/* ============================
   CSS Variables & Reset
   ============================ */
:root {
    /* 深色主题色板 */
    --bg-primary: #0f1119;
    --bg-secondary: #161822;
    --bg-card: #1c1f2e;
    --bg-card-hover: #242840;
    --bg-highlight: rgba(99, 102, 241, 0.12);

    /* 强调色 */
    --accent-primary: #818cf8;
    --accent-secondary: #a78bfa;
    --accent-gradient: linear-gradient(135deg, #818cf8 0%, #a78bfa 100%);
    --accent-glow: 0 0 20px rgba(129, 140, 248, 0.3);

    /* 文字颜色 */
    --text-primary: #e8eaf0;
    --text-secondary: #9ca3af;
    --text-muted: #6b7280;
    --text-phonetic: #8b8fa8;
    --text-translation: #a5b4fc;

    /* 语义色 */
    --color-success: #34d399;
    --color-warning: #fbbf24;
    --color-info: #60a5fa;
    --color-vocab: #f472b6;
    --color-phrase: #38bdf8;

    /* 间距 & 尺寸 */
    --header-height: 60px;
    --footer-height: 56px;
    --border-radius: 12px;
    --border-radius-sm: 8px;
    --gap: 16px;

    /* 字体 */
    --font-en: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-cn: 'Noto Sans SC', -apple-system, 'PingFang SC', sans-serif;
    --font-size-base: 17px;

    /* 安全区域 */
    --safe-area-left: env(safe-area-inset-left);
    --safe-area-right: env(safe-area-inset-right);
    --safe-area-top: env(safe-area-inset-top);
    --safe-area-bottom: env(safe-area-inset-bottom);

    /* 过渡 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
    font-family: var(--font-en);
    background: var(--bg-primary);
    color: var(--text-primary);
    height: 100vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    padding-left: var(--safe-area-left);
    padding-right: var(--safe-area-right);
    padding-bottom: var(--safe-area-bottom);
}

/* ============================
   Header / 导航栏
   ============================ */
#app-header {
    height: var(--header-height);
    background: rgba(22, 24, 34, 0.7);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    padding-top: var(--safe-area-top);
    flex-shrink: 0;
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: 100;
}

.header-left h1 {
    font-size: 1.15rem;
    font-weight: 600;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    white-space: nowrap;
    max-width: 260px;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* 模式切换 */
.mode-switch {
    position: relative;
    display: flex;
    background: var(--bg-card);
    border-radius: 28px;
    padding: 3px;
    gap: 2px;
}

.mode-btn {
    position: relative;
    z-index: 2;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-family: var(--font-cn);
    font-size: 0.82rem;
    font-weight: 500;
    padding: 7px 18px;
    border-radius: 24px;
    cursor: pointer;
    transition: color var(--transition-fast);
    white-space: nowrap;
    display: flex;
    align-items: center;
    gap: 5px;
}

.mode-btn.active {
    color: #fff;
}

.mode-btn:hover:not(.active) {
    color: var(--text-primary);
}

.mode-icon {
    font-size: 0.9rem;
}

.mode-slider {
    position: absolute;
    top: 3px;
    left: 3px;
    height: calc(100% - 6px);
    width: calc(50% - 4px);
    background: var(--accent-gradient);
    border-radius: 24px;
    transition: transform var(--transition-normal);
    z-index: 1;
    box-shadow: var(--accent-glow);
}

.mode-slider.slide-right {
    transform: translateX(calc(100% + 2px));
}

/* 文章选择器 */
#article-select {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: var(--border-radius-sm);
    padding: 7px 12px;
    font-family: var(--font-cn);
    font-size: 0.82rem;
    cursor: pointer;
    outline: none;
    transition: border-color var(--transition-fast);
    max-width: 200px;
}

#article-select:focus {
    border-color: var(--accent-primary);
}

#article-select option {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

/* ============================
   Main / 双面板布局
   ============================ */
#app-main {
    flex: 1;
    display: flex;
    gap: var(--gap);
    padding: var(--gap);
    overflow: hidden;
    min-height: 0;
}

.panel {
    background: rgba(22, 24, 34, 0.6);
    border-radius: var(--border-radius);
    border: 1px solid rgba(255, 255, 255, 0.08);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    min-height: 0;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
}

.panel-left {
    flex: 6;
}

.panel-right {
    flex: 4;
}

/* 阅读模式：右侧面板隐藏，左侧全宽 */
body.mode-reading .panel-right {
    display: none;
}

body.mode-reading .panel-left {
    flex: 1;
}

.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 20px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    flex-shrink: 0;
}

.panel-header h2 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-secondary);
    font-family: var(--font-cn);
}

.panel-actions {
    display: flex;
    gap: 6px;
}

.icon-btn {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.08);
    color: var(--text-secondary);
    border-radius: 6px;
    padding: 4px 10px;
    font-size: 0.75rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

.panel-content {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    scroll-behavior: smooth;
}

/* 滚动条 */
.panel-content::-webkit-scrollbar {
    width: 6px;
}

.panel-content::-webkit-scrollbar-track {
    background: transparent;
}

.panel-content::-webkit-scrollbar-thumb {
    background: linear-gradient(to bottom, rgba(129, 140, 248, 0.2), rgba(167, 139, 250, 0.2));
    border-radius: 3px;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.panel-content::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(to bottom, rgba(129, 140, 248, 0.4), rgba(167, 139, 250, 0.4));
}

/* ============================
   句子渲染
   ============================ */
.paragraph-group {
    margin-bottom: 28px;
}

/* ============================
   阅读模式网格排版 (左英文，右中文)
   ============================ */
.paragraph-reading-grid {
    display: grid;
    grid-template-columns: 6fr 4fr;
    /* 左右 6:4 比例 */
    gap: 0;
    /* 移除外层 gap，交给内层 padding/border 处理分割线 */
    align-items: start;
}

.paragraph-translation-col {
    font-family: var(--font-cn);
    font-size: 0.95em;
    color: var(--text-translation);
    line-height: 1.8;
    padding: 12px 24px;
    margin-left: 24px;
    /* 与左栏间距 */
    border-radius: var(--border-radius-sm);
    background: rgba(28, 31, 46, 0.4);
    /* 稍微偏暗的背景以区分 */
    border-left: 1px solid rgba(255, 255, 255, 0.08);
    /* 中间的竖向分割线 */
}

.paragraph-translation-col .translation-sentence {
    cursor: pointer;
    transition: all var(--transition-fast);
    border-radius: 3px;
    padding: 1px 3px;
}

.paragraph-translation-col .translation-sentence:hover {
    background: rgba(165, 180, 252, 0.15);
}

.paragraph-translation-col .translation-sentence.active {
    background: rgba(129, 140, 248, 0.2);
    color: #fff;
    border-radius: 4px;
    padding: 2px 4px;
}

.paragraph-label {
    font-size: 0.7rem;
    color: var(--text-muted);
    font-family: var(--font-cn);
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* 段落内句子连续流排 */
.paragraph-flow {
    padding: 12px 16px;
    border-radius: var(--border-radius-sm);
    transition: background var(--transition-fast);
    line-height: 2.8;
}

/* 每个句子的 inline 包裹 */
.sentence-inline {
    display: inline;
    cursor: pointer;
    border-radius: 4px;
    transition: all var(--transition-fast);
    position: relative;
}

.sentence-inline:hover .word-text {
    color: var(--accent-primary);
}

.sentence-inline.active .word-text {
    color: #fbbf24;
}

.sentence-inline.active .word-phonetic {
    color: var(--accent-secondary);
    opacity: 1;
}

.sentence-inline.active {
    background: rgba(129, 140, 248, 0.1) !important;
    box-shadow: 0 0 15px rgba(129, 140, 248, 0.1) !important;
    border-radius: 6px;
    transition: all 0.3s ease;
}



.sentence-inline.playing .word-text {
    color: var(--color-success);
}

.sentence-inline.playing {
    position: relative;
}

.sentence-inline.playing::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--color-success);
    border-radius: 2px;
    animation: pulseWidth 2s infinite ease-in-out;
}

@keyframes pulseWidth {
    0% {
        opacity: 0.4;
        transform: scaleX(0.8);
    }

    50% {
        opacity: 1;
        transform: scaleX(1);
    }

    100% {
        opacity: 0.4;
        transform: scaleX(0.8);
    }
}

.sentence-spacer {
    display: inline;
    width: 6px;
}

/* 学习模式下，鼠标悬停也不再显示背景框 */
body.mode-learning .sentence-inline:hover {
    background: none;
}

/* 单词 + 音标对齐 */
.word-unit {
    display: inline-block;
    text-align: center;
    margin-right: 5px;
    vertical-align: top;
    line-height: 1;
    margin-bottom: 4px;
}

.word-text {
    display: block;
    font-family: var(--font-en);
    font-size: 1em;
    font-weight: 400;
    color: var(--text-primary);
    line-height: 1.4;
}

.word-phonetic {
    display: block;
    font-family: var(--font-en);
    font-size: 0.82em;
    color: var(--text-phonetic);
    line-height: 1.2;
    opacity: 0.85;
}

/* 句子编号 */
.sentence-id {
    display: none;
}

/* 右侧面板 - 译文 (阅读模式) 按段落分组 */
.translation-paragraph {
    font-family: var(--font-cn);
    font-size: 0.95em;
    color: var(--text-translation);
    line-height: 1.8;
    padding: 12px 16px;
    margin-bottom: 24px;
    border-radius: var(--border-radius-sm);
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.04);
}

.translation-sentence {
    cursor: pointer;
    transition: all var(--transition-fast);
    border-radius: 3px;
    padding: 1px 3px;
}

.translation-sentence:hover {
    background: rgba(165, 180, 252, 0.15);
}

.translation-sentence.active {
    background: rgba(129, 140, 248, 0.2);
    color: #fff;
    border-radius: 4px;
    padding: 2px 4px;
}

/* ============================
   右侧面板 - 分析 (学习模式)
   ============================ */
.analysis-container {
    animation: fadeSlideIn 0.35s ease;
}

@keyframes fadeSlideIn {
    from {
        opacity: 0;
        transform: translateY(12px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.analysis-section {
    margin-bottom: 20px;
}

.analysis-section-title {
    font-family: var(--font-cn);
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.analysis-section-title::before {
    content: '';
    display: inline-block;
    width: 3px;
    height: 14px;
    border-radius: 2px;
}

.section-long-sentence .analysis-section-title::before {
    background: var(--accent-primary);
}

.section-vocabulary .analysis-section-title::before {
    background: var(--color-vocab);
}

.section-phrases .analysis-section-title::before {
    background: var(--color-phrase);
}

/* 长难句分析文本 */
.long-sentence-text {
    font-family: var(--font-cn);
    font-size: 0.9em;
    color: var(--text-secondary);
    line-height: 1.8;
    padding: 12px 16px;
    background: var(--bg-card);
    border-radius: var(--border-radius-sm);
    border-left: 3px solid var(--accent-primary);
}

/* 词汇卡片 */
.vocab-card {
    background: var(--bg-card);
    border-radius: var(--border-radius-sm);
    padding: 12px 16px;
    margin-bottom: 8px;
    border: 1px solid rgba(255, 255, 255, 0.04);
    transition: all var(--transition-fast);
}

.vocab-card:hover {
    border-color: rgba(244, 114, 182, 0.4);
    transform: translateX(6px);
    box-shadow: 0 4px 20px rgba(244, 114, 182, 0.1);
}

.vocab-word {
    font-family: var(--font-en);
    font-size: 1em;
    font-weight: 600;
    color: var(--color-vocab);
}

.vocab-phonetic {
    font-family: var(--font-en);
    font-size: 0.8em;
    color: var(--text-muted);
    margin-left: 8px;
}

.vocab-meaning {
    font-family: var(--font-cn);
    font-size: 0.85em;
    color: var(--text-secondary);
    margin-top: 4px;
}

.vocab-context {
    font-family: var(--font-en);
    font-size: 0.78em;
    color: var(--text-muted);
    margin-top: 4px;
    font-style: italic;
}

/* 短语卡片 */
.phrase-card {
    background: var(--bg-card);
    border-radius: var(--border-radius-sm);
    padding: 10px 14px;
    margin-bottom: 6px;
    border: 1px solid rgba(255, 255, 255, 0.04);
    display: flex;
    align-items: baseline;
    gap: 12px;
    transition: all var(--transition-fast);
}

.phrase-card:hover {
    border-color: rgba(56, 189, 248, 0.2);
    transform: translateX(4px);
}

.phrase-text {
    font-family: var(--font-en);
    font-size: 0.92em;
    font-weight: 500;
    color: var(--color-phrase);
    white-space: nowrap;
}

.phrase-meaning {
    font-family: var(--font-cn);
    font-size: 0.85em;
    color: var(--text-secondary);
}

/* 学习模式原文预览 */
.analysis-original {
    font-family: var(--font-en);
    font-size: 0.88em;
    color: var(--text-primary);
    line-height: 1.7;
    padding: 12px 16px;
    background: var(--bg-card);
    border-radius: var(--border-radius-sm);
    margin-bottom: 16px;
    opacity: 0.9;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.analysis-translation {
    font-family: var(--font-cn);
    font-size: 0.85em;
    color: var(--text-translation);
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

/* ============================
   右侧面板 - 题目 (学习模式)
   ============================ */
.questions-container {
    animation: fadeSlideIn 0.35s ease;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.question-card {
    background: var(--bg-card);
    border-radius: var(--border-radius);
    padding: 14px;
    border: 1px solid rgba(255, 255, 255, 0.06);
    transition: all var(--transition-normal);
}

.question-card:hover {
    border-color: var(--accent-primary);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
}

.question-id {
    font-size: 0.7rem;
    color: var(--accent-primary);
    font-weight: 600;
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.question-title-box {
    margin-bottom: 12px;
    padding-bottom: 10px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.q-title-en {
    font-size: 1rem;
    color: var(--text-primary);
    line-height: 1.5;
    margin-bottom: 4px;
}

.q-title-ph {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 2px;
}

.q-title-cn {
    font-size: 0.85rem;
    color: var(--text-translation);
}

.options-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 8px;
}

.option-item {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 8px 14px;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.04);
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.option-item:hover {
    background: rgba(255, 255, 255, 0.06);
    border-color: rgba(255, 255, 255, 0.1);
    transform: translateX(4px);
}

.option-item.selected {
    background: var(--bg-highlight);
    border-color: var(--accent-primary);
    box-shadow: 0 0 15px rgba(129, 140, 248, 0.1);
}

.option-letter {
    width: 24px;
    height: 24px;
    background: var(--bg-secondary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--accent-secondary);
    flex-shrink: 0;
    transition: all var(--transition-fast);
    margin-top: 2px;
}

.option-item.selected .option-letter {
    background: var(--accent-gradient);
    color: #fff;
    border-color: transparent;
    box-shadow: var(--accent-glow);
}

.option-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.option-top-row {
    display: flex;
    justify-content: flex-start;
    align-items: baseline;
    gap: 12px;
}

.option-text {
    font-size: 0.95rem;
    color: var(--text-primary);
    font-weight: 600;
}

.option-ph {
    font-size: 0.78rem;
    color: var(--text-muted);
    font-family: var(--font-en);
}

.option-cn {
    font-size: 0.85rem;
    color: var(--text-translation);
    font-family: var(--font-cn);
}

/* ============================
   底部音频控制栏
   ============================ */
#audio-bar {
    height: var(--footer-height);
    background: rgba(22, 24, 34, 0.8);
    border-top: 1px solid rgba(255, 255, 255, 0.08);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    flex-shrink: 0;
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    transition: transform var(--transition-normal), opacity var(--transition-normal);
}

#audio-bar.hidden {
    transform: translateY(100%);
    opacity: 0;
    pointer-events: none;
    height: 0;
    padding: 0;
    border: none;
}

.audio-info {
    display: flex;
    flex-direction: column;
    gap: 2px;
    min-width: 0;
    flex: 1;
}

.audio-label {
    font-family: var(--font-cn);
    font-size: 0.8rem;
    color: var(--text-secondary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.audio-progress {
    font-size: 0.7rem;
    color: var(--text-muted);
}

.audio-controls {
    display: flex;
    align-items: center;
    gap: 8px;
}

.audio-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: none;
    background: var(--bg-card);
    color: var(--text-secondary);
    font-size: 0.9rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.audio-btn:hover {
    background: var(--bg-card-hover);
    color: var(--text-primary);
    transform: scale(1.08);
}

.audio-btn-play {
    width: 44px;
    height: 44px;
    background: var(--accent-gradient);
    color: #fff;
    font-size: 1.1rem;
    box-shadow: var(--accent-glow);
}

.audio-btn-play:hover {
    transform: scale(1.12);
    box-shadow: 0 0 30px rgba(129, 140, 248, 0.4);
}

.audio-btn.loop-active {
    color: var(--color-success);
    background: rgba(52, 211, 153, 0.15);
}

/* ============================
   占位提示
   ============================ */
.placeholder-msg {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    color: var(--text-muted);
    font-family: var(--font-cn);
    font-size: 0.95rem;
}

@media (max-width: 768px) {
    #app-main {
        flex-direction: column;
    }

    .panel-left,
    .panel-right {
        flex: 1;
    }

    .header-left h1 {
        max-width: 120px;
    }

    .mode-btn {
        font-size: 0.75rem;
        padding: 6px 12px;
    }
}