:root {
  --bg: #F5F3EF;
  --surface: #FFFFFF;
  --border: #E5DFD7;
  --border-light: #EDE8E2;
  --text: #1C1814;
  --text-dim: #7B7268;
  --accent: #5A8EC9;
  --accent-hover: #4A7EB5;
  --accent-light: rgba(90, 142, 201, 0.09);
  --highlight: #C53030;
  --green: #059669;
  --sidebar-width: 260px;
  --content-width: 380px;
  --resizer-size: 5px;
}

* {
  box-sizing: border-box;
}

/* 精致滚动条 */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-dim); }

html, body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  font-family: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
}

/* ── 导航栏 ─────────────────────────────────── */
.top-nav {
  display: flex;
  align-items: center;
  padding: 0 1.25rem;
  height: 46px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  font-size: 0.875rem;
  flex-shrink: 0;
  gap: 0.2rem;
}

.top-nav .nav-item {
  color: var(--text-dim);
  text-decoration: none;
  padding: 0.3rem 0.65rem;
  border-radius: 6px;
  transition: background 0.15s, color 0.15s;
  font-weight: 450;
}

.top-nav .nav-item:hover {
  background: var(--accent-light);
  color: var(--accent);
}

.top-nav .nav-item.active {
  color: var(--text);
  font-weight: 600;
  cursor: default;
}

.top-nav .nav-item.active:hover {
  background: transparent;
  color: var(--text);
}

.top-nav .nav-sep {
  color: var(--border);
  user-select: none;
  margin: 0 0.1rem;
}

.top-nav .nav-user-area {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.top-nav .nav-username {
  font-size: 0.85rem;
  color: var(--text-dim);
}

.top-nav .nav-logout {
  font-size: 0.83rem;
  color: var(--text-dim);
  text-decoration: none;
  padding: 0.22rem 0.6rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  transition: color 0.15s, border-color 0.15s;
}

.top-nav .nav-logout:hover {
  color: #c0392b;
  border-color: #c0392b;
}

/* ── 主布局 ─────────────────────────────────── */
.app {
  display: grid;
  grid-template-columns: var(--sidebar-width) var(--resizer-size) 1fr var(--resizer-size) var(--content-width);
  grid-template-rows: 1fr;
  flex: 1;
  min-height: 0;
  overflow: hidden;
}

.resizer {
  background: var(--border-light);
  cursor: col-resize;
  flex-shrink: 0;
  transition: background 0.2s;
  position: relative;
}

/* 扩大可点击区域 */
.resizer::after {
  content: '';
  position: absolute;
  inset: 0 -3px;
}

.resizer:hover,
.resizer:active {
  background: var(--accent);
}

.resizer-sidebar { grid-column: 2; }
.resizer-content { grid-column: 4; }

/* ── 侧边栏 ─────────────────────────────────── */
.sidebar {
  background: var(--surface);
  border-right: 1px solid var(--border);
  min-height: 0;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.sidebar-header {
  flex-shrink: 0;
  padding: 0.875rem 1rem 0.75rem;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
}

.sidebar-header label {
  font-size: 0.69rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
}

.source-select {
  width: 100%;
  padding: 0.45rem 2rem 0.45rem 0.7rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 7px;
  color: var(--text);
  font-size: 0.875rem;
  font-family: inherit;
  cursor: pointer;
  transition: border-color 0.2s, box-shadow 0.2s;
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 10 10'%3E%3Cpath fill='%237B7268' d='M5 7L1 3h8z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.65rem center;
}

.source-select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(90, 142, 201, 0.15);
}

/* ── 文件树 ─────────────────────────────────── */
.file-tree {
  flex: 1;
  min-height: 0;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 0.35rem 0;
  font-size: 0.84rem;
}

.file-tree.empty-state {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  color: var(--text-dim);
  font-size: 0.875rem;
}

.file-tree-row {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.38rem 0.85rem;
  cursor: pointer;
  white-space: nowrap;
  user-select: none;
  transition: background 0.1s;
  position: relative;
}

.file-tree-row:hover {
  background: var(--accent-light);
}

.file-tree-row.file-tree-folder .file-tree-label,
.file-tree-row.file-tree-document .file-tree-label {
  flex: 1;
  font-weight: 500;
}

.file-tree-row.file-tree-page {
  font-size: 0.82rem;
  color: var(--text-dim);
}

.file-tree-row.file-tree-page.selected {
  background: var(--accent-light);
  color: var(--accent);
  font-weight: 500;
}

/* 选中指示条 */
.file-tree-row.file-tree-page.selected::before {
  content: '';
  position: absolute;
  left: 0;
  top: 4px;
  bottom: 4px;
  width: 2px;
  background: var(--accent);
  border-radius: 0 2px 2px 0;
}

.file-tree-row.file-tree-error {
  color: var(--highlight);
  cursor: default;
  font-size: 0.8em;
}

/* 用 CSS 覆盖 JS 写入的 ▶ 字符 */
.file-tree-toggle {
  flex-shrink: 0;
  width: 1em;
  text-align: center;
  font-size: 0;
  color: var(--text-dim);
}

.file-tree-toggle::before {
  content: "›";
  font-size: 14px;
  display: block;
  line-height: 1;
  color: var(--text-dim);
  transition: transform 0.18s ease;
}

.file-tree-toggle.collapsed::before {
  transform: rotate(0deg);
}

.file-tree-toggle.expanded::before {
  transform: rotate(90deg);
}

.file-tree-toggle.leaf {
  visibility: hidden;
}

.file-tree-label {
  overflow: hidden;
  text-overflow: ellipsis;
}

.file-tree-children {
  border-left: 1px solid var(--border-light);
  margin-left: 1.3rem;
}

/* ── 主图像区 ───────────────────────────────── */
.main {
  padding: 1.5rem;
  min-height: 0;
  overflow: auto;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  background: var(--bg);
  position: relative;
}

.image-wrap {
  position: relative;
  display: inline-block;
  line-height: 0;
  box-shadow:
    0 0 0 1px var(--border),
    0 4px 20px rgba(0, 0, 0, 0.07),
    0 1px 4px rgba(0, 0, 0, 0.03);
  border-radius: 8px;
  overflow: hidden;
}

#page-image {
  max-width: 100%;
  height: auto;
  vertical-align: middle;
  display: block;
}

.overlay {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  pointer-events: auto;
  cursor: pointer;
}

/* 图片右上角覆盖 UI（水印比例 + 原图/最佳选项卡） */
.image-overlay-ui {
  position: absolute;
  top: 8px;
  right: 8px;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 5px;
  z-index: 20;
  pointer-events: auto;
}

.watermark-badge-wrap {
  background: rgba(30, 30, 30, 0.72);
  color: #fff;
  padding: 2px 7px;
  border-radius: 4px;
  font-size: 11px;
  line-height: 1.6;
  white-space: nowrap;
  pointer-events: none;
}

.watermark-badge-wrap.has-watermark {
  background: rgba(200, 40, 40, 0.78);
}

.image-tabs {
  display: flex;
  gap: 3px;
}

.tab-btn {
  padding: 3px 11px;
  border: 1px solid rgba(255,255,255,0.3);
  border-radius: 4px;
  cursor: pointer;
  font-size: 12px;
  background: rgba(30, 30, 30, 0.65);
  color: #fff;
  transition: background 0.15s;
}

.tab-btn:hover {
  background: rgba(80, 80, 80, 0.85);
}

.tab-btn.active {
  background: rgba(247, 118, 142, 0.9);
  border-color: rgba(247, 118, 142, 0.5);
}

/* 空状态 */
.viewer-empty-state {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.7rem;
  pointer-events: none;
  text-align: center;
}

.main:has(#page-image[src]:not([src=""])) .viewer-empty-state {
  display: none;
}

.viewer-empty-icon {
  width: 52px;
  height: 52px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 13px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
  margin-bottom: 0.15rem;
}

.viewer-empty-text {
  font-size: 0.925rem;
  color: var(--text);
  font-weight: 500;
}

.viewer-empty-sub {
  font-size: 0.78rem;
  color: var(--text-dim);
  max-width: 220px;
  line-height: 1.5;
}

/* ── 右侧内容面板 ───────────────────────────── */
.content-panel {
  background: var(--surface);
  border-left: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  min-height: 0;
  overflow: hidden;
}

.content-header {
  padding: 0.825rem 1.1rem;
  font-size: 0.69rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  flex-shrink: 0;
  gap: 0.5rem;
}

.content-header .hint {
  font-weight: 400;
  text-transform: none;
  letter-spacing: 0;
  font-size: 0.75rem;
  margin-left: auto;
  opacity: 0.7;
}

.page-meta-badge {
  display: none;
  align-items: center;
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: none;
  line-height: 1.6;
  white-space: normal;
  word-break: break-word;
}
.page-meta-badge.visible {
  display: inline-flex;
}
.page-meta-fitz {
  background: #deeeff;
  color: #1a6abf;
  border: 1px solid #a8ccf0;
}
.page-meta-ppstructure {
  background: #fff2e0;
  color: #b85c00;
  border: 1px solid #f0c890;
}

.content {
  flex: 1;
  overflow-y: auto;
  overflow-x: auto;
  min-width: 0;
  padding: 0.6rem 0.75rem;
  font-size: 0.875rem;
  line-height: 1.65;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.content .segment {
  display: block;
  padding: 0.38rem 0.6rem;
  margin-bottom: 0.15rem;
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.1s, border-color 0.1s;
  border-left: 2px solid transparent;
}

.content .segment:hover {
  background: var(--accent-light);
  border-left-color: var(--accent);
}

.content .segment.highlighted {
  background: rgba(197, 48, 48, 0.07);
  border-left: 3px solid var(--highlight);
}

.content .segment.empty {
  color: var(--text-dim);
  font-style: italic;
  cursor: default;
  font-size: 0.8rem;
  opacity: 0.7;
}

.content .segment .math,
.content .segment .katex {
  font-size: 1.05em;
}

.content .segment p {
  margin: 0;
}

.content .segment h2.md-heading,
.content .segment h3.md-heading,
.content .segment h4.md-heading {
  margin: 0;
  font-weight: 600;
  line-height: 1.4;
}

.content .segment h2.md-heading { font-size: 1.05rem; }
.content .segment h3.md-heading { font-size: 0.95rem; }
.content .segment h4.md-heading { font-size: 0.88rem; }

.content .segment .md-formula {
  text-align: center;
  overflow-x: auto;
  padding: 0.25rem 0;
}

.content .segment .md-table {
  overflow-x: auto;
  width: 100%;
}

.content .segment .md-table table,
.content .segment table {
  border-collapse: collapse;
  font-size: 0.83rem;
  width: 100%;
}

.content .segment .md-table td,
.content .segment .md-table th,
.content .segment td,
.content .segment th {
  border: 1px solid var(--border);
  padding: 0.3rem 0.55rem;
  text-align: left;
}

.content.empty-state {
  color: var(--text-dim);
  font-size: 0.875rem;
  padding: 1.5rem;
}

#page-image:not([src]),
#page-image[src=""] {
  min-height: 200px;
  background: var(--surface);
}