/* 待辦事項應用樣式 */
:root {
    --primary-color: #4c51bf;
    --secondary-color: #805ad5;
    --success-color: #48bb78;
    --danger-color: #f56565;
    --gray-100: #f7fafc;
    --gray-200: #edf2f7;
    --gray-300: #e2e8f0;
    --gray-400: #cbd5e0;
    --gray-500: #a0aec0;
    --gray-600: #718096;
    --gray-700: #4a5568;
    --gray-800: #2d3748;
    --gray-900: #1a202c;
}

* {
    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;
    color: var(--gray-800);
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: 12px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

header {
    background: var(--primary-color);
    color: white;
    padding: 30px;
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

.subtitle {
    opacity: 0.9;
    font-size: 1.1rem;
}

/* 輸入區域 */
.todo-input-section {
    display: flex;
    gap: 10px;
    padding: 30px;
    background: var(--gray-100);
    border-bottom: 1px solid var(--gray-300);
}

#todoInput {
    flex: 1;
    padding: 12px 16px;
    font-size: 16px;
    border: 2px solid var(--gray-300);
    border-radius: 6px;
    transition: border-color 0.3s;
}

#todoInput:focus {
    outline: none;
    border-color: var(--primary-color);
}

.btn {
    padding: 12px 24px;
    font-size: 16px;
    font-weight: 600;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: var(--secondary-color);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(76, 81, 191, 0.3);
}

/* 過濾器 */
.todo-filters {
    display: flex;
    gap: 10px;
    padding: 20px 30px;
    background: var(--gray-50);
    border-bottom: 1px solid var(--gray-200);
}

.filter-btn {
    padding: 8px 16px;
    background: transparent;
    border: 2px solid var(--gray-300);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s;
}

.filter-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.filter-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* 統計資訊 */
.todo-stats {
    display: flex;
    justify-content: space-around;
    padding: 20px 30px;
    background: var(--gray-50);
    border-bottom: 2px solid var(--gray-200);
}

.stat-item {
    text-align: center;
}

.stat-label {
    color: var(--gray-600);
    font-size: 0.9rem;
}

.stat-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-top: 5px;
}

/* 待辦事項列表 */
.todo-list {
    list-style: none;
    padding: 20px 30px;
    min-height: 200px;
}

.todo-item {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 15px;
    margin-bottom: 10px;
    background: var(--gray-50);
    border-radius: 8px;
    transition: all 0.3s;
}

.todo-item:hover {
    transform: translateX(5px);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

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

.todo-item.completed .todo-text {
    text-decoration: line-through;
    color: var(--gray-500);
}

.todo-checkbox {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

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

.delete-btn {
    padding: 6px 12px;
    background: var(--danger-color);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.3s;
}

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

.delete-btn:hover {
    background: #e53e3e;
}

.empty-state {
    text-align: center;
    padding: 40px;
    color: var(--gray-500);
    font-style: italic;
}

/* 資訊區塊 */
.info-section {
    padding: 30px;
    background: var(--gray-100);
    border-top: 2px solid var(--gray-200);
}

.info-section h2 {
    color: var(--gray-800);
    margin-bottom: 15px;
}

.info-section p {
    color: var(--gray-600);
    line-height: 1.6;
    margin-bottom: 20px;
}

.feature-request {
    background: white;
    padding: 20px;
    border-radius: 8px;
    border: 2px solid var(--gray-200);
}

.feature-request h3 {
    color: var(--gray-700);
    margin-bottom: 15px;
    font-size: 1.1rem;
}

.feature-request ul {
    list-style: none;
    padding-left: 0;
}

.feature-request li {
    padding: 8px 0;
    color: var(--gray-600);
    border-bottom: 1px solid var(--gray-200);
}

.feature-request li:last-child {
    border-bottom: none;
}

.feature-request li::before {
    content: "→ ";
    color: var(--primary-color);
    font-weight: bold;
    margin-right: 8px;
}

/* 響應式設計 */
@media (max-width: 640px) {
    body {
        padding: 10px;
    }
    
    header {
        padding: 20px;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .todo-input-section,
    .todo-filters,
    .todo-list,
    .info-section {
        padding: 15px;
    }
    
    .todo-stats {
        padding: 15px;
        font-size: 0.9rem;
    }
    
    .stat-value {
        font-size: 1.2rem;
    }
}