/* ── Theme: VLOOK Thinking ──────────────────────────────────── */

:root {
  /* Wire app vars → VLOOK Thinking variables */
  --v-bg:       var(--db, #fff);
  --v-nav-bg:   var(--db, #f8f8f8);
  --v-tt:       var(--df, #1c1e1f);
  --v-tt-2:     var(--df-a, #7d868a);
  --v-tt-3:     var(--df-a, #999);
  --v-bd:       var(--df02, rgba(28,30,31,0.2));
  --v-ac:       var(--ac-t1, #298bcc);
  --v-ac-bg:    var(--ac-t1-a, #ddedf8);
  --v-hover-bg: var(--df01, rgba(28,30,31,0.1));
  --v-f-size:   16px;
}

/* ── Layout ─────────────────────────────────────────────────── */

*, *::before, *::after { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  overflow: hidden;  /* body does not scroll — #main handles scrolling */
}

body {
  display: flex;
  flex-direction: row;
  background: var(--v-bg, #fff);
  color: var(--v-tt, #1c1e1f);
  font-size: var(--v-f-size, 16px);
  font-family: var(--v-fm-text, "霞鹜文楷", Georgia, serif);
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--v-fm-h, "阿里妈妈东方大楷", "DongFangDaKai", "霞鹜文楷", Georgia, serif);
}

strong, b {
  font-weight: 700;
}

code, pre {
  font-family: var(--v-fm-code, "Go Mono", GoMono, Consolas, monospace);
}

/* Sidebar */
#sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: 260px;
  height: 100vh;
  overflow-y: auto;
  background: var(--v-nav-bg, #f8f8f8);
  border-right: 1px solid var(--v-bd, #e0e0e0);
  padding: 16px 0 32px;
  z-index: 100;
  transition: transform 0.25s ease;
}

#sidebar.hidden {
  transform: translateX(-260px);
}

/* Dim overlay for mobile */
#overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.35);
  z-index: 99;
}
#overlay.visible { display: block; }

.nav-section-title {
  font-size: 0.7em;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--v-tt-3, #888);
  padding: 8px 20px 4px;
}

.nav-divider {
  height: 1px;
  background: var(--v-bd, #e0e0e0);
  margin: 12px 16px;
}

/* Chapter navigation list */
#doc-nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

#doc-nav-list li a {
  display: block;
  padding: 6px 20px;
  font-size: 0.85em;
  color: var(--v-tt-2, #555);
  text-decoration: none;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  border-left: 3px solid transparent;
  transition: background 0.15s, border-color 0.15s;
}

#doc-nav-list li a:hover {
  background: var(--v-hover-bg, rgba(28,30,31,0.1));
  color: var(--v-ac, #298bcc);
}

#doc-nav-list li a.current {
  border-left-color: var(--v-ac, #298bcc);
  color: var(--v-ac, #298bcc);
  font-weight: 600;
  background: var(--v-ac-bg, #ddedf8);
}

/* Inline TOC sub-list — rendered inside the current chapter's nav-chapter li */
ul.chapter-toc {
  list-style: none;
  margin: 4px 0 4px;
  padding: 0;
  border-left: 2px solid var(--v-bd, #e0e0e0);
  margin-left: 20px;
  display: none;                        /* whole TOC hidden until chapter clicked */
}
.nav-chapter-current.open ul.chapter-toc          { display: block; }

ul.chapter-toc ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

/* The top-level sections list is always visible once the chapter is open */
.nav-chapter-current.open ul.chapter-toc > li > ul { display: block; }

/* Deeper nested lists (subsections, sub-subsections) start hidden */
ul.chapter-toc > li > ul > li > ul               { display: none; }
ul.chapter-toc > li > ul > li.open > ul          { display: block; }
ul.chapter-toc > li > ul > li > ul > li > ul     { display: none; }
ul.chapter-toc > li > ul > li > ul > li.open > ul { display: block; }

ul.chapter-toc li a {
  display: block;
  padding: 3px 8px;
  font-size: 0.8em;
  color: var(--v-tt-2, #666);
  text-decoration: none;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  transition: color 0.15s, background 0.15s;
  border-radius: 3px;
}

/* Hide the duplicate chapter title (top-level anchor) — must come after li a rule */
ul.chapter-toc > li > a {
  display: none !important;
}

/* Expand/collapse arrow on chapter nav entry */
.nav-chapter-current > a::before {
  content: "▶ ";
  font-size: 0.6em;
  opacity: 0.5;
}
.nav-chapter-current.open > a::before {
  content: "▼ ";
}


ul.chapter-toc li a:hover {
  color: var(--v-ac, #298bcc);
  background: var(--v-hover-bg, rgba(28,30,31,0.06));
}

ul.chapter-toc li a.toc-active {
  color: var(--v-ac, #298bcc);
  font-weight: 600;
}

/* Section level (1.1): base indent */
ul.chapter-toc > li > ul > li > a {
  padding-left: 10px !important;
}

/* Subsection level (1.1.1): extra indent */
ul.chapter-toc > li > ul > li > ul > li > a {
  padding-left: 28px !important;
  font-size: 0.77em;
  color: var(--v-tt-3, #999);
}

/* Main content area */
#main {
  margin-left: 260px;
  flex: 1;
  min-width: 0;
  height: 100%;
  overflow-y: auto;
  overflow-x: hidden;
  display: flex;
  flex-direction: column;
}

#topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 0 24px;
  height: 48px;
  background: var(--v-bg, #fff);
  border-bottom: 1px solid var(--v-bd, #e0e0e0);
}

#sidebar-toggle {
  background: none;
  border: none;
  font-size: 1.2em;
  cursor: pointer;
  color: var(--v-tt-2, #555);
  padding: 4px 8px;
  border-radius: 4px;
  display: none;   /* shown only on narrow screens */
}

#topbar-title {
  font-size: 0.9em;
  font-weight: 600;
  color: var(--v-tt-2, #555);
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

#pdf-btn {
  background: none;
  border: none;
  font-size: 1.1em;
  cursor: pointer;
  color: var(--v-tt-2, #555);
  padding: 4px 8px;
  border-radius: 4px;
}
#pdf-btn:hover { background: var(--v-hover-bg, rgba(0,0,0,0.05)); }

#content {
  max-width: 860px;
  width: 100%;
  margin: 0 auto;
  padding: 32px 40px 80px;
}

/* ── Math overflow (KaTeX wide equations) ───────────────────── */

.math.display,
.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0.4em 0;
}

/* Prevent inline math from causing line overflow */
.math.inline {
  word-break: keep-all;
}

/* ── Callout blocks ─────────────────────────────────────────── */

.callout {
  border-radius: 6px;
  margin: 1.2em 0;
  overflow: hidden;
  border: 1px solid transparent;
}

.callout-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  font-size: 0.95em;
  font-weight: 700;
  font-family: "Microsoft YaHei", "微软雅黑", "PingFang SC", "Noto Sans SC", "Source Han Sans CN", sans-serif;
  letter-spacing: 0.06em;
}

.callout-icon::before {
  font-style: normal;
}

.callout-body {
  padding: 10px 14px 14px;
  font-size: 0.95em;
}

.callout-body > *:first-child { margin-top: 0; }
.callout-body > *:last-child  { margin-bottom: 0; }

.callout-body > p:first-of-type {
  text-indent: 2em;
}

/* Per-type colors */
.callout-note    { background: #eff6ff; border-color: #bfdbfe; }
.callout-note    .callout-header { background: #dbeafe; color: #1d4ed8; }
.callout-note    .callout-icon::before { content: "📝 "; }

.callout-tip     { background: #f0fdf4; border-color: #bbf7d0; }
.callout-tip     .callout-header { background: #dcfce7; color: #15803d; }
.callout-tip     .callout-icon::before { content: "💡 "; }

.callout-important { background: #faf5ff; border-color: #e9d5ff; }
.callout-important .callout-header { background: #f3e8ff; color: #7e22ce; }
.callout-important .callout-icon::before { content: "⭐ "; }

.callout-warning { background: #fffbeb; border-color: #fde68a; }
.callout-warning .callout-header { background: #fef3c7; color: #b45309; }
.callout-warning .callout-icon::before { content: "⚠️ "; }

.callout-caution { background: #fff1f2; border-color: #fecdd3; }
.callout-caution .callout-header { background: #ffe4e6; color: #be123c; }
.callout-caution .callout-icon::before { content: "🔥 "; }

.callout-extension { background: #f0f9ff; border-color: #bae6fd; }
.callout-extension .callout-header { background: #e0f2fe; color: #0369a1; }
.callout-extension .callout-icon::before { content: "🔭 "; }


/* ── Highlighted text ==text== ──────────────────────────────── */

mark {
  background: #fef08a;
  color: inherit;
  padding: 0 2px;
  border-radius: 2px;
}

/* ── Semantic inline spans ──────────────────────────────────── */

/* [text]{.hl} — soft yellow highlight */
.hl {
  background: #fef9c3;
  color: inherit;
  padding: 0 3px;
  border-radius: 2px;
}

/* [text]{.key} — accent-colored key term */
.key {
  color: var(--v-ac, #298bcc);
  font-weight: 600;
}

/* ── Auto chapter numbering ─────────────────────────────────── */

body.chp-autonum {
  counter-reset: h2cnt;
}
body.chp-autonum h2 {
  counter-reset: h3cnt;
  counter-increment: h2cnt;
}
body.chp-autonum h2::before {
  content: counter(h2-cnt) ". ";
}
body.chp-autonum h3 {
  counter-reset: h4cnt;
  counter-increment: h3cnt;
}
body.chp-autonum h3::before {
  content: counter(h2cnt) "." counter(h3cnt) " ";
}
body.chp-autonum h4 {
  counter-increment: h4cnt;
}
body.chp-autonum h4::before {
  content: counter(h2cnt) "." counter(h3cnt) "." counter(h4cnt) " ";
}

/* ── Video panel ─────────────────────────────────────────────── */

#video-panel {
  display: none;
  max-width: 860px;
  width: calc(100% - 80px);
  margin: 16px auto;
  border-radius: 6px;
  background: #000;
  scroll-margin-top: 60px;
}

#video-frame {
  display: block;
  width: 100%;
  border: none;
}

#video-panel {
  position: relative;  /* anchor for the close button */
}

#video-close-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  z-index: 10;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  border: none;
  background: rgba(0,0,0,0.55);
  color: #fff;
  font-size: 1.1em;
  line-height: 1;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s;
}
#video-close-btn:hover { background: rgba(0,0,0,0.85); }

#video-close-bottom {
  display: block;
  width: 100%;
  padding: 8px;
  background: rgba(0,0,0,0.7);
  color: #ccc;
  border: none;
  font-size: 0.82em;
  cursor: pointer;
  text-align: center;
  transition: background 0.15s, color 0.15s;
}
#video-close-bottom:hover {
  background: rgba(0,0,0,0.9);
  color: #fff;
}

.video-inline-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  margin: 6px 0 14px;
  padding: 4px 12px;
  background: none;
  border: 1px solid var(--v-ac, #298bcc);
  border-radius: 4px;
  color: var(--v-ac, #298bcc);
  font-size: 0.82em;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}
.video-inline-btn:hover {
  background: var(--v-ac, #298bcc);
  color: #fff;
}

/* ── Print / PDF mode ───────────────────────────────────────── */

@media print {
  #sidebar, #topbar, #overlay, #video-panel { display: none !important; }
  #main { margin-left: 0 !important; }
  #content { max-width: 100% !important; padding: 0 !important; }

  .callout { break-inside: avoid; }

  /* Ensure math doesn't get clipped in PDF */
  .math.display, .katex-display {
    overflow: visible !important;
  }
}

/* ── Responsive: narrow screens ────────────────────────────── */

@media (max-width: 900px) {
  #sidebar {
    transform: translateX(-260px);
  }
  #sidebar.open {
    transform: translateX(0);
  }
  #main {
    margin-left: 0;
  }
  #sidebar-toggle {
    display: block;
  }
  #content {
    padding: 24px 20px 60px;
  }
}

/* ── Exercise blocks ─────────────────────────────────────────── */

.exercise-block {
  border: 1px solid #bfdbfe;
  border-radius: 6px;
  margin: 1.5rem 0;
  background: #eff6ff;
  overflow: hidden;
}

/* Colored banner — matches [!note] callout header */
.ex-banner {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  padding: 7px 14px;
  background: #dbeafe;
  color: #1d4ed8;
  font-family: "Microsoft YaHei", "微软雅黑", "PingFang SC", "Noto Sans SC", "Source Han Sans CN", sans-serif;
  font-weight: 700;
  font-size: 1em;
  letter-spacing: 0.05em;
}

.ex-dot {
  font-size: 0.65em;
  line-height: 1;
  flex-shrink: 0;
}

.ex-label {
  font-weight: 700;
  font-size: 1em;
  color: inherit;
  flex: 1;
}

/* Body area below banner */
.ex-body {
  padding: 0.85rem 1.2rem 1rem;
}

/* Problem content box with deep-blue left border */
.ex-problem-box {
  background: #fff;
  border: 1px solid #93c5fd;
  border-left: 3px solid #1d4ed8;
  border-radius: 4px;
  padding: 0.55rem 0.9rem 0.55rem 0.85rem;
  margin-bottom: 0.85rem;
  line-height: 1.7;
}

.ex-problem-box > *:first-child { margin-top: 0; }
.ex-problem-box > *:last-child  { margin-bottom: 0; }

/* "题目：" as plain bold inline text before first paragraph */
.ex-problem-box > p:first-child::before {
  content: "题目：";
  font-weight: 700;
  font-family: "Microsoft YaHei", "微软雅黑", "PingFang SC", "Noto Sans SC", sans-serif;
  color: #1d4ed8;
  margin-right: 0.1em;
}

.ex-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.2rem;
}

.ex-tag {
  font-size: 0.6em;
  padding: 1px 5px;
  border-radius: 8px;
  background: var(--v-hover-bg, rgba(28,30,31,0.07));
  color: var(--v-tt-2, #7d868a);
  letter-spacing: 0.02em;
}


.ex-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem;
}

/* Solution rows */
.ex-sol-row {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0;
  margin-bottom: 0.3rem;
}

.ex-sol-label {
  font-size: 0.88em;
  font-weight: 600;
  color: var(--v-tt-2, #7d868a);
  background: var(--v-hover-bg, rgba(28,30,31,0.06));
  border: 1px solid var(--v-bd, #e0e0e0);
  border-radius: 4px;
  padding: 2px 10px;
  user-select: none;
  letter-spacing: 0.03em;
}

.ex-sol-btns {
  display: inline-flex;
  gap: 0;
}

/* Sticker-tab action buttons: 提示 / 答案 */
.ex-action-btn {
  padding: 1px 8px;
  border: none;
  border-radius: 3px;
  font-size: 0.65em;
  font-weight: 600;
  cursor: pointer;
  transition: filter 0.15s, opacity 0.15s;
  line-height: 1.6;
}

.ex-hint-btn {
  background: #fde68a;
  color: #78350f;
  border-radius: 3px 0 0 3px;
}
.ex-hint-btn:hover, .ex-hint-btn.active { filter: brightness(0.9); }

.ex-ans-btn {
  background: #a7f3d0;
  color: #064e3b;
  border-radius: 0 3px 3px 0;
  border-left: 1px solid rgba(0,0,0,0.08);
}
.ex-ans-btn:hover, .ex-ans-btn.active { filter: brightness(0.9); }


/* Video link */
.ex-video-btn {
  padding: 3px 10px;
  border: 1px solid var(--v-bd, #e0e0e0);
  border-radius: 12px;
  color: var(--v-tt-2, #7d868a);
  font-size: 0.8em;
  text-decoration: none;
  transition: border-color 0.15s;
}

.ex-video-btn:hover {
  border-color: var(--v-ac, #298bcc);
  color: var(--v-ac, #298bcc);
}

/* Fixed content frame */
.ex-frame {
  margin-top: 0.75rem;
  border: 1px solid var(--v-bd, #e0e0e0);
  border-radius: 4px;
  background: var(--v-nav-bg, #f8f8f8);
  max-height: 280px;
  overflow-y: auto;
}

.ex-panel {
  padding: 0.75rem 1rem;
  line-height: 1.75;
}

/* Hint panel: muted gray, mysterious */
.ex-hint-panel {
  background: #e8e8e8;
  color: #3a3a3a;
  border-left: 3px solid #d4a72c;
  font-style: italic;
}

/* Answer panel: clean white, authoritative */
.ex-ans-panel {
  background: #ffffff;
  color: #111111;
  border-left: 3px solid #059669;
}

/* "解答：" inline before the first paragraph of each answer panel */
.ex-ans-panel > p:first-child::before {
  content: "解答：";
  font-weight: 700;
  font-family: "Microsoft YaHei", "微软雅黑", "PingFang SC", "Noto Sans SC", sans-serif;
  color: #065f46;
  margin-right: 0.1em;
}

.ex-panel p { margin: 0.4em 0; }
.ex-panel p:first-child { margin-top: 0; }
.ex-panel p:last-child { margin-bottom: 0; }