/* =========================================
   1. 核心变量 & 基础样式
   ========================================= */
:root {
    /* --- 浅色模式 --- */
    --bg-color: #f5f5f7;
    --paper-bg: #ffffff;
    --text-primary: #1d1d1f;
    --text-secondary: gray;
    --accent-color: #0165e2;
    --accent-color-t: #0166e2c2;
    --border-color: #d2d2d7;

    /* 粉色高亮 */
    --mark-bg: rgba(255, 20, 147, 0.3);
    --mark-hover: rgba(255, 20, 147, 0.6);
    --tab-active-bg: #1d1d1f;
    --tab-active-text: #ffffff;
    --tab-inactive-bg: rgba(0, 0, 0, 0.05);
    --tab-inactive-text: #1d1d1f;

    /* Header 背景 */
    --header-bg: rgba(255, 255, 255, 0.85);
    --option-bg: rgba(255, 255, 255, 0.98);

    --word-span-hover: rgba(0, 0, 0, 0.05);

    /* 下拉菜单伪元素背景色 */
    --dropdown-pseudo-bg: rgba(255, 255, 255, 0.85);

    --paper-shadow: 0 10px 40px rgba(0, 0, 0, 0.06);
    --hover-bg: rgba(0, 0, 0, 0.05);
    
    /* Next Card */
    --card-hover-bg: #f5f5f7;
}

@media (prefers-color-scheme: dark) {
    :root {
        /* --- 深色模式 --- */
        --bg-color: #000000;
        --paper-bg: #1c1c1e;
        --text-primary: #f5f5f7;
        --text-secondary: #98989d;
        --accent-color: #005ad1;
        --accent-color-t: #005ad1c2;
        --border-color: #38383a;

        --mark-bg: rgba(255, 105, 180, 0.45);
        --mark-hover: rgba(255, 105, 180, 0.75);
        --tab-active-bg: #f5f5f7;
        --tab-active-text: #000000;
        --tab-inactive-bg: rgba(255, 255, 255, 0.1);
        --tab-inactive-text: #f5f5f7;

        --header-bg: rgba(28, 28, 30, 0.8);
        --option-bg: rgb(34, 33, 33, 0.95);
        --hover-bg: rgba(255, 255, 255, 0.1);

        --word-span-hover: rgb(255 255 255 / 15%);

        --dropdown-pseudo-bg: rgba(40, 40, 45, 0.9);
        --paper-shadow: none;
        
        --card-hover-bg: #2c2c2e;
    }
}

/* 1. 针对 WebKit 内核浏览器 */
::-webkit-scrollbar {
    display: none;
}

/* 2. 针对 Firefox 和 IE/Legacy Edge */
html {
    scrollbar-width: none;
    -ms-overflow-style: none;
}

/* 3. 全局滚动条隐藏 */
* {
    scrollbar-width: none;
    -ms-overflow-style: none;
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
    overflow-x: hidden;
}

/* =========================================
   2. 顶部导航
   ========================================= */
header {
    position: sticky;
    top: 0;
    background-color: var(--header-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    padding: 16px 0;
    transition: all 0.3s ease;
}

.header-container {
    max-width: 1600px;
    margin: 0 auto;
    padding: 0 60px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* --- 阅读进度条 --- */
.reading-progress-container {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: transparent;
    pointer-events: none;
}

.reading-progress-bar {
    height: 100%;
    width: 0%;
    background-color: var(--accent-color);
    transition: width 0.1s linear;
    border-top-right-radius: 2px;
    border-bottom-right-radius: 2px;
}

/* --- 下拉菜单 --- */
.custom-select-wrapper {
    position: relative;
    user-select: none;
    min-width: 140px;
}

.select-trigger {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    padding: 8px 0;
    transition: opacity 0.2s;
}

.select-trigger:active {
    opacity: 0.6;
}

.unit-label-small {
    font-size: 11px;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 2px;
}

.current-unit-display {
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
    font-family: -apple-system, sans-serif;
}

.trigger-arrow {
    font-size: 12px;
    color: var(--text-secondary);
    transition: transform 0.3s ease;
}

.custom-select-wrapper.open .trigger-arrow {
    transform: rotate(180deg);
}

.select-options {
    position: absolute;
    top: 120%;
    left: -10px;
    background-color: var(--option-bg);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 6px;
    min-width: 200px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px) scale(0.98);
    transition: all 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
    max-height: 60vh;
    overflow-y: auto;
    z-index: 1001;
}

.custom-select-wrapper.open .select-options {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
}

.option-item {
    padding: 10px 14px;
    font-size: 15px;
    font-weight: 500;
    margin: 2px 0;
    color: var(--text-primary);
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.2s;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.option-item:hover {
    background-color: var(--hover-bg);
}

.option-item.selected {
    color: var(--accent-color);
    background-color: var(--hover-bg);
}

.option-item.selected::after {
    content: "✓";
    font-weight: bold;
}

/* --- Text Tabs --- */
.tabs-container {
    display: flex;
    gap: 8px;
    background: transparent;
    overflow-x: auto;
    scrollbar-width: none;
    margin-right: 15px;
}

.tabs-container::-webkit-scrollbar {
    display: none;
}

.tab-btn {
    padding: 6px 16px;
    border-radius: 18px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    border: none;
    outline: none;
    background-color: var(--tab-inactive-bg);
    color: var(--tab-inactive-text);
    white-space: nowrap;
}

.tab-btn:hover {
    background-color: var(--hover-bg);
}

.tab-btn:active {
    transform: scale(0.95);
}

.tab-btn.active {
    background-color: var(--tab-active-bg);
    color: var(--tab-active-text);
}

/* =========================================
   3. 内容区域
   ========================================= */
#content-area {
    width: 100%;
    max-width: 1200px;
    margin: 40px auto 60px auto;
    padding: 80px 80px 60px 80px;
    background-color: var(--paper-bg);
    border-radius: 16px;
    box-shadow: var(--paper-shadow);
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    min-height: 80vh;
    position: relative;
    animation: contentFadeUp 0.6s ease-out;
}

@keyframes contentFadeUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.article-title {
    font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", Roboto, sans-serif;
    font-size: clamp(32px, 5vw, 64px);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 16px;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.article-author {
    font-family: "Charter", "Georgia", serif;
    font-size: clamp(16px, 1.5vw, 20px);
    font-style: italic;
    color: var(--text-secondary);
    margin-bottom: 50px;
    display: flex;
    align-items: center;
}

.article-author::before {
    content: "By";
    font-family: -apple-system, sans-serif;
    font-style: normal;
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-right: 8px;
    padding: 2px 6px;
    background-color: var(--tab-inactive-bg);
    border-radius: 4px;
    color: var(--text-secondary);
}

.section-subtitle {
    margin: 50px 0 25px 0;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 8px;
    width: 100%;
}

.section-subtitle h4,
.section-subtitle h3 {
    font-family: -apple-system, BlinkMacSystemFont, sans-serif;
    font-size: 22px;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
    letter-spacing: -0.01em;
}

.paragraph-pair {
    margin-bottom: 48px;
    width: 100%;
}

.en-text {
    font-family: "Charter", "Georgia", serif;
    font-size: clamp(20px, 2.2vw, 32px);
    color: var(--text-primary);
    line-height: 1.6;
    margin-bottom: 16px;
    font-weight: 400;
    max-width: 100%;
}

.cn-text {
    font-family: -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
    font-size: clamp(15px, 1.6vw, 18px);
    color: var(--text-secondary);
    line-height: 1.8;
    margin-top: 8px;
}

u {
    text-decoration: none;
    background-image: linear-gradient(120deg, var(--mark-bg) 0%, var(--mark-bg) 100%);
    background-repeat: no-repeat;
    background-size: 100% 0.4em;
    background-position: 0 88%;
    transition: all 0.25s ease;
    border-radius: 2px;
    padding: 0 1px;
    color: var(--text-primary);
    font-weight: 500;
}

u:hover {
    background-size: 100% 100%;
    background-color: var(--mark-hover);
    color: #000;
}

.note-index {
    display: inline-block;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    font-size: 0.75em;
    font-weight: 700;
    color: var(--accent-color);
    vertical-align: top;    
    position: relative;
    top: -0.3em;
    margin-left: 2px;
    background-color: transparent;
    padding: 0;
    min-width: auto;
    height: auto;
    border-radius: 0;
    box-shadow: none;
    transform: none;
}

.divider {
    border: 0;
    height: 1px;
    background-image: linear-gradient(to right, transparent, var(--border-color), transparent);
    margin: 60px 0;
    position: relative;
    overflow: visible;
    text-align: center;
}

.divider::after {
    content: "❖";
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: var(--paper-bg);
    padding: 0 15px;
    color: var(--border-color);
    font-size: 12px;
}

b, strong {
    font-weight: 700;
    color: var(--text-primary);
}


/* =========================================
   4. 底部 "下一篇" 卡片
   ========================================= */
.next-card-container {
    margin-top: 80px;
    width: 100%;
    border-top: 1px solid var(--border-color);
    padding-top: 40px;
}

.next-label {
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--text-secondary);
    letter-spacing: 2px;
    margin-bottom: 20px;
    opacity: 0.8;
}

.next-card {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    text-decoration: none;
    cursor: pointer;
    padding: 30px 40px;
    border-radius: 20px;
    background-color: var(--bg-color);
    transition: all 0.4s cubic-bezier(0.165, 0.84, 0.44, 1);
    border: 1px solid transparent;
    position: relative;
    overflow: hidden;
}

.next-card:hover {
    background-color: var(--card-hover-bg);
    border-color: var(--accent-color);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.08);
    transform: translateY(-6px);
}

.next-card:active {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

.next-card-content {
    flex: 1;
}

.next-card-title {
    font-family: "Charter", serif;
    font-size: clamp(20px, 2.5vw, 36px);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 8px;
    transition: color 0.3s;
}

.next-card:hover .next-card-title {
    color: var(--accent-color);
}

.next-card-meta {
    font-size: 14px;
    color: var(--text-secondary);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.next-card-icon {
    margin-left: 20px;
    color: var(--text-secondary);
    transition: transform 0.3s, color 0.3s;
    display: flex;
    align-items: center;
}

.next-card:hover .next-card-icon {
    transform: translateX(5px);
    color: var(--accent-color);
}

/* =========================================
   5. Loading & Error & Controls
   ========================================= */
#loading-state, #error-state {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    width: 100%;
}

.spinner {
    width: 36px;
    height: 36px;
    margin: 0 auto 20px auto;
    border: 3px solid rgba(0, 0, 0, 0.1);
    border-left-color: var(--accent-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    100% { transform: rotate(360deg); }
}

.loading-text {
    font-size: 15px;
    color: var(--text-secondary);
    font-weight: 500;
}

.retry-btn {
    padding: 8px 24px;
    background: var(--accent-color);
    color: #fff;
    border: none;
    border-radius: 20px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.1s;
}
.retry-btn:active { transform: scale(0.95); }

/* --- Controls (Listen & CN) --- */
.controls-area {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-left: 10px;
}

.icon-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 18px;
    padding: 6px 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    transition: all 0.2s;
    outline: none;
    text-decoration: none;
    color: var(--text-primary);
    height: 34px;
}

.icon-btn:hover {
    background-color: var(--hover-bg);
    border-color: var(--text-secondary);
}

.icon-btn:active {
    transform: scale(0.92);
}

.btn-label {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-primary);
}

.toggle-indicator {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background-color: var(--accent-color);
    box-shadow: 0 0 4px var(--accent-color);
    transition: all 0.3s;
}

.icon-btn.off .toggle-indicator {
    background-color: var(--text-secondary);
    box-shadow: none;
    opacity: 0.4;
}

.icon-btn.off .btn-label {
    opacity: 0.6;
}

/* =========================================
   6. 移动端优化
   ========================================= */
@media (max-width: 768px) {
    header { padding: 12px 0; }
    .header-container { padding: 0 16px; }
    .custom-select-wrapper { min-width: auto; }
    .unit-label-small { display: none; }
    .current-unit-display { font-size: 16px; max-width: 120px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
    .tabs-container { margin-right: 8px; max-width: 120px; }
    .tab-btn { padding: 4px 12px; font-size: 12px; }
    .controls-area { margin-left: 5px; gap: 6px; }
    .icon-btn { padding: 0 8px; height: 30px; width: 30px; }
    .mobile-hide { display: none; }
    #toggle-cn-btn { width: auto; padding: 0 8px; }
    #content-area { margin: 20px auto; padding: 40px 20px; border-radius: 0; box-shadow: none; width: 100%; max-width: 100%; }
    .article-title { font-size: 32px; margin-bottom: 10px; }
    .article-author { margin-bottom: 30px; }
    .en-text { font-size: 20px; line-height: 1.5; }
    .cn-text { font-size: 15px; }
    .next-card { padding: 20px; flex-direction: column; align-items: flex-start; }
    .next-card-icon { margin-left: 0; margin-top: 10px; align-self: flex-end; }
}

/* =========================================
   7. 单词高亮与交互 (统一逻辑：普通词 + 重点词)
   ========================================= */

/* A. 基础样式：统一圆角、过渡、变量 */
.word-span, 
.vocab-match {
    cursor: pointer;
    border-radius: 4px;
    margin: 0; 
    position: relative;
    z-index: 1;
    -webkit-box-decoration-break: clone;
    box-decoration-break: clone;

    /* 定义动画延迟变量 (用于波浪动画) */
    --delay-factor: 0;

    /* 基础过渡 */
    transition: background-color 0.1s ease, color 0.1s ease, box-shadow 0.2s ease;
}

/* B. 悬停状态 (Pre-selection) */
@media (hover: hover) {
    .word-span:hover,
    .vocab-match:hover { 
        background-color: var(--word-span-hover); 
    }
}

/* C. 拖拽过程中的临时高亮 (动画层) */
.word-span.temp-selected, 
.vocab-match.temp-selected {
    background-color: var(--accent-color-t) !important; /* !important 确保覆盖重点词的原有颜色 */
    color: #fff !important; 
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);

    /* 核心波浪动画：距离越远，delay越大 */
    transition: background-color 0.2s cubic-bezier(0.2, 0.8, 0.2, 1),
                color 0.2s cubic-bezier(0.2, 0.8, 0.2, 1);
    transition-delay: calc(var(--delay-factor) * 0.015s);
}

/* D. 最终选中状态 (定格) */
.word-span.selected, 
.vocab-match.selected { 
    background-color: var(--accent-color) !important; 
    color: #fff !important; 
    box-shadow: 0 1px 3px rgba(0, 113, 227, 0.25);
    z-index: 2;
    /* 最终状态取消延迟，确保稳定 */
    transition: background-color 0.1s ease, color 0.1s ease;
    transition-delay: 0s;
}

/* E. 重点词汇的默认样式 (未被拖拽选中时) */
/* 这里定义重点词的默认颜色，注意它们会被上面的 temp-selected 和 selected 覆盖 */
.vocab-match {
    border-bottom: 2px solid;
    padding-bottom: 0px;
    font-weight: 600;
}

/* 单词类型 */
.vocab-match.type-word { 
    color: #d97706; 
    border-bottom-color: #fcd34d; 
    background-color: rgba(252, 211, 77, 0.1); 
}
/* 短语类型 */
.vocab-match.type-phrase { 
    color: #7c3aed; 
    border-bottom-color: #c4b5fd; 
    background-color: rgba(196, 181, 253, 0.1); 
}

/* 移除旧的 hover 逻辑，因为上方已统一处理 */
/* .vocab-match.type-word:hover ... (Deleted) */

/* =========================================
   8. 弹窗与工具栏
   ========================================= */
.vocab-popup {
    position: fixed;
    z-index: 2000;
    background-color: var(--paper-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 16px;
    width: 280px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    font-family: -apple-system, sans-serif;
    display: none;
    
    /* 默认：从弹窗底部中心生长 (弹窗在上方) */
    transform-origin: bottom center; 
    animation: popupSpring 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.15) forwards;
    
    opacity: 0;
    /* 初始稍微向下偏移，配合动画向上浮动 */
    transform: translateY(10px) scale(0.95);
}

/* 当弹窗在下方时 (.arrow-top)，改变动画原点 */
.vocab-popup.arrow-top {
    transform-origin: top center;
}

@keyframes popupSpring {
    0% { opacity: 0; transform: translateY(8px) scale(0.96); }
    60% { opacity: 1; transform: translateY(-2px) scale(1.005); }
    100% { opacity: 1; transform: translateY(0) scale(1); }
}

.popup-header { display: flex; align-items: baseline; gap: 10px; margin-bottom: 12px; border-bottom: 1px solid var(--border-color); padding-bottom: 8px; }
#popup-term { font-size: 18px; font-weight: 700; color: var(--text-primary); line-height: 1.2; }
#popup-phonetic { font-size: 13px; color: var(--text-secondary); background: var(--hover-bg); padding: 2px 6px; border-radius: 4px; }
.popup-def { max-height: 200px; overflow-y: auto; }
.def-row { gap: 8px; margin-bottom: 10px; align-items: flex-start; }
.pos-tag { font-size: 11px; font-weight: 700; color: var(--accent-color); background-color: var(--tab-inactive-bg); padding: 2px 5px; border-radius: 4px; min-width: 24px; text-align: center; margin-top: 2px; font-style: italic; }
.def-cn { font-size: 14px; font-weight: 500; color: var(--text-primary); display: inline; margin-left: 5px; }
.def-en { font-size: 12px; display: block; color: var(--text-secondary); margin-top: 2px; line-height: 1.4; }
.popup-arrow {
    position: absolute;
    left: 50%;
    width: 12px;
    height: 12px;
    background-color: var(--paper-bg);
    
    /* 利用旋转正方形制作三角形 */
    transform: translateX(-50%) rotate(45deg);
    
    /* 默认情况：弹窗在上面，箭头在底部 */
    bottom: -7px; 
    top: auto;
    
    /* 箭头的边框 (右下边框构成向下的尖角) */
    border-right: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
    border-top: none;
    border-left: none;
    
    z-index: 2001;
}

/* 翻转样式：当弹窗在下方时 (.arrow-top)，箭头跑到顶部指向上方 */
.vocab-popup.arrow-top .popup-arrow {
    bottom: auto;
    top: -7px; /* 移到顶部 */
    
    /* 改变边框方向 (左上边框构成向上的尖角) */
    border-right: none;
    border-bottom: none;
    border-top: 1px solid var(--border-color);
    border-left: 1px solid var(--border-color);
}
/* CN 隐藏模式 */
.hide-cn .cn-text { filter: blur(8px); user-select: none; transition: filter 0.3s; cursor: pointer; opacity: 0.7; }
.hide-cn .cn-text.revealed { filter: blur(0); user-select: text; opacity: 1; cursor: text; }

/* Selection Toolbar */
.selection-toolbar { position: fixed; z-index: 2100; background-color: #1d1d1f; color: #fff; border-radius: 8px; padding: 0 4px; display: flex; align-items: center; box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2); font-size: 14px; animation: toolbarSlideUp 0.25s cubic-bezier(0.16, 1, 0.3, 1) forwards; transform-origin: bottom center; }
@keyframes toolbarSlideUp {
    from { opacity: 0; transform: translateY(5px) scale(0.98); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}
.selection-toolbar button { background: transparent; border: none; color: #fff; padding: 8px 12px; font-size: 13px; font-weight: 600; cursor: pointer; }
.toolbar-divider { width: 1px; height: 14px; background-color: rgba(255, 255, 255, 0.2); }
.toolbar-arrow { position: absolute; bottom: -5px; left: 50%; transform: translateX(-50%) rotate(45deg); width: 10px; height: 10px; background-color: #1d1d1f; }