/* ========== CSS 变量 - 线装古籍书卷 · 朱墨双色典雅主题 ========== */
:root {
    /* 陈年熟宣与古旧案案木雕的温馨渐变，叠加微弱的宣纸墨粒肌理 */
    --color-bg-gradient: linear-gradient(135deg, #e6dcce 0%, #cbbaa4 100%);
    --color-bg-dots: radial-gradient(rgba(60, 47, 47, 0.05) 1.5px, transparent 1.5px);
    
    --color-card-bg: #fbf9f5;        /* 熟宣白：古朴温润、带有纸张质感的古籍页底色 */
    --color-text: #3c2f2f;           /* 松烟墨：徽墨色，带有些许暖褐墨韵的极深墨色，极易阅读 */
    --color-text-light: #7c6c62;     /* 赭石/浅褐：二级文字与旁批色 */
    --color-primary: #a63f32;        /* 朱砂红：古典朱红印泥色，极为典雅 */
    --color-primary-light: #f5eedc;  /* 暖竹白：古籍交互与悬停底色 */
    --color-dark: #20130e;           /* 乌木黑：用于标题与重要印刻文字 */
    --color-border: #dacdb6;         /* 宣纸淡金分割线 */
    --color-border-dark: #7c6252;    /* 檀木褐：古籍版框线色 */
    
    /* 强制古籍采用宋体/明体，一秒呈现书卷木刻雕版气 */
    --font-serif: "Source Han Serif CN", "Noto Serif CJK SC", "Songti SC", "STSong", "SimSun", serif;
    --font-sans: "Source Han Serif CN", "Noto Serif CJK SC", "Songti SC", "STSong", "SimSun", serif;
    
    /* 古籍的规整与硬朗线条 */
    --radius-sm: 2px;
    --radius-md: 4px;
    --radius-lg: 6px;
    --radius-circle: 50%;
    
    --shadow-sm: 0 4px 10px rgba(124, 98, 82, 0.04);
    --shadow-md: 0 8px 24px rgba(124, 98, 82, 0.1);
    --shadow-lg: 0 20px 50px rgba(32, 19, 14, 0.15); /* 悬浮卡片的重力投影 */
}

/* ========== 基础重置 ========== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
    -webkit-user-select: none;
    user-select: none;
}

/* 页面大背景 */
body {
    font-family: var(--font-serif);
    background-color: #cbbaa4;
    /* 宣纸颗粒度与古朴渐变 */
    background-image: var(--color-bg-dots), var(--color-bg-gradient);
    background-size: 20px 20px, cover;
    background-attachment: fixed;
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    -webkit-font-smoothing: antialiased;
}

/* ========== App 容器 (线装书双边版框设计) ========== */
.app-container {
    width: 100%;
    max-width: 460px;
    height: 100vh;
    height: 100dvh;
    background-color: var(--color-card-bg);
    position: relative;
    display: flex;
    flex-direction: column;
    box-shadow: none;
    transition: all 0.3s ease;
}

/* 屏幕较宽时呈现悬浮古籍书页形态，增加双重版框线 */
@media (min-width: 481px) {
    .app-container {
        border-radius: var(--radius-lg);
        height: 90vh;
        height: 90dvh;
        max-height: 850px;
        box-shadow: var(--shadow-lg);
        /* 双边线装书装订边框效果 */
        border: 4px double var(--color-border-dark);
        padding: 4px;
        background-color: var(--color-card-bg);
    }
}

/* ========== 顶部导航栏 ========== */
.app-header {
    display: flex;
    align-items: center;
    padding: 16px 20px;
    background-color: var(--color-card-bg);
    border-bottom: 2px solid var(--color-border-dark); /* 版框边线 */
    position: sticky;
    top: 0;
    z-index: 100;
}

/* 返回按钮：宛如一方古典朱砂私印 */
.btn-back {
    width: 38px;
    height: 38px;
    border: 2px solid var(--color-primary);
    background: var(--color-card-bg);
    color: var(--color-primary);
    cursor: pointer;
    border-radius: var(--radius-circle);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-sm);
    transition: all 0.2s cubic-bezier(0.25, 1, 0.5, 1);
    flex-shrink: 0;
}

.btn-back:active {
    background-color: var(--color-primary-light);
    transform: scale(0.9);
}

.app-title {
    flex: 1;
    text-align: center;
    font-family: var(--font-serif);
    font-size: 18px;
    font-weight: 700;
    color: var(--color-primary); /* 朱红刊刻标题 */
    letter-spacing: 0.15em; /* 较宽的古典字距 */
}

.header-spacer {
    width: 38px;
    flex-shrink: 0;
    display: none;
}

/* ========== 主内容区域 ========== */
.app-main {
    flex: 1;
    padding: 20px 16px;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
}

.view {
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(4px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ========== 第一级：单行分类列表 (宣纸书签签条风格) ========== */
.categories-grid {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.category-card {
    background: var(--color-card-bg);
    border-radius: var(--radius-sm);
    padding: 18px 20px;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border-dark); /* 檀木单线框 */
    border-left: 6px solid var(--color-primary); /* 朱红色书签签条感 */
    transition: all 0.25s cubic-bezier(0.25, 0.8, 0.25, 1);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.category-card:active {
    background-color: var(--color-primary-light);
    transform: scale(0.99) translateY(-1px);
    box-shadow: var(--shadow-md);
}

.category-info-meta {
    display: flex;
    flex-direction: column;
    gap: 3px;
}

.category-name {
    font-family: var(--font-serif);
    font-size: 16px;
    font-weight: 700;
    color: var(--color-dark);
    letter-spacing: 0.05em;
}

.category-count {
    font-size: 12px;
    color: var(--color-text-light);
    font-weight: 500;
}

.category-chevron {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--color-text-light);
}

/* ========== 第二级：主题列表 ========== */
.topics-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.topic-item {
    background: var(--color-card-bg);
    border-radius: var(--radius-sm);
    padding: 16px 20px;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border-dark);
    transition: all 0.25s ease;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.topic-item:active {
    background-color: var(--color-primary-light);
}

.topic-info {
    flex: 1;
}

.topic-name {
    font-family: var(--font-serif);
    font-size: 15px;
    font-weight: 700;
    color: var(--color-dark);
    letter-spacing: 0.04em;
}

.topic-lecture-count {
    font-size: 12px;
    color: var(--color-text-light);
    font-weight: 500;
    margin-top: 2px;
}

.topic-arrow {
    color: var(--color-text-light);
    display: flex;
    align-items: center;
}

/* ========== 第三级：播放器面板 ========== */
.player-card {
    background: var(--color-card-bg);
    border-radius: var(--radius-sm);
    padding: 24px 20px 20px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border-dark);
    margin-bottom: 16px;
}

.player-info {
    text-align: center;
    margin-bottom: 20px;
    border-bottom: 1px dashed var(--color-border);
    padding-bottom: 14px;
}

.player-lecture-title {
    font-family: var(--font-serif);
    font-size: 17px;
    font-weight: 700;
    color: var(--color-dark);
    letter-spacing: 0.05em;
}

.player-topic-name {
    font-size: 12px;
    color: var(--color-text-light);
    font-weight: 500;
    margin-top: 6px;
}

/* 进度条 */
.player-progress-container {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 22px;
}

.player-time {
    font-size: 11px;
    color: var(--color-text-light);
    font-weight: 500;
    font-variant-numeric: tabular-nums;
    min-width: 36px;
    text-align: center;
}

.player-progress-bar {
    flex: 1;
    height: 3px;
    background: #e6dfd5;
    border-radius: var(--radius-sm);
    position: relative;
    cursor: pointer;
}

.player-progress-fill {
    height: 100%;
    background: var(--color-primary);
    border-radius: var(--radius-sm);
    width: 0%;
}

.player-progress-thumb {
    position: absolute;
    top: 50%;
    width: 10px;
    height: 10px;
    background: var(--color-primary);
    border: 1px solid var(--color-card-bg);
    border-radius: var(--radius-circle);
    transform: translate(-50%, -50%);
    left: 0%;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
    pointer-events: none;
}

/* 控制按键 */
.player-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 28px;
    margin-bottom: 22px;
}

.btn-control {
    border: none;
    background: none;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
    color: var(--color-text);
    transition: all 0.15s ease;
}

.btn-control:active {
    transform: scale(0.9);
}

/* 播放暂停：正圆朱砂红章造型 */
.btn-play-pause {
    width: 58px;
    height: 58px;
    background: var(--color-primary);
    border-radius: var(--radius-circle);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-card-bg);
    box-shadow: 0 4px 10px rgba(166, 63, 50, 0.2);
    transition: all 0.2s ease;
}

.btn-play-pause:active {
    transform: scale(0.92);
    background-color: #8c3226;
}

.btn-label {
    font-size: 10px;
    color: var(--color-text-light);
    font-weight: 600;
}

/* 倍速面板 */
.player-speed-controls {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding-top: 14px;
    border-top: 1px dashed var(--color-border-dark);
}

.speed-label {
    font-size: 11px;
    color: var(--color-text-light);
    font-weight: 600;
}

.speed-buttons {
    display: flex;
    gap: 5px;
}

.btn-speed {
    padding: 5px 12px;
    border: 1px solid var(--color-border-dark);
    background: var(--color-card-bg);
    border-radius: var(--radius-sm);
    font-size: 11px;
    font-weight: 600;
    color: var(--color-text);
    cursor: pointer;
    transition: all 0.15s ease;
}

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

.btn-speed.active {
    background: var(--color-primary);
    color: var(--color-card-bg);
    border-color: var(--color-primary);
}

/* ========== 本主题讲座列表 ========== */
.player-lecture-list {
    background: var(--color-card-bg);
    border-radius: var(--radius-sm);
    padding: 18px 16px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border-dark);
}

.list-title {
    font-family: var(--font-serif);
    font-size: 13px;
    font-weight: 700;
    color: var(--color-dark);
    margin-bottom: 12px;
    padding: 0 8px;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.lecture-items {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.lecture-item {
    padding: 11px 14px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 14px;
    color: var(--color-text);
}

.lecture-item:active {
    background-color: var(--color-bg);
}

.lecture-item.playing {
    background-color: var(--color-primary-light);
    color: var(--color-primary);
    font-weight: 700;
}

.lecture-item-icon {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--color-primary);
    flex-shrink: 0;
    opacity: 0;
    transition: opacity 0.2s;
}

.lecture-item.playing .lecture-item-icon {
    opacity: 1;
    animation: pulse 1.5s ease-in-out infinite;
}

/* ========== 已听完（朱砂朱拓打勾） ========== */
.lecture-item.is-read {
    color: var(--color-text-light) !important;
}

.lecture-item.is-read::after {
    content: "✓";
    font-size: 12px;
    color: var(--color-primary); /* 朱拓朱记印记 */
    margin-left: auto;
    font-weight: bold;
}

.lecture-item.playing.is-read {
    color: var(--color-primary) !important;
}

.lecture-item.playing.is-read::after {
    display: none;
}

/* “新”徽章样式 (朱砂印纸条徽标) */
.update-badge {
    display: inline-block;
    background-color: var(--color-primary);
    color: var(--color-card-bg);
    font-size: 9px;
    font-weight: 700;
    padding: 2px 5px;
    border-radius: var(--radius-sm);
    line-height: 1;
}

.update-tag {
    display: inline-block;
    background-color: var(--color-primary);
    color: var(--color-card-bg);
    font-size: 9px;
    font-weight: 700;
    padding: 2px 5px;
    border-radius: var(--radius-sm);
    line-height: 1;
    margin-left: 6px;
    vertical-align: middle;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); opacity: 1; }
    50% { transform: scale(1.4); opacity: 0.5; }
}

/* ========== 响应式微调 ========== */
@media (max-width: 360px) {
    .category-card {
        padding: 16px 18px;
    }
    .player-controls {
        gap: 20px;
    }
}