/* ===== 全域樣式 ===== */
:root {
    /* 顏色系統 - 高對比度 */
    --color-primary: #2563eb;
    --color-primary-hover: #1e40af;
    --color-secondary: #64748b;
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;
    --color-background: #ffffff;
    --color-surface: #f8fafc;
    --color-text-primary: #0f172a;
    --color-text-secondary: #475569;
    --color-border: #e2e8f0;
    --color-focus: #3b82f6;
    
    /* 字體 */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft JhengHei", "PingFang TC", sans-serif;
    --font-size-base: 25px; /* 較大的基礎字體 */
    --font-size-lg: 25px;
    --font-size-xl: 28px;
    --font-size-2xl: 38px;
    
    /* 間距 */
    --spacing-xs: 12px;
    --spacing-sm: 19px;
    --spacing-md: 28px;
    --spacing-lg: 36px;
    --spacing-xl: 50px;
    
    /* 圓角 */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    
    /* 陰影 */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    
    /* 焦點環 */
    --focus-ring: 0 0 0 4px var(--color-focus);
}

/* 重置和基礎樣式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-background);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ===== 無障礙功能 ===== */

/* 跳過連結（鍵盤導航） */
.skip-link {
    position: absolute;
    top: -100px;
    left: 0;
    background: var(--color-primary);
    color: white;
    padding: var(--spacing-sm) var(--spacing-md);
    text-decoration: none;
    font-weight: bold;
    z-index: 100;
    border-radius: 0 0 var(--radius-sm) 0;
}

.skip-link:focus {
    top: 0;
    outline: 3px solid var(--color-focus);
    outline-offset: 2px;
}

/* 視覺隱藏但屏幕閱讀器可訪問 */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* 焦點指示器 */
*:focus {
    outline: 3px solid var(--color-focus);
    outline-offset: 2px;
}

*:focus:not(:focus-visible) {
    outline: none;
}

*:focus-visible {
    outline: 3px solid var(--color-focus);
    outline-offset: 2px;
}

/* ===== 佈局 ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

main {
    flex: 1;
    padding: var(--spacing-xl) 0;
}

/* ===== 標題 ===== */
header {
    background: linear-gradient(135deg, var(--color-primary) 0%, #1e40af 100%);
    color: white;
    padding: var(--spacing-lg) 0;
    box-shadow: var(--shadow-md);
}

header h1 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-sm);
    font-weight: 700;
}

header h1 .zh {
    display: block;
}

header h1 .en {
    display: block;
    font-size: var(--font-size-xl);
    opacity: 0.9;
    font-weight: 500;
}

/* ===== 雙語顯示 ===== */
.zh {
    display: block;
    margin-bottom: 4px;
}

.en {
    display: block;
    color: inherit;  /* 继承父元素颜色 */
    font-size: 0.9em;
    opacity: 0.95;
}

cssheader .en,
footer .en,
.btn-primary .en,
.btn-secondary .en,
.btn-back .en,
.btn-resource .en {
    color: rgba(255, 255, 255, 1);  /* 纯白色 */
}

/* ===== 按鈕樣式 ===== */
.btn-primary,
.btn-secondary,
.btn-back,
.btn-resource {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-lg);
    font-weight: 600;
    text-decoration: none;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.2s ease;
    min-height: 56px; /* 大觸摸目標 */
    min-width: 44px;
}

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

.btn-primary:hover,
.btn-primary:focus {
    background-color: var(--color-primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background-color: var(--color-surface);
    color: var(--color-text-primary);
    border: 2px solid var(--color-border);
}

.btn-secondary:hover,
.btn-secondary:focus {
    background-color: white;
    border-color: var(--color-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-back {
    background-color: rgba(255, 255, 255, 0.2);
    color: white;
    backdrop-filter: blur(10px);
}

.btn-back:hover,
.btn-back:focus {
    background-color: rgba(255, 255, 255, 0.3);
}

.btn-resource {
    background-color: var(--color-primary);
    color: white;
    width: 100%;
    margin-top: var(--spacing-sm);
}

.btn-resource:hover,
.btn-resource:focus {
    background-color: var(--color-primary-hover);
}

.btn-icon {
    font-size: 1.2em;
    font-weight: bold;
}

/* ===== 首頁樣式 ===== */
.hero {
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.hero h2 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-md);
    color: var(--color-primary);
}

.hero-text {
    font-size: var(--font-size-lg);
    max-width: 800px;
    margin: 0 auto var(--spacing-xl);
    line-height: 1.8;
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin: var(--spacing-xl) 0;
}

.feature-card {
    background: var(--color-surface);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-align: center;
    border: 2px solid var(--color-border);
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.feature-icon {
    font-size: 48px;
    margin-bottom: var(--spacing-sm);
}

.feature-card h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
    color: var(--color-primary);
}

.cta-container {
    margin-top: var(--spacing-xl);
}

.info-section {
    background: var(--color-surface);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    margin-top: var(--spacing-xl);
}

.info-section h2 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-md);
    color: var(--color-primary);
}

.info-section p {
    font-size: var(--font-size-lg);
    line-height: 1.8;
}

/* ===== 篩選器樣式 ===== */
.filter-section {
    background: var(--color-surface);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-xl);
    border: 2px solid var(--color-border);
}

.filter-controls {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    align-items: flex-end;
}

.filter-group {
    flex: 1;
    min-width: 200px;
}

.filter-group label {
    display: block;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    font-size: var(--font-size-lg);
}

.filter-select {
    width: 100%;
    padding: var(--spacing-sm);
    font-size: var(--font-size-lg);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-md);
    background-color: white;
    cursor: pointer;
    min-height: 56px;
}

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

/* ===== 學習資源卡片 ===== */
.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: var(--spacing-xl);  /* 增加间距 */
    margin-top: var(--spacing-lg);
}

.resource-card {
    background: white;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);  /* 增加内边距 */
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
}

.resource-card:hover,
.resource-card:focus {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.resource-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.resource-card h3 {
    font-size: var(--font-size-xl);
    flex: 1;
    color: var(--color-primary);
}

.level-badge {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    color: white;  /* 确保是白色 */
    font-size: 20px;  /* 增大字体 */
    font-weight: 700;  /* 加粗 */
    white-space: nowrap;
    min-width: 80px;
    text-align: center;
}

.level-badge .zh,
.level-badge .en {
    color: white !important;  /* 强制白色 */
    display: block;
    font-size: 20px;
}

.level-badge .en {
    font-size: 17px;
    margin-top: 2px;
}

.resource-body {
    display: flex;
    flex-direction: column;
    flex: 1;
}

.resource-description {
    margin-bottom: var(--spacing-md);
    line-height: 1.7;
    flex: 1;
}

/* ===== 載入和錯誤狀態 ===== */
.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xl);
    gap: var(--spacing-md);
}

.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.error-message {
    background: #fef2f2;
    border: 2px solid var(--color-danger);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    text-align: center;
}

.error-message h3 {
    color: var(--color-danger);
    margin-bottom: var(--spacing-sm);
}

.no-results {
    text-align: center;
    padding: var(--spacing-xl);
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    border: 2px dashed var(--color-border);
}

/* ===== 頁尾 ===== */
footer {
    background-color: var(--color-text-primary);
    color: white;
    padding: var(--spacing-lg) 0;
    margin-top: auto;
    text-align: center;
}

/* ===== 響應式設計 ===== */
@media (max-width: 768px) {
    :root {
        --font-size-base: 16px;
        --font-size-lg: 18px;
        --font-size-xl: 22px;
        --font-size-2xl: 28px;
    }
    
    .features {
        grid-template-columns: 1fr;
    }
    
    .resources-grid {
        grid-template-columns: 1fr;
    }
    
    .filter-controls {
        flex-direction: column;
        align-items: stretch;
    }
    
    .filter-group {
        width: 100%;
    }
}

/* ===== 打印樣式 ===== */
@media print {
    header,
    footer,
    .btn-primary,
    .btn-secondary,
    .btn-back,
    .filter-section {
        display: none;
    }
    
    .resource-card {
        break-inside: avoid;
    }
}

/* ===== 高對比度模式支持 ===== */
@media (prefers-contrast: high) {
    :root {
        --color-primary: #0047ab;
        --color-text-primary: #000000;
        --color-border: #000000;
    }
    
    .btn-primary,
    .btn-secondary,
    .resource-card {
        border-width: 3px;
    }
}

/* ===== 減少動畫（尊重用戶偏好） ===== */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* ==========================================
   Header 内的按钮（不随页面滚动）
   ========================================== */

/* 给 header 添加相对定位 */
header {
    position: relative !important;
}

/* Header 内容布局 */
.header-wrapper {
    display: flex !important;
    justify-content: space-between !important;
    align-items: center !important;
    gap: 24px !important;
    position: relative !important;
}

/* 按钮样式 - 绝对定位在 header 右上角 */
.btn-extension-header {
    /* 绝对定位（相对于 header） */
    position: absolute !important;
    top: 50% !important;
    right: 24px !important;
    transform: translateY(-50%) !important;
    z-index: 100 !important;
    
    /* 布局 */
    display: flex !important;
    flex-direction: column !important;
    align-items: center !important;
    justify-content: center !important;
    gap: 8px !important;
    
    /* 尺寸 */
    width: 160px !important;
    height: 110px !important;
    padding: 20px 24px !important;
    margin: 0 !important;
    
    /* 白底蓝字 */
    background: white !important;
    color: #2563eb !important;
    border: 3px solid white !important;
    border-radius: 12px !important;
    
    /* 阴影 */
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15) !important;
    
    /* 其他 */
    text-decoration: none !important;
    text-align: center !important;
    cursor: pointer !important;
    transition: all 0.3s ease !important;
}

/* 悬停效果 */
.btn-extension-header:hover,
.btn-extension-header:focus {
    background: rgba(255, 255, 255, 0.95) !important;
    transform: translateY(-50%) scale(1.05) !important;
    box-shadow: 0 6px 24px rgba(0, 0, 0, 0.25) !important;
    border-color: white !important;
}

/* 图标 */
.btn-extension-header .extension-icon {
    font-size: 32px !important;
    line-height: 1 !important;
    display: block !important;
}

/* 文字容器 */
.btn-extension-header .extension-text {
    display: flex !important;
    flex-direction: column !important;
    align-items: center !important;
    gap: 2px !important;
}

/* 中文 */
.btn-extension-header .zh {
    font-size: 16px !important;
    font-weight: 700 !important;
    color: #2563eb !important;
    display: block !important;
    line-height: 1.2 !important;
}

/* 英文 */
.btn-extension-header .en {
    font-size: 13px !important;
    font-weight: 600 !important;
    color: #1e40af !important;
    display: block !important;
    line-height: 1.2 !important;
}

/* 悬停时文字保持蓝色 */
.btn-extension-header:hover .zh,
.btn-extension-header:focus .zh {
    color: #1e40af !important;
}

.btn-extension-header:hover .en,
.btn-extension-header:focus .en {
    color: #1e40af !important;
}

/* 给标题留出空间 */
.header-wrapper h1 {
    flex: 1 !important;
    margin-right: 180px !important;
    margin-bottom: 0 !important;
}

/* 响应式 - 平板 */
@media (max-width: 1024px) {
    .btn-extension-header {
        right: 16px !important;
        width: 140px !important;
        height: 80px !important;
        padding: 14px 16px !important;
    }
    
    .btn-extension-header .extension-icon {
        font-size: 28px !important;
    }
    
    .btn-extension-header .zh {
        font-size: 15px !important;
    }
    
    .btn-extension-header .en {
        font-size: 12px !important;
    }
    
    .header-wrapper h1 {
        margin-right: 160px !important;
    }
}

/* 响应式 - 手机 */
@media (max-width: 768px) {
    .header-wrapper {
        flex-direction: column !important;
        align-items: stretch !important;
        gap: 16px !important;
    }
    
    .btn-extension-header {
        position: relative !important;
        top: auto !important;
        right: auto !important;
        transform: none !important;
        width: 100% !important;
        height: 80px !important;
        margin: 0 auto !important;
        max-width: 300px !important;
    }
    
    .btn-extension-header:hover,
    .btn-extension-header:focus {
        transform: scale(1.02) !important;
    }
    
    .header-wrapper h1 {
        margin-right: 0 !important;
        text-align: center !important;
    }
}

/* 删除旧的固定按钮样式冲突 */
.btn-extension-fixed {
    display: none !important;
}