/* 基础变量定义 */
:root {
    --sidebar-width: 320px;
    --header-height: 60px;
    --border-color: #e1e4e8;
    --bg-primary: #ffffff;
    --bg-secondary: #f6f8fa;
    --bg-tertiary: #fafbfc;
    --text-primary: #24292e;
    --text-secondary: #586069;
    --text-muted: #6a737d;
    --link-color: #0366d6;
    --link-hover: #0256cc;
    --accent-color: #0366d6;
    --success-color: #28a745;
    --warning-color: #ffc107;
    --danger-color: #dc3545;
    --shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
    --shadow-hover: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);
    --radius: 6px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 暗色主题 */
[data-theme="dark"] {
    --border-color: #30363d;
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --text-primary: #f0f6fc;
    --text-secondary: #8b949e;
    --text-muted: #7d8590;
    --link-color: #58a6ff;
    --link-hover: #79c0ff;
    --accent-color: #58a6ff;
}

/* 基础重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    overflow: hidden;
}

/* 主应用布局 */
.app {
    display: flex;
    height: 100vh;
    width: 100vw;
}

/* 侧边栏样式 */
.sidebar {
    width: var(--sidebar-width);
    background-color: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: var(--transition);
    z-index: 100;
}

.sidebar.collapsed {
    margin-left: calc(-1 * var(--sidebar-width));
}

.sidebar-header {
    padding: 16px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--bg-tertiary);
}

.sidebar-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
}

.sidebar-controls {
    display: flex;
    gap: 8px;
}

.theme-toggle, .sidebar-toggle, .mobile-menu-btn {
    background: none;
    border: 1px solid var(--border-color);
    padding: 6px 10px;
    border-radius: var(--radius);
    cursor: pointer;
    color: var(--text-secondary);
    transition: var(--transition);
    font-size: 14px;
}

.theme-toggle:hover, .sidebar-toggle:hover, .mobile-menu-btn:hover {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    border-color: var(--accent-color);
}

.search-container {
    padding: 16px;
    border-bottom: 1px solid var(--border-color);
}

.search-input {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: 14px;
    transition: var(--transition);
}

.search-input:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(3, 102, 214, 0.1);
}

.file-tree-container {
    flex: 1;
    overflow-y: auto;
    padding: 8px 0;
}

.file-tree {
    padding: 0 8px;
}

.tree-item {
    margin: 2px 0;
}

.tree-node {
    display: flex;
    align-items: center;
    padding: 6px 8px;
    border-radius: var(--radius);
    cursor: pointer;
    color: var(--text-secondary);
    font-size: 14px;
    text-decoration: none;
    transition: var(--transition);
    user-select: none;
}

.tree-node:hover {
    background-color: var(--bg-primary);
    color: var(--text-primary);
}

.tree-node.active {
    background-color: var(--accent-color);
    color: white;
}

.tree-node.directory {
    font-weight: 500;
}

.tree-icon {
    margin-right: 8px;
    font-size: 12px;
    width: 16px;
    text-align: center;
}

.tree-children {
    margin-left: 20px;
    display: none;
}

.tree-children.expanded {
    display: block;
}

/* 主内容区 */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    position: relative;
}

.content-header {
    padding: 12px 24px;
    border-bottom: 1px solid var(--border-color);
    background-color: var(--bg-secondary);
    display: flex;
    align-items: center;
    gap: 16px;
    min-height: var(--header-height);
}

.mobile-menu-btn {
    display: none;
}

.breadcrumb {
    font-size: 14px;
    color: var(--text-secondary);
}

.content-area {
    flex: 1;
    overflow-y: auto;
    padding: 32px;
    position: relative;
}

.welcome-message {
    text-align: center;
    padding: 64px 32px;
    color: var(--text-secondary);
}

.welcome-message h1 {
    font-size: 32px;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(255, 255, 255, 0.9);
    display: none;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    z-index: 10;
}

[data-theme="dark"] .loading-overlay {
    background-color: rgba(13, 17, 23, 0.9);
}

.loading-overlay.show {
    display: flex;
}

.loader {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--accent-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 16px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Markdown 内容样式 - GitHub 风格 */
.markdown-content {
    max-width: none;
    line-height: 1.6;
    animation: fadeIn 0.3s ease-in;
}

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

.markdown-content h1,
.markdown-content h2,
.markdown-content h3,
.markdown-content h4,
.markdown-content h5,
.markdown-content h6 {
    margin-top: 24px;
    margin-bottom: 16px;
    font-weight: 600;
    line-height: 1.25;
    color: var(--text-primary);
}

.markdown-content h1 {
    font-size: 2em;
    padding-bottom: 0.3em;
    border-bottom: 1px solid var(--border-color);
}

.markdown-content h2 {
    font-size: 1.5em;
    padding-bottom: 0.3em;
    border-bottom: 1px solid var(--border-color);
}

.markdown-content h3 { font-size: 1.25em; }
.markdown-content h4 { font-size: 1em; }
.markdown-content h5 { font-size: 0.875em; }
.markdown-content h6 { font-size: 0.85em; }

.markdown-content p {
    margin-bottom: 16px;
    color: var(--text-primary);
}

.markdown-content a {
    color: var(--link-color);
    text-decoration: none;
}

.markdown-content a:hover {
    color: var(--link-hover);
    text-decoration: underline;
}

.markdown-content ul, .markdown-content ol {
    padding-left: 2em;
    margin-bottom: 16px;
}

.markdown-content li {
    margin-bottom: 4px;
}

.markdown-content blockquote {
    padding: 0 1em;
    color: var(--text-secondary);
    border-left: 0.25em solid var(--border-color);
    margin-bottom: 16px;
}

.markdown-content pre {
    padding: 16px;
    overflow: auto;
    font-size: 85%;
    line-height: 1.45;
    background-color: var(--bg-secondary);
    border-radius: var(--radius);
    margin-bottom: 16px;
    border: 1px solid var(--border-color);
}

.markdown-content code {
    padding: 0.2em 0.4em;
    margin: 0;
    font-size: 85%;
    background-color: var(--bg-secondary);
    border-radius: 3px;
    font-family: 'SFMono-Regular', 'Consolas', 'Liberation Mono', 'Menlo', monospace;
}

.markdown-content pre code {
    padding: 0;
    background-color: transparent;
}

.markdown-content table {
    border-spacing: 0;
    border-collapse: collapse;
    margin-bottom: 16px;
    width: 100%;
}

.markdown-content table th,
.markdown-content table td {
    padding: 6px 13px;
    border: 1px solid var(--border-color);
}

.markdown-content table th {
    font-weight: 600;
    background-color: var(--bg-secondary);
}

.markdown-content table tr:nth-child(2n) {
    background-color: var(--bg-tertiary);
}

/* KaTeX 样式调整 */
.katex {
    font-size: 1.1em;
}

.katex-display {
    margin: 20px 0;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        top: 0;
        left: 0;
        height: 100vh;
        z-index: 1000;
        transform: translateX(-100%);
        transition: transform 0.3s ease;
    }

    .sidebar.show {
        transform: translateX(0);
    }

    .sidebar.collapsed {
        margin-left: 0;
        transform: translateX(-100%);
    }

    .main-content {
        width: 100%;
    }

    .mobile-menu-btn {
        display: block;
    }

    .sidebar-toggle {
        display: none;
    }

    .content-area {
        padding: 16px;
    }
}

@media (max-width: 480px) {
    .content-area {
        padding: 8px;
    }

    .markdown-content h1 { font-size: 1.6em; }
    .markdown-content h2 { font-size: 1.3em; }
    .markdown-content h3 { font-size: 1.1em; }
}

/* 滚动条样式 */
.file-tree-container::-webkit-scrollbar,
.content-area::-webkit-scrollbar {
    width: 8px;
}

.file-tree-container::-webkit-scrollbar-track,
.content-area::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

.file-tree-container::-webkit-scrollbar-thumb,
.content-area::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

.file-tree-container::-webkit-scrollbar-thumb:hover,
.content-area::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* 打印样式 */
@media print {
    .sidebar,
    .content-header,
    .loading-overlay {
        display: none !important;
    }

    .main-content {
        width: 100% !important;
    }

    .content-area {
        padding: 0 !important;
        overflow: visible !important;
    }
}

/* 展开侧边栏按钮 */
.expand-sidebar-btn {
    position: fixed;
    top: 20px;
    left: 20px;
    z-index: 200;
    background: var(--accent-color);
    color: white;
    border: none;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    cursor: pointer;
    font-size: 16px;
    display: none;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.expand-sidebar-btn:hover {
    background: var(--link-hover);
    box-shadow: var(--shadow-hover);
}

.expand-sidebar-btn.show {
    display: flex;
}

/* 学科分组样式 */
.subject-item {
    margin: 4px 0;
}

.tree-node.subject {
    font-weight: 600;
    color: var(--text-primary);
    background-color: var(--bg-tertiary);
    border-radius: var(--radius);
    position: relative;
    padding: 10px 12px;
}

.tree-node.subject:hover {
    background-color: var(--accent-color);
    color: white;
}

.expand-icon {
    position: absolute;
    right: 12px;
    font-size: 12px;
    transition: var(--transition);
}

.subject-children {
    margin-left: 16px;
    margin-top: 4px;
    padding-left: 12px;
    border-left: 2px solid var(--border-color);
}

.subject-item.expanded .subject-children {
    display: block;
}

/* 当侧边栏折叠时显示展开按钮 */
.sidebar.collapsed ~ .main-content .expand-sidebar-btn,
.sidebar.collapsed + .expand-sidebar-btn {
    display: none; /* 先隐藏，通过JS控制 */
}

/* 更新现有样式以支持新结构 */
.tree-children {
    margin-left: 20px;
    display: none;
    margin-top: 2px;
}

.tree-children.expanded {
    display: block;
}

.subject-children {
    display: none;
    margin-top: 8px;
}

.subject-children.expanded {
    display: block;
}

/* 文件项在学科中的样式调整 */
.subject-children .tree-item {
    margin: 1px 0;
}

.subject-children .tree-node.file {
    padding: 4px 8px;
    font-size: 13px;
}

.subject-children .tree-node.directory {
    padding: 6px 8px;
    font-size: 14px;
}

/* 响应式更新 */
@media (max-width: 768px) {
    .expand-sidebar-btn {
        display: none !important;
    }
}

/* 学科选择器样式 */
.subject-selector {
    padding: 16px;
    border-bottom: 1px solid var(--border-color);
}

.subject-select {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
}

.subject-select:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(3, 102, 214, 0.1);
}

.subject-select option {
    background-color: var(--bg-primary);
    color: var(--text-primary);
}

/* 欢迎树状态 */
.welcome-tree {
    padding: 32px 16px;
    text-align: center;
    color: var(--text-secondary);
    font-style: italic;
}

/* 当前学科显示 */
.current-subject {
    padding: 8px 16px;
    background-color: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    font-weight: 600;
    color: var(--text-primary);
    display: none;
}

.current-subject.show {
    display: block;
}

.current-subject::before {
    content: "📚 ";
    margin-right: 6px;
}