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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: #f5f5f5;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 500px;
}

.todo-app {
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

.todo-header {
    background: #333;
    color: white;
    padding: 20px;
    text-align: center;
}

.todo-header h1 {
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 5px;
}

.subtitle {
    font-size: 0.9rem;
    opacity: 0.8;
}

.todo-input-container {
    display: flex;
    gap: 10px;
    padding: 20px;
    border-bottom: 1px solid #eee;
}

.todo-input {
    flex: 1;
    padding: 10px 15px;
    font-size: 16px;
    border: 1px solid #ddd;
    border-radius: 4px;
    outline: none;
}

.todo-input:focus {
    border-color: #333;
}

.add-btn {
    padding: 10px 20px;
    background: #333;
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 16px;
    cursor: pointer;
}

.add-btn:hover {
    background: #555;
}

#btnAll:hover{
    background: #555;
}

.filter-container {
    display: flex;
    justify-content: center;
    gap: 10px;
    padding: 15px;
    background: #fafafa;
}

.filter-btn {
    padding: 6px 16px;
    border: 1px solid #ddd;
    background: white;
    border-radius: 4px;
    font-size: 14px;
    cursor: pointer;
}

.filter-btn:hover {
    background: #f5f5f5;
}

.filter-btn.active {
    background: #333;
    color: white;
    border-color: #333;
}

.todo-list {
    list-style: none;
    max-height: 400px;
    overflow-y: auto;
}

.todo-item {
    display: flex;
    align-items: center;
    padding: 15px 20px;
    border-bottom: 1px solid #eee;
}

.todo-item:hover {
    background-color: #fafafa;
}

.todo-item.completed {
    opacity: 0.6;
}

.todo-checkbox {
    width: 18px;
    height: 18px;
    margin-right: 12px;
    cursor: pointer;
}

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

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

.delete-btn {
    width: 28px;
    height: 28px;
    background: transparent;
    color: #999;
    border: none;
    border-radius: 4px;
    font-size: 24px;
    line-height: 1;
    cursor: pointer;
    opacity: 0;
    display: flex;
    align-items: center;
    justify-content: center;
}

.todo-item:hover .delete-btn {
    opacity: 1;
}

.delete-btn:hover {
    background: #f5f5f5;
    color: #333;
}

.todo-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    background: #fafafa;
    border-top: 1px solid #eee;
}

.items-left {
    color: #666;
    font-size: 14px;
}

.clear-completed {
    padding: 6px 12px;
    background: transparent;
    color: #666;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 14px;
    cursor: pointer;
}

.clear-completed:hover {
    background: #f5f5f5;
}

/* Scrollbar styling */
.todo-list::-webkit-scrollbar {
    width: 6px;
}

.todo-list::-webkit-scrollbar-track {
    background: #f1f1f1;
}

.todo-list::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 3px;
}

.todo-list::-webkit-scrollbar-thumb:hover {
    background: #999;
}

/* Responsive design */
@media (max-width: 600px) {
    .todo-header h1 {
        font-size: 2rem;
    }
    
    .todo-input-container {
        flex-direction: column;
    }
    
    .add-btn {
        width: 100%;
        justify-content: center;
    }
    
    .filter-container {
        flex-wrap: wrap;
    }
    
    .todo-item {
        padding: 15px 20px;
    }
}