/* 统一章节目录容器样式 */
:root {
    --chapters-panel-width: 260px;
    --chapters-mobile-height: 70vh;
    --chapters-transition: 0.3s ease;
    --chapters-backdrop: rgba(0, 0, 0, 0.5);
    --chapters-shadow-pc: 2px 0 10px rgba(0, 0, 0, 0.1);
    --chapters-shadow-mobile: 0 -4px 20px rgba(0, 0, 0, 0.15);
}

/* 响应式布局容器 */
.reader-layout {
    display: flex;
    gap: 20px;
    align-items: flex-start;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 0.3em;
}

.content-area {
    flex: 1;
    min-width: 0;
}

/* 移动端布局 */
@media (max-width: 767px) {
    .reader-layout {
        flex-direction: column;
        gap: 0;
    }
    
    .content-area {
        width: 100%;
    }
}

/* 基础容器 */
.chapters-menu {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1000;
    visibility: hidden;
    opacity: 0;
    transition: visibility var(--chapters-transition), opacity var(--chapters-transition);
    pointer-events: none;
}

.chapters-menu.active {
    visibility: visible;
    opacity: 1;
    pointer-events: auto;
}

/* PC端sticky定位 */
@media (min-width: 768px) {
    .chapters-menu.active {
        position: sticky;
        top: 20px;
    }
}

/* 背景遮罩 */
.chapters-backdrop {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--chapters-backdrop);
    cursor: pointer;
}

/* 章节面板基础样式 */
.chapters-panel {
    position: absolute;
    background: var(--bg-color, white);
    border: 1px solid var(--border-color, #e0e0e0);
    transition: transform var(--chapters-transition);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* 章节头部 */
.chapters-header {
    padding: 16px 20px;
    border-bottom: 1px solid var(--border-color, #e0e0e0);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-shrink: 0;
}

.chapters-header h3 {
    margin: 0;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-color, #333);
}

.chapters-header .panel-close-btn {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--text-color, #666);
    padding: 4px 8px;
    border-radius: 4px;
    transition: background-color 0.2s ease;
}

.chapters-header .panel-close-btn:hover {
    background-color: var(--hover-bg-color, #f5f5f5);
}

/* 章节内容区域 */
.chapters-content {
    flex: 1;
    overflow-y: auto;
    padding: 8px 0;
}

/* 章节项样式 */
.chapters-content .toc-item {
    display: block;
    padding: 12px 20px;
    color: var(--text-color, #333);
    text-decoration: none;
    border: none;
    background: none;
    width: 100%;
    text-align: left;
    cursor: pointer;
    transition: background-color 0.2s ease;
    font-size: 0.95rem;
    line-height: 1.4;
}

.chapters-content .toc-item:hover {
    background-color: var(--hover-bg-color, #f8f9fa);
}

.chapters-content .toc-item.active {
    background-color: var(--primary-color, #007bff);
    color: white;
}

/* PC端样式 (≥768px) - 同层布局 */
@media (min-width: 768px) {
    .chapters-menu {
        position: static;
        visibility: visible;
        opacity: 1;
        pointer-events: auto;
        width: auto;
        height: auto;
        display: none; /* 默认隐藏，通过 active 类控制显示 */
    }
    
    .chapters-menu.active {
        display: block;
    }
    
    .chapters-backdrop {
        display: none; /* PC端不显示遮罩 */
    }
    
    .chapters-panel {
        position: static;
        width: var(--chapters-panel-width);
        height: auto;
        min-height: calc(100vh - 140px);
        max-height: calc(100vh - 140px);
        transform: none;
        box-shadow: var(--chapters-shadow-pc);
    }
    
    .chapters-content {
        max-height: calc(100vh - 220px);
    }
}

/* 移动端样式 (<768px) */
@media (max-width: 767px) {
    .chapters-panel {
        bottom: 0;
        left: 0;
        width: 100%;
        max-height: var(--chapters-mobile-height);
        border-radius: 16px 16px 0 0;
        transform: translateY(100%);
        box-shadow: var(--chapters-shadow-mobile);
    }
    
    .chapters-menu.active .chapters-panel {
        transform: translateY(0);
        width: 98vw;
        margin: 0 1vw;
    }
    
    .chapters-header {
        padding: 20px 20px 16px;
    }
    
    .chapters-content .toc-item {
        padding: 16px 20px;
        font-size: 1rem;
    }
}

/* 滚动条样式 */
.chapters-content {
    scrollbar-width: thin;
    scrollbar-color: var(--scrollbar-thumb, #ccc) transparent;
}

.chapters-content::-webkit-scrollbar {
    width: 6px;
}

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

.chapters-content::-webkit-scrollbar-thumb {
    background-color: var(--scrollbar-thumb, #ccc);
    border-radius: 3px;
}

.chapters-content::-webkit-scrollbar-thumb:hover {
    background-color: var(--scrollbar-thumb-hover, #999);
}

/* 暗色模式适配 */
html.dark .chapters-panel {
    background: var(--bg-color);
    border-color: var(--border-color);
}

html.dark .chapters-header {
    border-bottom-color: var(--border-color);
}

html.dark .chapters-header h3 {
    color: var(--text-color);
}

html.dark .chapters-header .panel-close-btn {
    color: var(--text-color);
}

html.dark .chapters-header .panel-close-btn:hover {
    background-color: var(--hover-bg-color);
}

html.dark .chapters-content .toc-item {
    color: var(--text-color);
}

html.dark .chapters-content .toc-item:hover {
    background-color: var(--hover-bg-color);
}

html.dark .chapters-content {
    scrollbar-color: var(--scrollbar-thumb) transparent;
}

html.dark .chapters-content::-webkit-scrollbar-thumb {
    background-color: var(--scrollbar-thumb);
}

html.dark .chapters-content::-webkit-scrollbar-thumb:hover {
    background-color: var(--scrollbar-thumb-hover);
}