:root {
  --bg: #ffffff;
  --ink: #1a1a1a;
  --muted: #8a8a8a;
  --line: #ececec;
  --soft: #f7f7f7;
  --accent: #1a1a1a;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(0,0,0,.05), 0 8px 24px rgba(0,0,0,.06);
}
* { box-sizing: border-box; }
/* Covers are <img> tags: never let them start native image-drags
   (those mimic file drops and summon the import overlay). */
img { -webkit-user-drag: none; user-select: none; }
html, body { height: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: 'Inter', 'Segoe UI', system-ui, -apple-system, sans-serif;
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
}
#app { height: 100vh; display: flex; flex-direction: column; }

/* Top bar — one search field, nothing else. */
#topbar {
  display: flex; align-items: center; justify-content: center;
  padding: 10px 22px;
  background: #fff;
  user-select: none;
}
/* The field itself is invisible at rest — it reads as part of the page — and
   only draws itself in when you point at it or start typing. */
#searchInput {
  width: min(460px, 60vw);
  padding: 9px 14px;
  border: 1px solid transparent;
  border-radius: 999px;
  background: transparent;
  outline: none;
  font-size: 14px;
  color: var(--ink);
  text-align: center;
  transition: background .13s ease, border-color .13s ease, box-shadow .13s ease;
}
#searchInput::placeholder { color: #bdbdbd; }
#searchInput:focus {
  background: var(--soft);
  border-color: var(--line);
  box-shadow: 0 1px 2px rgba(0,0,0,.04);
  text-align: left;
}

/* Buttons */
.btn {
  border: 1px solid var(--line);
  background: #fff;
  padding: 8px 14px;
  border-radius: 999px;
  font-size: 13.5px;
  cursor: pointer;
  transition: all .15s ease;
  white-space: nowrap;
}
.btn:hover { border-color: #d4d4d4; background: var(--soft); }
.btn.primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn.primary:hover { opacity: .88; }
.icon-btn {
  border: 1px solid var(--line); background: #fff; border-radius: 8px;
  padding: 5px 10px; cursor: pointer; font-size: 13px;
}
.icon-btn:hover { background: var(--soft); }

/* Library */
#libraryView { flex: 1; overflow-y: auto; padding: 18px 28px 60px; position: relative; }
#breadcrumbRow { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; margin: 4px 0 6px; }
#breadcrumb { font-size: 13px; color: var(--muted); }
#breadcrumb b { color: var(--ink); font-weight: 650; }
#breadcrumb .crumb { cursor: pointer; }
#breadcrumb .crumb:hover { color: var(--ink); text-decoration: underline; }
#libHint { font-size: 12px; color: #b5b5b5; }
.section-title { font-size: 13px; font-weight: 650; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); margin: 18px 0 12px; }

#shelfGrid { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 12px; }
.folder-card {
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 14px 14px 12px 18px; background: #fff; cursor: pointer;
  transition: box-shadow .15s, transform .15s, border-color .15s;
  position: relative; overflow: hidden;
  user-select: none;
}
.folder-card:hover { box-shadow: var(--shadow); transform: translateY(-1px); }
.folder-card.dragover { border-color: #1a1a1a; box-shadow: 0 0 0 2px #1a1a1a inset; }
.folder-name { font-weight: 600; font-size: 14px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.folder-count { font-size: 12px; color: var(--muted); margin-top: 8px; }
.folder-bar { position: absolute; left: 0; top: 0; bottom: 0; width: 4px; }

/* Compact book tiles: folder-like cards, one book each, draggable. */
.book-tile {
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 12px; background: #fff; cursor: pointer;
  display: flex; gap: 11px; align-items: center;
  transition: box-shadow .15s, transform .15s;
  user-select: none; overflow: hidden; position: relative;
}
.book-tile:hover { box-shadow: var(--shadow); transform: translateY(-1px); }
.shelf-thumb {
  width: 46px; height: 64px; border-radius: 7px; object-fit: cover; flex: none;
  background: var(--soft); display: flex; align-items: center; justify-content: center;
  font-size: 22px; overflow: hidden;
}
.shelf-meta { min-width: 0; flex: 1; }
.shelf-title { font-weight: 600; font-size: 13.5px; line-height: 1.35; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.shelf-sub { font-size: 12px; color: var(--muted); margin-top: 4px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

#booksGrid { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 14px; }
.book-card {
  border: 1px solid var(--line); border-radius: var(--radius);
  background: #fff; overflow: hidden; cursor: pointer;
  transition: box-shadow .15s, transform .15s;
  user-select: none;
}
.book-card:hover { box-shadow: var(--shadow); transform: translateY(-2px); }
.book-card.dragging { opacity: .45; }
.book-cover {
  height: 190px; background: var(--soft);
  display: flex; align-items: center; justify-content: center;
  font-size: 44px; overflow: hidden; position: relative;
}
.book-cover img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; display: block; background: var(--soft); }
/* A cover smaller than its box would smear when stretched: show it 1:1. */
.book-cover img.cover-tiny, #audioCover img.cover-tiny {
  position: static; inset: auto; width: auto; height: auto;
  max-width: 100%; max-height: 100%; object-fit: contain; background: transparent;
}
.book-cover.audio { background: #fafafa; }
.type-badge {
  position: absolute; top: 8px; left: 8px;
  font-size: 10.5px; font-weight: 700; letter-spacing: .04em; text-transform: uppercase;
  background: rgba(255,255,255,.92); border: 1px solid var(--line);
  padding: 3px 8px; border-radius: 999px;
}
.book-meta { padding: 10px 11px 12px; }
.book-title { font-size: 13.5px; font-weight: 600; line-height: 1.35; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; min-height: 36px; }
.book-sub { font-size: 12px; color: var(--muted); margin-top: 4px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.progress-track { height: 3px; background: #f0f0f0; border-radius: 99px; margin-top: 8px; overflow: hidden; }
.progress-fill { height: 100%; background: #1a1a1a; width: 0%; }

#emptyState { text-align: center; padding: 56px 20px; border: 1.5px dashed var(--line); border-radius: 18px; margin-top: 6px; background: #fff; }
.empty-title { font-size: 20px; font-weight: 700; letter-spacing: -0.01em; }
.empty-sub { color: var(--muted); font-size: 14px; margin-top: 8px; line-height: 1.6; }
.empty-actions { display: flex; gap: 10px; justify-content: center; margin-top: 18px; }

/* Drop overlay */
#dropOverlay {
  position: fixed; inset: 0; z-index: 60;
  background: rgba(255,255,255,.86);
  display: flex; align-items: center; justify-content: center;
  pointer-events: none;
}
#dropOverlay.hidden { display: none; }
.drop-box { border: 2px dashed #cfcfcf; border-radius: 22px; padding: 60px 90px; text-align: center; background: #fff; }
.drop-title { font-size: 20px; font-weight: 700; }
.drop-sub { color: var(--muted); font-size: 13px; margin-top: 6px; }

.topbar-btn {
  flex: 0 0 auto; border: 1px solid transparent; background: transparent;
  color: var(--muted); font-size: 13.5px; padding: 8px 12px; border-radius: 999px;
  cursor: pointer; white-space: nowrap;
}
.topbar-btn:hover { color: var(--ink); background: var(--soft); }

/* Reader */
#readerView { flex: 1; display: flex; flex-direction: column; min-height: 0; position: relative; }
#readerView.hidden { display: none; }
#readerBar {
  display: flex; align-items: center; gap: 14px;
  padding: 12px 20px; border-bottom: 1px solid var(--line); background: #fff;
}
#readerTitleWrap { flex: 1; min-width: 0; }
#readerTitle { font-weight: 700; font-size: 15px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
#readerMeta { font-size: 12px; color: var(--muted); }
#readerControls .font-group { display: flex; align-items: center; gap: 7px; }

/* Phone: the reader bar has more controls than fits, so the title keeps the
   top row and the controls scroll sideways underneath it — otherwise Clean and
   Full end up off-screen where they cannot be tapped. */
@media (max-width: 620px) {
  #readerBar { flex-wrap: wrap; gap: 8px; padding: 10px 14px; }
  #readerTitleWrap { flex: 1 1 auto; order: 1; }
  #readerBar > #btnBack { order: 0; }
  #readerBar > #btnClean, #readerBar > #btnFullscreen { order: 2; }
  #readerControls {
    order: 3; flex: 1 0 100%; overflow-x: auto; overflow-y: hidden;
    -webkit-overflow-scrolling: touch; padding-bottom: 2px;
  }
  #readerControls .font-group, #readerControls .hidden { display: flex; }
  #readerControls .hidden { display: none !important; }
  #chapterNav { padding: 8px 12px; overflow-x: auto; flex-wrap: nowrap; }
  #epubContent { padding: 26px 18px 90px; }
}
#fontSizeLabel { font-size: 12px; color: var(--muted); min-width: 38px; text-align: center; }
#readerControls select { border: 1px solid var(--line); border-radius: 8px; padding: 6px 8px; font-size: 13px; background: #fff; }

#epubScroll { flex: 1; overflow-y: auto; background: #fff; }
#epubScroll.hidden { display: none; }
#epubContent {
  max-width: 700px; margin: 0 auto; padding: 44px 28px 120px;
  color: #222;
  transition: font-size .1s;
}
#epubContent img { max-width: 100%; height: auto; border-radius: 6px; }
#epubContent p { margin: 0 0 1em; }
#epubContent h1, #epubContent h2, #epubContent h3 { line-height: 1.25; margin: 1.6em 0 .6em; color: #111; }
.chapter-break { border: 0; border-top: 1px solid var(--line); margin: 48px auto; max-width: 220px; }

/* Chapter nav + paginated EPUB + TOC drawer */
#chapterNav {
  display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
  padding: 8px 20px; border-bottom: 1px solid var(--line); background: #fff;
  font-size: 13px;
}
#chapterNav.hidden { display: none; }
#chapterGroup, #viewToggle, #pageGroup { display: inline-flex; align-items: center; gap: 6px; }
#chapterGroup.hidden, #viewToggle.hidden, #pageGroup.hidden { display: none; }
#chapterLabel { font-weight: 650; max-width: 44vw; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
#pageLabel { font-size: 12px; color: var(--muted); min-width: 52px; text-align: center; }
.icon-btn.seg { border-radius: 0; }
.icon-btn.seg:first-child { border-radius: 8px 0 0 8px; }
.icon-btn.seg:last-child { border-radius: 0 8px 8px 0; margin-left: -7px; }
.icon-btn.seg.active { background: #1a1a1a; color: #fff; border-color: #1a1a1a; }

#epubPaged { flex: 1; overflow: hidden; background: #fff; }
#epubPaged.hidden { display: none; }
#pagedInner {
  height: 100%; color: #222;
  column-gap: 56px; padding: 34px 0; margin: 0 auto;
  transition: transform .18s ease;
}
#pagedInner img { max-width: 100%; height: auto; break-inside: avoid; border-radius: 6px; }
#pagedInner p, #pagedInner h1, #pagedInner h2, #pagedInner h3, #pagedInner figure, #pagedInner blockquote { break-inside: avoid; }
#pagedInner h1, #pagedInner h2, #pagedInner h3 { line-height: 1.25; color: #111; }

#tocDrawer {
  position: absolute; left: 0; top: 0; bottom: 0; width: min(320px, 84vw);
  background: #fff; border-right: 1px solid var(--line); z-index: 40;
  display: flex; flex-direction: column; box-shadow: 8px 0 30px rgba(0,0,0,.08);
}
#tocDrawer.hidden { display: none; }
.toc-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 14px; border-bottom: 1px solid var(--line);
  font-weight: 700; font-size: 14px;
}
#tocList { overflow-y: auto; padding: 6px; flex: 1; }
.toc-item {
  padding: 8px 10px; border-radius: 8px; cursor: pointer; font-size: 13.5px;
  display: flex; gap: 8px; align-items: baseline; line-height: 1.35;
}
.toc-item:hover { background: var(--soft); }
.toc-item.current { background: #1a1a1a; color: #fff; }
.toc-item.current .toc-time { color: #ccc; }
.toc-time { margin-left: auto; font-size: 11.5px; color: var(--muted); flex: none; }

/* PDF reader */
#pdfScroll { flex: 1; overflow-y: auto; background: #f4f4f4; }
#pdfScroll.hidden { display: none; }
#pdfPages { display: flex; flex-direction: column; align-items: center; gap: 16px; padding: 24px 16px 80px; }
.pdf-page {
  background: #fff; box-shadow: var(--shadow);
  position: relative; overflow: hidden;
}
.pdf-page canvas { display: block; width: 100%; height: auto; }
.pdf-page-num {
  position: absolute; right: 10px; bottom: 8px;
  font-size: 11px; color: #bbb; background: rgba(255,255,255,.85);
  padding: 1px 8px; border-radius: 99px; pointer-events: none;
}
#pdfPageLabel, #pdfZoomLabel { font-size: 12px; color: var(--muted); min-width: 52px; text-align: center; }
#readerControls .font-group.hidden { display: none; }

#audioWrap { flex: 1; overflow-y: auto; display: flex; align-items: flex-start; justify-content: center; padding: 48px 20px; }
#audioWrap.hidden { display: none; }
.audio-card { width: min(520px, 92vw); border: 1px solid var(--line); border-radius: 20px; padding: 36px 32px; text-align: center; box-shadow: var(--shadow); }
.audio-cover { width: 120px; height: 120px; border-radius: 24px; background: var(--soft); display: flex; align-items: center; justify-content: center; font-size: 52px; margin: 0 auto; overflow: hidden; }
.audio-cover img { width: 100%; height: 100%; object-fit: cover; display: block; }
.audio-title { font-size: 20px; font-weight: 750; margin-top: 16px; }
.audio-file { font-size: 12.5px; color: var(--muted); margin: 6px 0 18px; word-break: break-all; }
#audioEl { width: 100%; }
.audio-row { display: flex; gap: 10px; align-items: center; justify-content: center; margin-top: 16px; }
.speed-label { font-size: 13px; color: var(--muted); display: flex; gap: 6px; align-items: center; }
.speed-label select { border: 1px solid var(--line); border-radius: 8px; padding: 5px 8px; }
.audio-note { font-size: 12px; color: #b5b5b5; margin-top: 16px; }

/* Pointer-drag drop targets */
.folder-card.dragover { border-color: #1a1a1a; box-shadow: 0 0 0 2px #1a1a1a inset; }
#crumbHome.crumb-drop { background: #1a1a1a !important; color: #fff !important; border-radius: 99px; padding: 2px 12px; }
#flowChart.chart-drop { outline: 2px dashed #1a1a1a; outline-offset: -2px; border-radius: 14px; }
.book-card { touch-action: pan-x pan-y; }
.drag-ghost {
  position: fixed; z-index: 200; pointer-events: none;
  background: #1a1a1a; color: #fff; font-size: 13px; font-weight: 600;
  padding: 9px 16px; border-radius: 999px; box-shadow: 0 12px 30px rgba(0,0,0,.3);
  max-width: 280px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}

/* Clean reading (phone): hide every control, tap the page to get them back. */
#readerView.immersive #readerBar,
#readerView.immersive #chapterNav { display: none; }
#readerView.immersive #audioWrap { padding-top: 0; align-items: center; }
#readerView.immersive .audio-card { border: 0; box-shadow: none; padding: 16px; }
#readerView.immersive .audio-note { display: none; }
#readerView.immersive #epubScroll { padding-top: 22px; }
.immersive-hint {
  position: fixed; z-index: 40; left: 50%; bottom: 22px; transform: translateX(-50%);
  background: rgba(26,26,26,.86); color: #fff; font-size: 12.5px; padding: 8px 14px;
  border-radius: 999px; pointer-events: none; opacity: 0; transition: opacity .25s ease;
}
.immersive-hint.show { opacity: 1; }
/* Reader fullscreen — position must be restated: #readerView is position:relative
   in normal flow, and an author rule beats the UA's :fullscreen position:fixed,
   which left the top of the screen showing the library behind it. */
#readerView:fullscreen {
  position: fixed; inset: 0; top: 0; left: 0; right: 0; bottom: 0;
  width: 100%; height: 100%; background: #fff; z-index: 1;
}
#readerView:fullscreen #audioWrap { align-items: center; padding-top: 24px; }
#btnFullscreen.active { background: #1a1a1a; color: #fff; border-color: #1a1a1a; }

/* Reading flowchart (free nodes + connections) */
#orderSection.hidden { display: none; }
#orderHead { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
#orderHead .section-title { margin-bottom: 0; }
#orderActions { display: flex; gap: 8px; }
.btn.small { padding: 5px 12px; font-size: 12.5px; }
#orderHint { font-size: 12px; color: #b5b5b5; margin: 4px 0 2px; }
#flowChart {
  position: relative;
  /* Fixed viewport (not min-height): the world is `clientW/H x zoom` and
     scrolls inside this box in both axes, so no part of the chart can end up
     off-window where a node could never be dragged to. */
  height: clamp(320px, 48vh, 600px);
  border: 1px solid var(--line); border-radius: 14px; background: #fff;
  overflow: auto; margin: 8px 0 30px;
}
#flowInner { position: relative; }
#flowEdges { position: absolute; inset: 0; pointer-events: none; }
#flowEdges .edge { pointer-events: auto; cursor: pointer; }
#flowEdges .edge-hit { stroke: rgba(0,0,0,0); stroke-width: 14; fill: none; pointer-events: stroke; }
#flowEdges .edge-line { stroke: #b5b5b5; stroke-width: 2.5; fill: none; pointer-events: none; }
#flowEdges .edge:hover .edge-line { stroke: #1a1a1a; }
.flow-node {
  position: absolute; width: 150px;
  border: 1px solid var(--line); border-radius: 12px; background: #fff;
  padding: 12px 10px 10px; text-align: center; cursor: grab; user-select: none;
  box-shadow: var(--shadow);
}
.flow-node:active { cursor: grabbing; }
.flow-node.link-source { border-color: #1a1a1a; border-style: dashed; box-shadow: 0 0 0 2px #1a1a1a inset; }
.flow-node.selected { outline: 2px dashed #2b7fff; outline-offset: 3px; }
.flow-node.section-hi { box-shadow: 0 0 0 3px currentColor, var(--shadow); }
.node-label { font-size: 13px; font-weight: 650; line-height: 1.35; word-break: break-word; }
.node-book {
  display: inline-block; margin-top: 7px; font-size: 12px; font-weight: 600; cursor: pointer;
  border: 1px solid var(--line); border-radius: 8px; padding: 2px 10px; background: var(--soft);
}
.node-book:hover { border-color: #1a1a1a; }
.flow-remove {
  position: absolute; top: -9px; right: -9px; width: 22px; height: 22px; border-radius: 50%;
  background: #fff; border: 1px solid var(--line); color: #999; font-size: 12px; line-height: 1;
  display: none; align-items: center; justify-content: center; cursor: pointer;
}
.flow-node:hover .flow-remove { display: flex; }
.flow-remove:hover { color: #c0392b; border-color: #c0392b; }
.flow-empty {
  position: absolute; inset: 0; display: flex; flex-direction: column;
  align-items: center; justify-content: center; gap: 4px;
  color: var(--muted); font-size: 13.5px; text-align: center; padding: 20px;
  pointer-events: none;
}
.flow-empty .btn { margin-top: 10px; pointer-events: auto; }

/* Chart zoom + sections */
#chartZoomLabel { font-size: 12px; color: var(--muted); min-width: 44px; text-align: center; }
#sectionBar { display: flex; gap: 8px; flex-wrap: wrap; margin: 2px 0 0; }
#sectionBar.hidden { display: none; }
.section-chip {
  display: inline-flex; align-items: center; gap: 7px;
  border: 1px solid var(--line); border-radius: 999px; background: #fff;
  padding: 4px 8px 4px 10px; font-size: 12.5px; font-weight: 600; cursor: pointer;
  user-select: none;
}
.section-chip:hover { border-color: #999; }
.section-dot { width: 11px; height: 11px; border-radius: 50%; flex: none; }
.section-count { color: var(--muted); font-weight: 400; font-size: 11.5px; }
.section-x {
  border: none; background: none; color: #bbb; cursor: pointer;
  font-size: 13px; line-height: 1; padding: 0 2px;
}
.section-x:hover { color: #c0392b; }
.lasso-rect {
  position: absolute; border: 1.5px dashed #2b7fff; background: rgba(43,127,255,.08);
  pointer-events: none; z-index: 30;
}

/* Context menu */
#contextMenu {
  position: fixed; z-index: 100; min-width: 210px;
  background: #fff; border: 1px solid var(--line); border-radius: 12px;
  box-shadow: 0 12px 40px rgba(0,0,0,.14);
  padding: 6px; font-size: 13.5px;
}
#contextMenu.hidden { display: none; }
#contextMenu { max-height: 62vh; overflow-y: auto; }
.ctx-item { padding: 9px 12px; border-radius: 8px; cursor: pointer; display: flex; gap: 8px; align-items: center; }
.ctx-item:hover { background: var(--soft); }
.ctx-item.danger { color: #c0392b; }
.ctx-sep { height: 1px; background: var(--line); margin: 5px 4px; }
.ctx-label { font-size: 11px; text-transform: uppercase; letter-spacing: .07em; color: var(--muted); padding: 7px 12px 3px; }

/* Modal */
#modalOverlay { position: fixed; inset: 0; background: rgba(0,0,0,.18); z-index: 90; display: flex; align-items: center; justify-content: center; }
#modalOverlay.hidden { display: none; }
#modal { background: #fff; border-radius: 16px; padding: 22px; width: min(380px, 90vw); box-shadow: 0 24px 70px rgba(0,0,0,.2); }
#modal h3 { margin: 0 0 12px; font-size: 16px; }
#modalInput { width: 100%; padding: 10px 12px; border: 1px solid var(--line); border-radius: 10px; font-size: 14px; outline: none; }
#modalInput:focus { border-color: #999; }
.modal-actions { display: flex; justify-content: flex-end; gap: 8px; margin-top: 16px; }
#colorRow { display: flex; gap: 10px; margin-top: 14px; align-items: center; flex-wrap: wrap; }
#colorRow.hidden { display: none; }
.swatch { width: 30px; height: 30px; border-radius: 50%; cursor: pointer; border: 2px solid transparent; }
.swatch.selected { border-color: #1a1a1a; }

#toast {
  position: fixed; bottom: 26px; left: 50%; transform: translateX(-50%);
  background: #1a1a1a; color: #fff; font-size: 13.5px;
  padding: 11px 20px; border-radius: 999px; z-index: 120;
  box-shadow: 0 10px 30px rgba(0,0,0,.25);
}
#toast.hidden { display: none; }

@media (max-width: 720px) {
  #libHint { display: none; }
  #searchInput { width: 38vw; }
  #readerControls .font-group select { max-width: 90px; }
}