/**
 * 文章導航 - 完整樣式表(修正版)
 * Version: 5.1.1
 * 修正: 1.上下圖滿版置中一致 2.增加堆疊模式
 */

/* ========================================
   CSS 變數定義
======================================== */
:root {
    /* 圖片尺寸(由 PHP 動態設定) */
    --post-nav-side-img-width: 200px;
    --post-nav-side-img-height: 150px;
    --post-nav-top-img-ratio: 16 / 9;
    --post-nav-img-fit: cover;
    --post-nav-title-lines: 3;
    --nav-border-radius: 12px;
    --nav-shadow: 0 4px 12px rgba(0,0,0,0.1);
    --nav-hover-effect: zoom;
    
    /* 顏色系統 - 亮色模式(預設) */
    --nav-primary: #2563eb;
    --nav-primary-hover: #1d4ed8;
    --nav-text: #111827;
    --nav-text-secondary: #4b5563;
    --nav-text-light: #6b7280;
    --nav-bg: #ffffff;
    --nav-bg-hover: #f9fafb;
    --nav-border: #e5e7eb;
    --nav-overlay: rgba(0, 0, 0, 0.75);
    
    /* 間距 */
    --nav-spacing-xs: 4px;
    --nav-spacing-sm: 8px;
    --nav-spacing-md: 16px;
    --nav-spacing-lg: 24px;
    --nav-spacing-xl: 32px;
    
    /* 動畫 */
    --nav-transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --nav-transition-fast: all 0.2s ease;
}

/* 深色模式變數 */
body.dark-mode {
    --nav-text: #f9fafb;
    --nav-text-secondary: #d1d5db;
    --nav-text-light: #9ca3af;
    --nav-bg: #1f2937;
    --nav-bg-hover: #111827;
    --nav-border: #374151;
    --nav-overlay: rgba(0, 0, 0, 0.85);

    /* --- ▼▼▼ 以下為新增的通用深色模式樣式 ▼▼▼ --- */
    
    /* 設定頁面背景和文字顏色 */
    background-color: #181a1b; /* 深色背景 */
    color: #e8e6e3; /* 淺色文字 */
    
    /* 確保您的文章內容區域也應用這些顏色 */
    /* 注意：您可能需要根據您的佈景主題修改下面的選擇器，例如 .entry-content 或 #main */
    .site-content, 
    .entry-content,
    .post-content {
         background-color: transparent; /* 繼承 body 的背景色 */
         color: inherit; /* 繼承 body 的文字顏色 */
    }
    
    /* 通用連結顏色 */
    a {
        color: #8ab4f8;
    }

    a:hover {
        color: #a3c5fb;
    }
    
    /* 標題顏色 */
    h1, h2, h3, h4, h5, h6 {
        color: #f1f1f1;
    }

    /* --- ▲▲▲ 以上為新增的通用深色模式樣式 ▲▲▲ --- */
}
/* ========================================
   深色模式切換按鈕
======================================== */
.dark-mode-toggle {
    position: fixed;
    bottom: 24px;
    right: 24px;
    width: 56px;
    height: 56px;
    background: var(--nav-primary);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--nav-transition);
}

.dark-mode-toggle:hover {
    transform: scale(1.1);
    box-shadow: 0 6px 20px rgba(0,0,0,0.25);
}

.dark-mode-toggle:active {
    transform: scale(0.95);
}

.dark-mode-toggle svg {
    width: 24px;
    height: 24px;
    color: white;
    transition: var(--nav-transition);
}

.dark-mode-toggle .icon-sun {
    display: none;
}

.dark-mode-toggle .icon-moon {
    display: block;
}

body.dark-mode .dark-mode-toggle .icon-sun {
    display: block;
}

body.dark-mode .dark-mode-toggle .icon-moon {
    display: none;
}

@media (max-width: 768px) {
    .dark-mode-toggle {
        width: 48px;
        height: 48px;
        bottom: 16px;
        right: 16px;
    }
    
    .dark-mode-toggle svg {
        width: 20px;
        height: 20px;
    }
}

/* ========================================
   基礎佈局
======================================== */
/**
 * 修正：無論單篇或雙篇，都使用 Flexbox 佈局以確保對齊正確
 */
.post-navigation {
    display: flex;
    justify-content: space-between; /* 保持 space-between，這對單個元素對齊很關鍵 */
    flex-wrap: wrap; /* 增加 wrap 以處理手機端堆疊的情況 */
    gap: var(--nav-spacing-lg); /* 將 gap 移到這裡統一管理 */
}

/* ========== 新增箭頭導航模式 ========== */
.nav-mode-arrow {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--nav-spacing-lg);
    padding: var(--nav-spacing-lg) 0;
}

.nav-arrow {
    display: flex;
    align-items: center;
    gap: var(--nav-spacing-sm);
    padding: 12px 24px;
    background: var(--nav-bg);
    border: 2px solid var(--nav-border);
    border-radius: 50px;
    color: var(--nav-text);
    text-decoration: none;
    font-weight: 600;
    font-size: 14px;
    transition: var(--nav-transition);
    cursor: pointer;
}

.nav-arrow:hover {
    background: var(--nav-primary);
    border-color: var(--nav-primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.nav-arrow svg {
    width: 20px;
    height: 20px;
    transition: var(--nav-transition);
}

.nav-arrow:hover svg {
    color: white;
}

.nav-arrow-prev:hover svg {
    transform: translateX(-3px);
}

.nav-arrow-next:hover svg {
    transform: translateX(3px);
}

.nav-arrow-disabled {
    width: 48px;
    height: 48px;
    opacity: 0;
    pointer-events: none;
}

/* 中間導航按鈕 */
.nav-center-button {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--nav-spacing-sm);
    padding: 12px 24px;
    background: var(--nav-primary);
    border: 2px solid var(--nav-primary);
    border-radius: 50px;
    color: white;
    text-decoration: none;
    font-weight: 600;
    font-size: 14px;
    transition: var(--nav-transition);
    cursor: pointer;
}

/* 中間導航按鈕 - 只顯示圖示模式 */
.nav-center-button.icon-only {
    padding: 12px;
    border-radius: 50%;
    width: 48px;
    height: 48px;
}

.nav-center-button.icon-only svg {
    margin: 0;
}

/* 箭頭模式 - 只顯示圖示 */
.nav-mode-arrow .nav-center-button.icon-only {
    width: 48px;
    height: 48px;
}

/* 完整模式 - 只顯示圖示 */
.nav-center-full.icon-only {
    padding: 12px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
}

.nav-center-full.icon-only svg {
    margin: 0;
}

/* 手機版調整 */
@media (max-width: 768px) {
    /* 有文字模式在手機版隱藏文字 - 已移除，改為顯示 */
    /* .nav-center-button.has-text .nav-center-text,
    .nav-center-full.has-text span {
        display: none;
    } */
    
    /* 有文字模式在手機版變成圓形 */
    .nav-center-button.has-text {
        padding: 10px;
        width: 44px;
        height: 44px;
        border-radius: 50%;
    }
    
    .nav-center-full.has-text {
        padding: 10px;
        width: 44px;
        height: 44px;
        border-radius: 50%;
    }
    
    /* 只顯示圖示模式 */
    .nav-center-button.icon-only {
        width: 44px;
        height: 44px;
        padding: 10px;
    }
    
    .nav-center-full.icon-only {
        width: 44px;
        height: 44px;
        padding: 10px;
    }
}

@media (max-width: 480px) {
    .nav-center-button.icon-only,
    .nav-center-full.icon-only,
    .nav-center-button.has-text,
    .nav-center-full.has-text {
        width: 40px;
        height: 40px;
        padding: 8px;
    }
}

.nav-center-button:hover {
    background: var(--nav-primary-hover);
    border-color: var(--nav-primary-hover);
    transform: translateY(-2px) scale(1.05);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

.nav-center-button svg {
    width: 20px;
    height: 20px;
    color: white;
}

.nav-center-text {
    color: white;
}


/* 中間導航按鈕 - 完整模式專用 */
.nav-mode-default.has-center-button {
    position: relative;
    padding-bottom: 60px; /* 增加底部間距以容納按鈕 */
}

.nav-center-full {
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    align-items: center;
    gap: var(--nav-spacing-sm);
    padding: 10px 20px;
    background: var(--nav-primary);
    border: 3px solid var(--nav-bg);
    border-radius: 50px;
    color: white;
    text-decoration: none;
    font-weight: 600;
    font-size: 13px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    transition: var(--nav-transition);
    z-index: 10;
}

.nav-center-full:hover {
    background: var(--nav-primary-hover);
    transform: translateX(-50%) translateY(-4px) scale(1.05);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

.nav-center-full svg {
    width: 18px;
    height: 18px;
    color: white;
}

.nav-center-full span {
    color: white;
}

/* 手機版 */
@media (max-width: 768px) {
    .nav-center-full {
        padding: 8px 16px;
        font-size: 12px;
        /* 確保在手機版也能正確定位 */
        bottom: 10px; 
        width: auto;
        white-space: nowrap;
    }
    
    .nav-center-full svg {
        width: 16px;
        height: 16px;
    }
    
    .nav-center-full span {
        display: inline-block; /* 手機版顯示文字 */
        margin-left: 4px;
    }

    /* Mobile Stack Mode Center Button Alignment */
    .post-navigation.mobile-stack .nav-center-full {
        position: static;
        transform: none;
        margin: 10px auto !important; /* Force centering */
        align-self: center;
        order: 2;
        display: inline-flex;
        width: fit-content; /* Ensure width fits content */
        left: auto;
        right: auto;
    }
    
    .post-navigation.mobile-stack.has-center-button {
        padding-bottom: 0;
        display: flex;
        flex-direction: column;
    }

    .post-navigation.mobile-stack .nav-previous {
        order: 1;
    }

    .post-navigation.mobile-stack .nav-next {
        order: 3;
    }
}

/* ========================================
   簡單導航模式 (Simple Mode)
======================================== */
.nav-mode-simple {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--nav-spacing-md);
    padding: var(--nav-spacing-lg) 0;
    border-top: 1px solid var(--nav-border);
    border-bottom: 1px solid var(--nav-border);
}

.nav-mode-simple .nav-simple-prev,
.nav-mode-simple .nav-simple-next {
    flex: 1;
    display: flex;
}

.nav-mode-simple .nav-simple-prev {
    justify-content: flex-start;
}

.nav-mode-simple .nav-simple-next {
    justify-content: flex-end;
}

.nav-mode-simple .nav-simple-link {
    display: flex;
    align-items: center;
    gap: var(--nav-spacing-sm);
    padding: 10px 20px;
    background: var(--nav-bg);
    border: 1px solid var(--nav-border);
    border-radius: 50px;
    color: var(--nav-text);
    text-decoration: none;
    font-weight: 500;
    font-size: 14px;
    transition: var(--nav-transition);
    white-space: nowrap;
}

.nav-mode-simple .nav-simple-link:hover {
    background: var(--nav-primary);
    border-color: var(--nav-primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.nav-mode-simple .nav-simple-link svg {
    width: 18px;
    height: 18px;
    flex-shrink: 0;
    transition: var(--nav-transition);
}

.nav-mode-simple .nav-simple-link:hover svg {
    color: white;
}

.nav-mode-simple .nav-simple-prev .nav-simple-link:hover svg {
    transform: translateX(-3px);
}

.nav-mode-simple .nav-simple-next .nav-simple-link:hover svg {
    transform: translateX(3px);
}

.nav-mode-simple .nav-simple-text {
    color: inherit;
}

.nav-mode-simple .nav-simple-placeholder {
    width: 48px;
    height: 48px;
    opacity: 0;
}

/* 中間按鈕 - 簡單模式 */
.nav-mode-simple .nav-simple-center {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 12px;
    background: var(--nav-primary);
    border: 2px solid var(--nav-primary);
    border-radius: 50%;
    color: white;
    text-decoration: none;
    transition: var(--nav-transition);
    flex-shrink: 0;
    margin: 0px auto;
}

.nav-mode-simple .nav-simple-center:hover {
    background: var(--nav-primary-hover);
    border-color: var(--nav-primary-hover);
    transform: translateY(-2px) scale(1.1);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

.nav-mode-simple .nav-simple-center svg {
    width: 20px;
    height: 20px;
    color: white;
}

/* 形狀變體 */
.nav-mode-simple .nav-simple-center.shape-circle {
    border-radius: 50%;
    width: 48px;
    height: 48px;
    padding: 0;
}

.nav-mode-simple .nav-simple-center.shape-oval {
    border-radius: 50px;
    width: auto;
    height: auto;
    padding: 10px 24px;
    aspect-ratio: auto;
}

.nav-mode-simple .nav-simple-center.shape-square {
    border-radius: 4px;
    width: 48px;
    height: 48px;
    padding: 0;
}

.nav-mode-simple .nav-simple-center.shape-rounded {
    border-radius: 12px;
    width: 48px;
    height: 48px;
    padding: 0;
}

/* 風格變體 */
.nav-mode-simple .nav-simple-center.style-solid {
    background: var(--nav-primary);
    border-color: var(--nav-primary);
    color: white;
}

.nav-mode-simple .nav-simple-center.style-outline {
    background: transparent;
    border-color: var(--nav-border);
    color: var(--nav-text);
}

.nav-mode-simple .nav-simple-center.style-outline:hover {
    border-color: var(--nav-primary);
    color: var(--nav-primary);
    background: transparent;
}

.nav-mode-simple .nav-simple-center.style-outline svg {
    color: inherit;
}

.nav-mode-simple .nav-simple-center.style-flat {
    background: transparent;
    border-color: transparent;
    color: var(--nav-text);
    box-shadow: none;
}

.nav-mode-simple .nav-simple-center.style-flat:hover {
    background: var(--nav-bg-hover);
    color: var(--nav-primary);
    transform: translateY(-2px);
    box-shadow: none;
}

.nav-mode-simple .nav-simple-center.style-flat svg {
    color: inherit;
}

/* 簡單模式 - 極簡風格 (Minimal) */
.simple-style-minimal .nav-simple-link {
    background: transparent;
    border-color: transparent;
    padding: 10px 0; /* 減少左右 padding */
}

.simple-style-minimal .nav-simple-link:hover {
    background: transparent;
    border-color: transparent;
    color: var(--nav-primary);
    transform: none; /* 移除位移 */
    box-shadow: none;
}

.simple-style-minimal .nav-simple-link:hover svg {
    color: var(--nav-primary);
}

/* 簡單模式 - 響應式 */
@media (max-width: 768px) {
    .nav-mode-simple {
        gap: var(--nav-spacing-sm);
        padding: var(--nav-spacing-md) 0;
        /* 確保手機版堆疊模式生效 */
        flex-wrap: wrap; 
    }
    
    /* 手機版堆疊模式 - 簡單模式 */
    .post-navigation.mobile-stack.nav-mode-simple {
        flex-direction: column;
        align-items: stretch;
    }

    .post-navigation.mobile-stack.nav-mode-simple .nav-simple-prev,
    .post-navigation.mobile-stack.nav-mode-simple .nav-simple-next {
        justify-content: center; /* 堆疊時置中 */
        width: 100%;
    }

    .post-navigation.mobile-stack.nav-mode-simple .nav-simple-link {
        width: 100%;
        justify-content: center;
    }

    /* 手機版並排模式 (雙欄) - 簡單模式 */
    .post-navigation.mobile-columns.nav-mode-simple {
        flex-direction: row;
        flex-wrap: nowrap;
        align-items: center;
    }

    .post-navigation.mobile-columns.nav-mode-simple .nav-simple-prev,
    .post-navigation.mobile-columns.nav-mode-simple .nav-simple-next {
        flex: 1;
        width: auto;
        min-width: 0; /* 防止內容撐開 */
    }

    /* 確保連結內容在小螢幕不換行或適當縮放 */
    .post-navigation.mobile-columns.nav-mode-simple .nav-simple-link {
        width: 100%;
        justify-content: center;
        padding: 8px 4px; /* 減少內距以容納更多內容 */
    }
    
    /* 調整文字大小以適應並排 */
    .post-navigation.mobile-columns.nav-mode-simple .nav-simple-text {
        font-size: 12px;
        white-space: nowrap;
        overflow: hidden;
        text-overflow: ellipsis;
        max-width: 80px; /* 限制文字寬度 */
        display: inline-block;
    }
    
    .nav-mode-simple .nav-simple-link {
        padding: 8px 16px;
        font-size: 13px;
    }
    
    .nav-mode-simple .nav-simple-link svg {
        width: 16px;
        height: 16px;
    }
    
    .nav-mode-simple .nav-simple-center {
        padding: 10px;
    }
    
    .nav-mode-simple .nav-simple-center svg {
        width: 18px;
        height: 18px;
    }

    /* Mobile Columns Text Visibility */
    .post-navigation.mobile-columns.mobile-columns-text-hidden .nav-label-text,
    .post-navigation.mobile-columns.mobile-columns-text-hidden .nav-title,
    .post-navigation.mobile-columns.mobile-columns-text-hidden .nav-simple-text,
    .post-navigation.mobile-columns.mobile-columns-text-hidden .nav-compact-label,
    .post-navigation.mobile-columns.mobile-columns-text-hidden .nav-compact-title {
        display: none !important;
    }

    /* Adjust spacing when text is hidden */
    .post-navigation.mobile-columns.mobile-columns-text-hidden .nav-simple-link {
        justify-content: center;
        padding: 12px;
    }
}

/* Desktop Text Visibility */
@media (min-width: 1025px) {
    .post-navigation.desktop-text-hidden .nav-label-text,
    .post-navigation.desktop-text-hidden .nav-title,
    .post-navigation.desktop-text-hidden .nav-simple-text,
    .post-navigation.desktop-text-hidden .nav-compact-label,
    .post-navigation.desktop-text-hidden .nav-compact-title {
        display: none !important;
    }
    
    /* Adjust spacing/layout when text is hidden */
    .post-navigation.desktop-text-hidden .nav-simple-link {
        justify-content: center;
    }
}

/* Tablet Text Visibility */
@media (min-width: 769px) and (max-width: 1024px) {
    .post-navigation.tablet-text-hidden .nav-label-text,
    .post-navigation.tablet-text-hidden .nav-title,
    .post-navigation.tablet-text-hidden .nav-simple-text,
    .post-navigation.tablet-text-hidden .nav-compact-label,
    .post-navigation.tablet-text-hidden .nav-compact-title {
        display: none !important;
    }

    /* Adjust spacing/layout when text is hidden */
    .post-navigation.tablet-text-hidden .nav-simple-link {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .nav-mode-simple {
        gap: var(--nav-spacing-xs);
    }
    
    .nav-mode-simple .nav-simple-link {
        padding: 6px 12px;
        font-size: 12px;
    }
    
    /* .nav-mode-simple .nav-simple-text {
        display: none; 
    } */
    
    .nav-mode-simple .nav-simple-link svg {
        width: 20px;
        height: 20px;
    }
    
    .nav-mode-simple .nav-simple-center {
        padding: 8px;
    }
    
    .nav-mode-simple .nav-simple-center svg {
        width: 16px;
        height: 16px;
    }
}

/* ===================================== */


.post-navigation.loaded {
    opacity: 1;
    transform: translateY(0);
}


/* ========================================
   精簡導航模式 (Compact Mode)
======================================== */
.nav-mode-compact {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--nav-spacing-md);
    position: relative;
}

.nav-compact {
    flex: 1;
    max-width: calc(50% - var(--nav-spacing-md));
}

.nav-compact a {
    display: block;
    padding: var(--nav-spacing-md);
    background: var(--nav-bg);
    border: 1px solid var(--nav-border);
    border-radius: var(--nav-border-radius);
    text-decoration: none;
    transition: var(--nav-transition);
}

.nav-compact a:hover {
    background: var(--nav-bg-hover);
    border-color: var(--nav-primary);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.nav-compact-label {
    display: flex;
    align-items: center;
    gap: var(--nav-spacing-xs);
    font-size: 12px;
    color: var(--nav-primary);
    font-weight: 600;
    text-transform: uppercase;
    margin-bottom: var(--nav-spacing-xs);
}

.nav-compact-label svg {
    width: 14px;
    height: 14px;
}

.nav-compact-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--nav-text);
    margin: 0;
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.nav-compact a:hover .nav-compact-title {
    color: var(--nav-primary);
}

/* 精簡模式 - 中間按鈕 */
.nav-center-compact {
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    padding: 12px;
    border-radius: 50%;
    background: var(--nav-primary);
    border: 3px solid var(--nav-bg);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--nav-spacing-sm);
    text-decoration: none;
    transition: var(--nav-transition);
}

.nav-center-compact:hover {
    transform: translateX(-50%) scale(1.1);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

.nav-center-compact svg {
    width: 20px;
    height: 20px;
    color: white;
    display: block;
}

.nav-center-compact.has-text {
    border-radius: 50px;
    padding: 10px 20px;
}

.nav-center-compact .nav-center-text {
    color: white;
    font-weight: 600;
    font-size: 13px;
}

/* 精簡模式 - 響應式 */
@media (max-width: 768px) {
    .nav-mode-compact {
        flex-direction: column;
        gap: var(--nav-spacing-lg);
    }
    
    .nav-compact {
        max-width: 100%;
        width: 100%;
    }
    
    .nav-center-compact {
        position: static;
        transform: none;
        margin: calc(var(--nav-spacing-md) * -1) auto;
    }
    
    .nav-center-compact:hover {
        transform: scale(1.1);
    }
    
    /* 手機版隱藏文字 - 已移除 */
    /* .nav-center-compact.has-text .nav-center-text {
        display: none;
    } */
    
    .nav-center-compact.has-text {
        border-radius: 50%;
        padding: 10px;
        width: 44px;
        height: 44px;
    }
    
    .nav-center-compact.icon-only {
        width: 44px;
        height: 44px;
        padding: 10px;
    }
}

/**
 * 強制修正文章導航雙欄寬度不均的問題
 */
.post-navigation.has-both-posts {
    /* 移除 grid 佈局，改用更穩定的 flexbox 來處理 */
    display: flex;
    justify-content: space-between;
    grid-template-columns: none; /* 關閉 grid 的欄位設定 */
    gap: 0; /* 關閉 grid 的 gap */
    margin:40px auto;
}

.post-navigation .nav-item {
    /* 
     * 使用 flex 屬性進行彈性佈局
     * flex-grow: 1 -> 允許項目擴展
     * flex-shrink: 1 -> 允許項目收縮
     * flex-basis: calc(...) -> 理想的基礎寬度
     */
    flex: 1 1 calc( (100% - var(--nav-spacing-lg)) / 2 );
    
    /* 【關鍵備用】確保單個項目不會無限擴展 */
    max-width: calc( (100% - var(--nav-spacing-lg)) / 2 );
}

/* 針對只有一個項目的特殊情況 */
.post-navigation .nav-item:only-child {
    /* 當只有一個子元素時，取消其 flex-grow 屬性，防止它填滿整個寬度 */
    flex-grow: 0;
    
    /* 並且為了讓它能正確靠左或靠右，我們需要重置 justify-content */
}

/* 讓只有單個的「下一篇」按鈕能自動靠右 */
.post-navigation .nav-next:only-child {
    margin-left: auto;
}



/* ========================================
   卡片基本樣式
======================================== */
.nav-item {
    position: relative;
    background: var(--nav-bg);
    border-radius: var(--nav-border-radius);
    overflow: hidden;
    transition: var(--nav-transition);
    box-shadow: var(--nav-shadow);
    display: flex;
    flex-direction: column;
}

.nav-item a {
    display: flex;
    flex-direction: column;
    text-decoration: none;
    color: var(--nav-text);
    flex: 1;
    position: relative;
}

/* ========================================
   風格變化
======================================== */
.post-navigation-default .nav-item {
    border: 1px solid var(--nav-border);
}

.post-navigation-default .nav-item:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.12);
}

body.dark-mode .post-navigation-default .nav-item:hover {
    box-shadow: 0 8px 20px rgba(0,0,0,0.4);
}

.post-navigation-card .nav-item {
    box-shadow: 0 6px 16px rgba(0,0,0,0.08);
    border: none;
}

.post-navigation-card .nav-item:hover {
    box-shadow: 0 12px 28px rgba(0,0,0,0.15);
    transform: translateY(-6px) scale(1.02);
}

body.dark-mode .post-navigation-card .nav-item:hover {
    box-shadow: 0 12px 28px rgba(0,0,0,0.5);
}

.post-navigation-minimal .nav-item {
    box-shadow: none;
    border: 1px solid var(--nav-border);
    background: transparent;
}

.post-navigation-minimal .nav-item:hover {
    background: var(--nav-bg-hover);
    border-color: var(--nav-primary);
}

.post-navigation-minimal .nav-title {
    font-weight: 500;
}

.post-navigation-modern .nav-item {
    border: 2px solid transparent;
    background: linear-gradient(135deg, #f9fafb 0%, #ffffff 100%);
}

body.dark-mode .post-navigation-modern .nav-item {
    background: linear-gradient(135deg, #1f2937 0%, #111827 100%);
}

.post-navigation-modern .nav-item:hover {
    border-color: var(--nav-primary);
    background: var(--nav-bg);
    transform: translateY(-4px);
}

.post-navigation-modern .nav-title {
    background: linear-gradient(135deg, var(--nav-primary) 0%, #7c3aed 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.post-navigation-glass .nav-item {
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    box-shadow: 0 8px 32px rgba(0,0,0,0.1);
}

body.dark-mode .post-navigation-glass .nav-item {
    background: rgba(31, 41, 55, 0.7);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.post-navigation-glass .nav-item:hover {
    background: rgba(255, 255, 255, 0.85);
    transform: translateY(-4px);
}

body.dark-mode .post-navigation-glass .nav-item:hover {
    background: rgba(31, 41, 55, 0.85);
}

.post-navigation-gradient .nav-item {
    position: relative;
    background: var(--nav-bg);
}

.post-navigation-gradient .nav-item::before {
    content: '';
    position: absolute;
    inset: -2px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
    border-radius: calc(var(--nav-border-radius) + 2px);
    opacity: 0;
    transition: opacity 0.3s ease;
    z-index: -1;
}

.post-navigation-gradient .nav-item:hover::before {
    opacity: 1;
}

/* ========================================
   導航標籤樣式
======================================== */
.label-style-header .nav-label {
    display: flex;
    align-items: center;
    gap: var(--nav-spacing-sm);
    padding: var(--nav-spacing-md);
    padding-bottom: var(--nav-spacing-sm);
    font-size: 14px;
    font-weight: 600;
    color: var(--nav-primary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.label-style-header .nav-previous .nav-label {
    justify-content: flex-start;
}

.label-style-header .nav-next .nav-label {
    justify-content: flex-end;
}

.label-style-header .nav-label-icon {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
    color: var(--nav-primary);
}

.label-style-header .nav-label-text {
    color: var(--nav-primary);
}

.label-style-overlay .nav-label {
    position: absolute;
    z-index: 10;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: var(--nav-spacing-sm) var(--nav-spacing-md);
    border-radius: 6px;
    font-size: 13px;
    font-weight: 600;
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    gap: var(--nav-spacing-xs);
}

.label-style-overlay .nav-label * {
    color: white;
}

.label-style-overlay .nav-previous .nav-label {
    top: var(--nav-spacing-md);
    left: var(--nav-spacing-md);
}

.label-style-overlay .nav-next .nav-label {
    top: var(--nav-spacing-md);
    right: var(--nav-spacing-md);
}

.label-style-arrow .nav-label {
    display: none;
}

.label-style-arrow .nav-arrow-indicator {
    display: flex !important;
    align-items: center;
    justify-content: center;
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 48px;
    height: 48px;
    background: var(--nav-primary);
    color: white;
    border-radius: 50%;
    opacity: 0;
    transition: var(--nav-transition);
    z-index: 10;
    pointer-events: none;
}

.label-style-arrow .nav-arrow-indicator svg {
    color: white;
    stroke: white;
}

.label-style-arrow .nav-previous .nav-arrow-indicator {
    left: var(--nav-spacing-md);
}

.label-style-arrow .nav-next .nav-arrow-indicator {
    right: var(--nav-spacing-md);
}

.label-style-arrow .nav-item:hover .nav-arrow-indicator {
    opacity: 1;
}

.nav-arrow-indicator {
    display: none;
}

/* ========================================
   響應式佈局系統 - 關鍵修正
======================================== */

/* 主容器 */
.nav-main {
    display: flex;
    flex: 1;
    width: 100%; 
}

/* 桌機版 - 圖片在上方(滿版) */
.layout-desktop-top .nav-main {
    flex-direction: column;
}

.layout-desktop-top .nav-thumb {
    width: 100%;
    position: relative;
    flex-shrink: 0;
}

/* 使用 padding-bottom 維持長寬比 */
.layout-desktop-top .nav-thumb::after {
    content: '';
    display: block;
    padding-bottom: calc(100% / (var(--post-nav-top-img-ratio)));
}

.layout-desktop-top .nav-thumb img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* 桌機版 - 圖片在側邊 */
.layout-desktop-side .nav-main {
    flex-direction: row;
    gap: var(--nav-spacing-md);
}

.layout-desktop-side .nav-thumb {
    flex-shrink: 0;
    width: var(--post-nav-side-img-width);
    height: var(--post-nav-side-img-height);
    position: relative;
}

.layout-desktop-side .nav-thumb img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.layout-desktop-side .desktop-image-left .nav-main {
    flex-direction: row;
}

.layout-desktop-side .desktop-image-right .nav-main {
    flex-direction: row-reverse;
}

/* 垂直對齊 */
.valign-center.layout-desktop-side .nav-main {
    align-items: center;
}

.valign-top.layout-desktop-side .nav-main {
    align-items: flex-start;
}

/* ========================================
   圖片樣式
======================================== */
.nav-thumb {
    overflow: hidden;
    background: #f3f4f6;
}

body.dark-mode .nav-thumb {
    background: #374151;
}

.nav-thumb img {
    width: 100%;
    height: 100%;
    object-fit: var(--post-nav-img-fit);
    transition: var(--nav-transition);
    display: block;
}

/* Hover 效果 */
.nav-item:hover .nav-thumb img {
    transform: scale(1.1);
}

[style*="--nav-hover-effect: none"] .nav-item:hover .nav-thumb img {
    transform: none;
}

[style*="--nav-hover-effect: brightness"] .nav-item:hover .nav-thumb img {
    transform: none;
    filter: brightness(1.1);
}

/* 圖片載入骨架 */
.nav-thumb::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(90deg, #f3f4f6 25%, #e5e7eb 50%, #f3f4f6 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s infinite;
    z-index: 1;
    pointer-events: none;
    opacity: 1;
    transition: opacity 0.3s ease;
}

body.dark-mode .nav-thumb::before {
    background: linear-gradient(90deg, #374151 25%, #4b5563 50%, #374151 75%);
}

/* 圖片載入完成後立即停止動畫並隱藏骨架 */
.nav-thumb.image-loaded::before {
    animation: none !important;
    opacity: 0;
    display: none;
}

/* 圖片本身也在 z-index 之上 */
.nav-thumb img {
    position: relative;
    z-index: 2;
}

@keyframes skeleton-loading {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* ========================================
   內容區樣式
======================================== */
.nav-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--nav-spacing-sm);
    padding: var(--nav-spacing-md);
    min-width: 0;
    justify-content: space-between; /* <-- 新增這一行 */
}
/* ========================================
   標題樣式
======================================== */
.nav-title {
    font-size: 18px;
    font-weight: 700;
    line-height: 1.4; /* 關鍵：行高為 1.4 */
    color: var(--nav-text);
    margin: 0;
    display: -webkit-box;
    -webkit-line-clamp: var(--post-nav-title-lines);
    -webkit-box-orient: vertical;
    overflow: hidden;
    text-overflow: ellipsis;
    transition: color 0.2s ease;
    /* ▼▼▼ 新增這一行 ▼▼▼ */
    min-height: calc(1.4em * var(--post-nav-title-lines));
}

.nav-item:hover .nav-title {
    color: var(--nav-primary);
}

.post-navigation-modern .nav-title {
    position: relative;
    padding-bottom: 4px;
}

.post-navigation-modern .nav-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--nav-primary);
    transition: width 0.3s ease;
}

.post-navigation-modern .nav-item:hover .nav-title::after {
    width: 100%;
}

.post-navigation-card .nav-item:hover .nav-title {
    font-weight: 800;
}

/* ========================================
   Meta 資訊樣式
======================================== */
.nav-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--nav-spacing-md);
    font-size: 13px;
    color: var(--nav-text-secondary);
    margin-top: var(--nav-spacing-xs);
}

.nav-meta > * {
    display: flex;
    align-items: center;
    gap: 6px;
    color: var(--nav-text-secondary);
}

.nav-meta svg {
    width: 14px;
    height: 14px;
    flex-shrink: 0;
    opacity: 0.7;
}

.nav-category {
    background: #dbeafe;
    color: #1e40af;
    padding: 4px 10px;
    border-radius: 4px;
    font-weight: 500;
}

body.dark-mode .nav-category {
    background: rgba(37, 99, 235, 0.2);
    color: #93c5fd;
}

.nav-date,
.nav-read-time,
.nav-author {
    opacity: 0.8;
}

.nav-item:hover .nav-meta > * {
    opacity: 1;
}

/* ========================================
   摘要樣式
======================================== */
.nav-excerpt {
    font-size: 14px;
    line-height: 1.6;
    color: var(--nav-text-secondary);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    text-overflow: ellipsis;
    margin-top: auto;
}

.nav-item:hover .nav-excerpt {
    color: var(--nav-text);
}

/* ========================================
   載入動畫
======================================== */
.animation-none {
    opacity: 1;
    transform: none;
}

.animation-fade-up.loaded {
    animation: fadeUp 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

@keyframes fadeUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animation-fade-in.loaded {
    animation: fadeIn 0.6s ease forwards;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.animation-slide-in .nav-previous {
    transform: translateX(-30px);
}

.animation-slide-in .nav-next {
    transform: translateX(30px);
}

.animation-slide-in.loaded .nav-item {
    animation: slideIn 0.6s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

@keyframes slideIn {
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* ========================================
   響應式斷點 - 平板
======================================== */
@media (max-width: 1024px) and (min-width: 769px) {
    .layout-tablet-top .nav-main {
        flex-direction: column !important;
    }
    
    .layout-tablet-top .nav-thumb {
        width: 100% !important;
        height: auto !important;
    }
    
    .layout-tablet-side .tablet-image-left .nav-main {
        flex-direction: row !important;
    }
    
    .layout-tablet-side .tablet-image-right .nav-main {
        flex-direction: row-reverse !important;
    }
}

/* ========================================
   響應式斷點 - 手機(根據後台設定)
======================================== */
@media (max-width: 768px) {
    .nav-title {
        font-size: 16px;
    }
    
    .nav-content {
        padding: var(--nav-spacing-md);
    }
    
    .nav-meta {
        font-size: 12px;
        gap: var(--nav-spacing-sm);
    }
    
    .nav-excerpt {
        font-size: 13px;
    }
    
    /* 手機版堆疊模式(由後台設定控制) - 修正 */
    .post-navigation.mobile-stack.has-both-posts {
        flex-direction: column; /* 1. 將主軸方向改為垂直 */
        gap: var(--nav-spacing-md); /* 2. 設定堆疊間距 */
    }

    .post-navigation.mobile-stack.has-both-posts .nav-item {
        width: 100%; /* 3. 將導航項目寬度重設為 100% */
    }

    /* 當只有單一導航項目時，也確保其為單欄 */
    .post-navigation.mobile-stack:not(.has-both-posts) {
        grid-template-columns: 1fr;
    }
    
    /* 手機版並排模式(保持雙欄) */
    .post-navigation.mobile-columns.has-both-posts {
        grid-template-columns: repeat(2, 1fr) !important;
        gap: var(--nav-spacing-sm);
    }
    
    /* 手機版並排時縮小字體 */
    .post-navigation.mobile-columns .nav-title {
        font-size: 14px;
        -webkit-line-clamp: 2;
    }
    
    .post-navigation.mobile-columns .nav-content {
        padding: var(--nav-spacing-sm);
    }
    
    .post-navigation.mobile-columns .nav-excerpt {
        font-size: 12px;
        -webkit-line-clamp: 1;
    }
    
    /* 手機版強制上方佈局 */
    .layout-mobile-top .nav-main {
        flex-direction: column !important;
    }
    
    .layout-mobile-top .nav-thumb {
        width: 100% !important;
        height: auto !important;
    }
    
    /* 手機版側邊佈局 */
    .layout-mobile-side .mobile-image-left .nav-main {
        flex-direction: row !important;
    }
    
    .layout-mobile-side .mobile-image-right .nav-main {
        flex-direction: row-reverse !important;
    }
    
    .layout-mobile-side .nav-thumb {
        width: 100px !important;
        height: 100px !important;
    }
    
    .label-style-arrow .nav-arrow-indicator {
        width: 36px;
        height: 36px;
    }

    /* 手機版堆疊模式(由後台設定控制) - 修正 */
    .post-navigation.mobile-stack { /* .has-both-posts 已被移除，更通用 */
        flex-direction: column; /* 1. 將主軸方向改為垂直 */
        gap: var(--nav-spacing-md); /* 2. 設定堆疊間距 */
    }

    .post-navigation.mobile-stack .nav-item,
    .post-navigation.mobile-stack .nav-item:only-child {
        width: 100%; /* 3. 將導航項目寬度重設為 100% */
        max-width: 100%; /* 4. 同時也要重設 max-width */
        margin-left: 0; /* 5. 重置 margin */
    }


    /* ========== 新增箭頭模式手機版 ========== */
    .nav-mode-arrow {
        gap: var(--nav-spacing-md);
    }
    
    .nav-arrow {
        padding: 10px 16px;
        font-size: 13px;
    }
    
    /* .nav-arrow-text {
        display: none; 
    } */
    
    .nav-arrow svg {
        width: 18px;
        height: 18px;
    }
    
    .nav-center-button {
        padding: 10px 16px;
    }
    
    /* .nav-center-text {
        display: none; 
    } */
    
    .nav-center-button svg {
        width: 18px;
        height: 18px;
    }


}
/* ========== 新增極小螢幕優化 ========== */
@media (max-width: 480px) {
    .nav-mode-arrow {
        gap: var(--nav-spacing-sm);
    }
    
    .nav-arrow {
        padding: 8px 12px;
    }
    
    .nav-center-button {
        padding: 8px 12px;
    }
}
/* ===================================== */

/* ========================================
   無障礙增強
======================================== */
.nav-item a:focus-visible {
    outline: 3px solid var(--nav-primary);
    outline-offset: 4px;
}


/* ========================================
   列印樣式
======================================== */
@media print {
    .post-navigation {
        break-inside: avoid;
        box-shadow: none !important;
    }
    
    .nav-item {
        border: 1px solid #ddd !important;
        page-break-inside: avoid;
    }
    
    .nav-arrow-indicator,
    .keyboard-hint,
    .dark-mode-toggle {
        display: none !important;
    }
}

/* ========================================
   效能優化
======================================== */
.post-navigation * {
    will-change: auto;
}

.nav-item:hover {
    will-change: transform, box-shadow;
}

.nav-thumb img {
    content-visibility: auto;
}

/* ========================================
   針對小螢幕裝置的字體優化
======================================== */
@media (max-width: 480px) {
    .post-navigation .nav-title {
        /* 在螢幕寬度小於 480px 時，將標題字體縮小到 15px */
        font-size: 15px; 
    }

    /* 如果您希望在小螢幕上並排顯示時，摘要也少顯示一點 */
    .post-navigation.mobile-columns .nav-excerpt {
        -webkit-line-clamp: 1; /* 摘要只顯示 1 行 */
    }
}

/*
 * 現代化的 Clearfix 技巧
 * 應用於主內容與側邊欄的外層容器
 */
/* #postshow-all::after {
    content: ""; 
    display: table;  
    clear: both;     
}*/

/* 
 * 同時，建議為您的主容器 .container 也加上，確保萬無一失
 */
/*.container::after {
    content: "";
    display: table;
    clear: both;
}*/