background: #6c757d;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}
.logout-btn:hover {
    background: #545b62;
}
.add-form {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}
.add-form input[type="text"] {
    flex: 1;
    padding: 12px;
    font-size: 16px;
    border: 1px solid #ddd;
    border-radius: 4px;
}
.add-form button {
    padding: 12px 24px;
    font-size: 16px;
    background: #007bff;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}
.add-form button:hover {
    background: #0056b3;
}
.todo-list {
    list-style: none;
    padding: 0;
}
.todo-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 15px;
    background: white;
    border-radius: 4px;
    margin-bottom: 10px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}
.todo-item.completed .todo-title {
    text-decoration: line-through;
    color: #888;
}
.todo-title {
    flex: 1;
    font-size: 16px;
}
.btn {
    padding: 8px 16px;
    font-size: 14px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}
.btn-toggle {
    background: #28a745;
    color: white;
}
.btn-toggle:hover {
    background: #1e7e34;
}
.todo-item.completed .btn-toggle {
    background: #6c757d;
}
.todo-item.completed .btn-toggle:hover {
    background: #545b62;
}
.btn-delete {
    background: #dc3545;
    color: white;
}
.btn-delete:hover {
    background: #c82333;
}
.empty-message {
    text-align: center;
    color: #666;
    padding: 40px;
}