/* 🎨 MCA Sem 3 Study World — Minimalist Swiss / Linear Focus Design System */

:root {
  /* Minimal High-Focus Palette (Light) */
  --bg-app: #FAFAFA;
  --bg-sidebar: #FFFFFF;
  --bg-sidebar-hover: #F4F4F5;
  --bg-card: #FFFFFF;
  --bg-card-hover: #FAFAFA;
  --bg-card-active: #EFF6FF;
  --border-card-active: #3B82F6;
  --border-subtle: #E5E7EB;
  --border-light: #F3F4F6;
  
  /* Primary Royal Cobalt */
  --accent-primary: #2563EB;
  --accent-primary-hover: #1D4ED8;
  --accent-soft: #EFF6FF;
  --accent-tag-bg: #DBEAFE;
  --accent-tag-text: #1E40AF;

  /* Tag Color Variants */
  --tag-indigo-bg: #EEF2FF;
  --tag-indigo-text: #3730A3;
  --tag-amber-bg: #FEF3C7;
  --tag-amber-text: #92400E;
  --tag-blue-bg: #DBEAFE;
  --tag-blue-text: #1E40AF;
  --tag-emerald-bg: #ECFDF5;
  --tag-emerald-text: #065F46;
  --tag-rose-bg: #FFF1F2;
  --tag-rose-text: #9F1239;
  --tag-purple-bg: #F5F3FF;
  --tag-purple-text: #6B21A8;

  /* Text & Hierarchy */
  --text-main: #111827;
  --text-muted: #6B7280;
  --text-subtle: #9CA3AF;
  --text-inverse: #FFFFFF;

  /* Prose & Code */
  --code-bg: #0F172A;
  --code-text: #F8FAFC;
  --inline-code-bg: #F3F4F6;
  --inline-code-text: #2563EB;
  --blockquote-border: #3B82F6;
  --blockquote-bg: #F8FAFC;
  
  /* Shadows & Radii */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.06), 0 2px 4px -2px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 12px 24px -4px rgba(0, 0, 0, 0.08);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-pill: 9999px;

  /* Distinct Editorial Typography */
  --font-heading: 'Space Grotesk', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-body: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-code: 'Fira Code', monospace;

  /* Layout Widths */
  --sidebar-width: 270px;
  --topic-list-width: 340px;
}

/* Eye-Comfort Dark Theme */
[data-theme="dark"] {
  --bg-app: #0A0E17;
  --bg-sidebar: #101622;
  --bg-sidebar-hover: #1A2234;
  --bg-card: #101622;
  --bg-card-hover: #182030;
  --bg-card-active: #172554;
  --border-card-active: #60A5FA;
  --border-subtle: #1F293D;
  --border-light: #161F2E;
  
  --accent-primary: #3B82F6;
  --accent-primary-hover: #60A5FA;
  --accent-soft: #172554;
  --accent-tag-bg: #1E3A8A;
  --accent-tag-text: #BFDBFE;

  --tag-indigo-bg: #1E1B4B;
  --tag-indigo-text: #C7D2FE;
  --tag-amber-bg: #451A03;
  --tag-amber-text: #FCD34D;
  --tag-blue-bg: #172554;
  --tag-blue-text: #93C5FD;
  --tag-emerald-bg: #064E3B;
  --tag-emerald-text: #6EE7B7;
  --tag-rose-bg: #4C0519;
  --tag-rose-text: #FDA4AF;
  --tag-purple-bg: #3B0764;
  --tag-purple-text: #D8B4FE;

  --text-main: #F9FAFB;
  --text-muted: #9CA3AF;
  --text-subtle: #6B7280;

  --code-bg: #05080E;
  --code-text: #F8FAFC;
  --inline-code-bg: #1A2234;
  --inline-code-text: #93C5FD;
  --blockquote-border: #3B82F6;
  --blockquote-bg: #101622;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 12px 24px -4px rgba(0, 0, 0, 0.5);
}

/* Reset & Smooth Transitions */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

html, body {
  height: 100%;
  width: 100%;
  overflow: hidden;
  background-color: var(--bg-app);
  color: var(--text-main);
  font-family: var(--font-body);
  font-size: 14.5px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.app-container {
  display: flex;
  height: 100vh;
  width: 100vw;
  overflow: hidden;
  position: relative;
}

/* ============================================================
   COLUMN 1: SIDEBAR
============================================================ */
.sidebar {
  width: var(--sidebar-width);
  height: 100%;
  background-color: var(--bg-sidebar);
  border-right: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  user-select: none;
  z-index: 50;
}

.sidebar-header {
  padding: 16px 18px 12px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text-main);
}

.brand-icon-svg {
  width: 32px;
  height: 32px;
  flex-shrink: 0;
}

.brand-title {
  font-family: var(--font-heading);
  font-size: 1.12rem;
  font-weight: 700;
  letter-spacing: -0.3px;
  line-height: 1.2;
}

.brand-title span {
  color: var(--accent-primary);
}

.header-action-btn {
  background: var(--bg-sidebar-hover);
  border: 1px solid var(--border-subtle);
  color: var(--text-muted);
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.header-action-btn:hover {
  color: var(--text-main);
  border-color: var(--accent-primary);
}

/* Author Signature Card */
.author-card {
  margin: 2px 14px 12px 14px;
  padding: 8px 10px;
  background: var(--bg-sidebar-hover);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  gap: 9px;
}

.author-avatar {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent-primary), #1D4ED8);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 12px;
  flex-shrink: 0;
}

.author-info {
  flex: 1;
  min-width: 0;
}

.author-name {
  font-weight: 700;
  font-size: 0.82rem;
  color: var(--text-main);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.author-tag {
  font-size: 0.7rem;
  color: var(--text-muted);
}

/* Sidebar Scroll Area */
.sidebar-content {
  flex: 1;
  overflow-y: auto;
  padding: 2px 10px 18px 10px;
}

.sidebar-content::-webkit-scrollbar {
  width: 3px;
}
.sidebar-content::-webkit-scrollbar-thumb {
  background-color: var(--border-subtle);
  border-radius: 3px;
}

.sidebar-section {
  margin-bottom: 16px;
}

.section-label {
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--text-subtle);
  padding: 4px 8px;
  margin-bottom: 2px;
}

.nav-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.86rem;
  cursor: pointer;
  margin-bottom: 2px;
}

.nav-item:hover {
  background-color: var(--bg-sidebar-hover);
  color: var(--text-main);
}

.nav-item.active {
  background-color: var(--accent-soft);
  color: var(--accent-primary);
  font-weight: 700;
}

.nav-item-left {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
}

.nav-item-left span.icon {
  font-size: 15px;
  width: 18px;
  text-align: center;
}

.nav-title {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav-badge {
  font-size: 0.68rem;
  font-weight: 700;
  padding: 2px 6px;
  border-radius: var(--radius-pill);
  background-color: var(--bg-sidebar-hover);
  color: var(--text-muted);
}

.nav-item.active .nav-badge {
  background-color: var(--accent-primary);
  color: white;
}

.sidebar-footer {
  padding: 10px 14px;
  border-top: 1px solid var(--border-subtle);
  font-size: 0.7rem;
  color: var(--text-subtle);
  line-height: 1.3;
}

/* ============================================================
   COLUMN 2: TOPIC LIST
============================================================ */
.topic-list-panel {
  width: var(--topic-list-width);
  height: 100%;
  background-color: var(--bg-app);
  border-right: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  z-index: 30;
}

.topic-list-header {
  padding: 14px 14px 10px 14px;
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.search-container {
  position: relative;
  display: flex;
  align-items: center;
}

.search-input {
  width: 100%;
  padding: 8px 32px 8px 32px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: 0.85rem;
  color: var(--text-main);
  outline: none;
  box-shadow: var(--shadow-sm);
}

.search-input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.15);
}

.search-icon-left {
  position: absolute;
  left: 10px;
  color: var(--text-subtle);
  font-size: 13px;
  pointer-events: none;
}

.search-shortcut-hint {
  position: absolute;
  right: 8px;
  background: var(--bg-sidebar-hover);
  border: 1px solid var(--border-subtle);
  padding: 1px 5px;
  border-radius: 3px;
  font-size: 0.65rem;
  font-family: var(--font-code);
  color: var(--text-subtle);
  pointer-events: none;
}

.topic-filter-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.active-category-title {
  font-family: var(--font-heading);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 6px;
}

/* Filter Tabs */
.filter-tabs-row {
  display: flex;
  gap: 5px;
  overflow-x: auto;
  padding-bottom: 2px;
}

.filter-tabs-row::-webkit-scrollbar {
  display: none;
}

.filter-chip {
  padding: 4px 10px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-pill);
  font-size: 0.74rem;
  font-weight: 600;
  color: var(--text-muted);
  white-space: nowrap;
  cursor: pointer;
}

.filter-chip:hover {
  border-color: var(--accent-primary);
  color: var(--text-main);
}

.filter-chip.active {
  background-color: var(--accent-primary);
  border-color: var(--accent-primary);
  color: white;
}

/* Topic Cards */
.topic-cards-container {
  flex: 1;
  overflow-y: auto;
  padding: 10px 12px 20px 12px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.topic-cards-container::-webkit-scrollbar {
  width: 4px;
}
.topic-cards-container::-webkit-scrollbar-thumb {
  background-color: var(--border-subtle);
  border-radius: 4px;
}

.note-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 11px 12px;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  gap: 5px;
  box-shadow: var(--shadow-sm);
}

.note-card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.note-card.active {
  background-color: var(--bg-card-active);
  border-color: var(--accent-primary);
}

.card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 6px;
}

.card-title {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.3;
}

.note-card.active .card-title {
  color: var(--accent-primary);
}

.card-preview-text {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 2px;
}

.card-meta {
  font-size: 0.7rem;
  color: var(--text-subtle);
}

.card-tags {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-wrap: wrap;
}

.tag-pill {
  font-size: 0.66rem;
  font-weight: 700;
  padding: 1px 6px;
  border-radius: var(--radius-pill);
  background-color: var(--accent-tag-bg);
  color: var(--accent-tag-text);
}

.tag-pill.indigo { background: var(--tag-indigo-bg); color: var(--tag-indigo-text); }
.tag-pill.amber { background: var(--tag-amber-bg); color: var(--tag-amber-text); }
.tag-pill.blue { background: var(--tag-blue-bg); color: var(--tag-blue-text); }
.tag-pill.emerald { background: var(--tag-emerald-bg); color: var(--tag-emerald-text); }
.tag-pill.rose { background: var(--tag-rose-bg); color: var(--tag-rose-text); }
.tag-pill.purple { background: var(--tag-purple-bg); color: var(--tag-purple-text); }

/* ============================================================
   COLUMN 3: CANVAS & READING AREA
============================================================ */
.note-canvas-panel {
  flex: 1;
  height: 100%;
  background-color: var(--bg-app);
  display: flex;
  flex-direction: column;
  min-width: 0;
  overflow: hidden;
  position: relative;
}

.canvas-toolbar {
  height: 52px;
  padding: 0 24px;
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: var(--bg-card);
  flex-shrink: 0;
  z-index: 20;
}

.toolbar-left {
  display: flex;
  align-items: center;
  gap: 10px;
}

.mobile-menu-btn {
  display: none;
  background: var(--bg-app);
  border: 1px solid var(--border-subtle);
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-main);
}

.canvas-breadcrumbs {
  display: flex;
  align-items: center;
  gap: 5px;
  font-size: 0.82rem;
  color: var(--text-muted);
}

.breadcrumb-folder {
  font-weight: 700;
  color: var(--accent-primary);
}

.toolbar-right {
  display: flex;
  align-items: center;
  gap: 6px;
}

.tool-btn {
  background: var(--bg-app);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 5px 10px;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 5px;
}

.tool-btn:hover {
  color: var(--text-main);
  border-color: var(--accent-primary);
}

.tool-btn.primary {
  background: var(--accent-primary);
  border-color: var(--accent-primary);
  color: white;
}

.tool-btn.primary:hover {
  background: var(--accent-primary-hover);
}

.tool-btn.active-focus {
  background: var(--accent-primary) !important;
  color: white !important;
  border-color: var(--accent-primary) !important;
}

/* Reading Canvas Layout */
.canvas-body-wrapper {
  flex: 1;
  display: flex;
  overflow: hidden;
  position: relative;
}

.markdown-scroll-container {
  flex: 1;
  overflow-y: auto;
  padding: 28px 36px 50px 36px;
  scroll-behavior: smooth;
}

.markdown-scroll-container::-webkit-scrollbar {
  width: 5px;
}
.markdown-scroll-container::-webkit-scrollbar-thumb {
  background-color: var(--border-subtle);
  border-radius: 4px;
}

.markdown-prose-container {
  max-width: 820px;
  margin: 0 auto;
}

/* Study Mode Tabs */
.study-mode-tabs {
  display: flex;
  gap: 6px;
  border-bottom: 1px solid var(--border-subtle);
  margin-bottom: 20px;
  overflow-x: auto;
}

.study-mode-tabs::-webkit-scrollbar {
  display: none;
}

.study-tab-btn {
  background: transparent;
  border: none;
  padding: 8px 14px;
  font-family: var(--font-heading);
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-muted);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  white-space: nowrap;
  display: flex;
  align-items: center;
  gap: 5px;
}

.study-tab-btn:hover {
  color: var(--text-main);
}

.study-tab-btn.active {
  color: var(--accent-primary);
  border-bottom-color: var(--accent-primary);
}

/* Markdown Prose */
.markdown-prose {
  color: var(--text-main);
  font-size: 0.98rem;
  line-height: 1.7;
}

.markdown-prose h1 {
  font-family: var(--font-heading);
  font-size: 1.85rem;
  font-weight: 800;
  letter-spacing: -0.4px;
  color: var(--text-main);
  margin-bottom: 12px;
  line-height: 1.25;
}

.markdown-prose h2 {
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.2px;
  color: var(--text-main);
  margin-top: 28px;
  margin-bottom: 12px;
  padding-bottom: 5px;
  border-bottom: 1px solid var(--border-subtle);
}

.markdown-prose h3 {
  font-family: var(--font-heading);
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--accent-primary);
  margin-top: 20px;
  margin-bottom: 8px;
  padding: 5px 8px;
  border-radius: var(--radius-sm);
  background: var(--bg-card-hover);
}

.markdown-prose h3.flash-focus {
  background-color: var(--accent-soft);
  border-left: 3px solid var(--accent-primary);
  animation: flashHighlight 1.5s ease-out;
}

@keyframes flashHighlight {
  0% { background-color: #FEF08A; }
  100% { background-color: var(--accent-soft); }
}

.markdown-prose p {
  margin-bottom: 12px;
}

.markdown-prose ul, .markdown-prose ol {
  margin-bottom: 14px;
  padding-left: 22px;
}

.markdown-prose li {
  margin-bottom: 5px;
}

.markdown-prose blockquote {
  background-color: var(--blockquote-bg);
  border-left: 3px solid var(--blockquote-border);
  padding: 10px 14px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 16px 0;
  font-size: 0.92rem;
}

/* Tables */
.markdown-prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 18px 0;
  background-color: var(--bg-card);
  border-radius: var(--radius-sm);
  overflow: hidden;
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-sm);
}

.markdown-prose th, .markdown-prose td {
  padding: 9px 12px;
  text-align: left;
  border-bottom: 1px solid var(--border-subtle);
  font-size: 0.88rem;
}

.markdown-prose th {
  background-color: var(--bg-sidebar-hover);
  font-family: var(--font-heading);
  font-weight: 700;
}

.markdown-prose tr:hover td {
  background-color: var(--bg-card-hover);
}

/* Code Blocks */
.markdown-prose code {
  font-family: var(--font-code);
  font-size: 0.86em;
  background-color: var(--inline-code-bg);
  color: var(--inline-code-text);
  padding: 2px 5px;
  border-radius: 3px;
}

.code-block-wrapper {
  margin: 16px 0;
  background-color: var(--code-bg);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-md);
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 5px 12px;
  background-color: rgba(255, 255, 255, 0.05);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.code-lang-label {
  font-family: var(--font-code);
  font-size: 0.7rem;
  font-weight: 600;
  color: #94A3B8;
  text-transform: uppercase;
}

.copy-code-btn {
  background: rgba(255, 255, 255, 0.12);
  border: none;
  color: #F8FAFC;
  padding: 2px 7px;
  border-radius: 3px;
  font-size: 0.7rem;
  font-weight: 600;
  cursor: pointer;
}

.copy-code-btn:hover {
  background: var(--accent-primary);
}

.markdown-prose pre {
  margin: 0;
  padding: 12px 16px;
  overflow-x: auto;
}

.markdown-prose pre code {
  background-color: transparent;
  color: var(--code-text);
  padding: 0;
  font-size: 0.86rem;
  line-height: 1.5;
}

/* Coming Soon Teasers */
.coming-soon-hero {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 28px 24px;
  text-align: center;
  margin-bottom: 20px;
  box-shadow: var(--shadow-sm);
}

.coming-soon-badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 3px 10px;
  border-radius: var(--radius-pill);
  background-color: var(--accent-primary);
  color: white;
  font-size: 0.74rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.coming-soon-title {
  font-family: var(--font-heading);
  font-size: 1.45rem;
  font-weight: 800;
  margin-bottom: 6px;
}

.coming-soon-desc {
  color: var(--text-muted);
  max-width: 500px;
  margin: 0 auto 14px auto;
  font-size: 0.9rem;
}

.sneak-peek-grid {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 16px;
}

.sneak-peek-item {
  background-color: var(--bg-app);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  display: flex;
  align-items: flex-start;
  gap: 10px;
  text-align: left;
}

.q-number-pill {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background-color: var(--accent-soft);
  color: var(--accent-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.76rem;
  flex-shrink: 0;
}

.q-text {
  font-weight: 600;
  font-size: 0.88rem;
  color: var(--text-main);
  line-height: 1.4;
}

/* Table of Contents */
.toc-sidebar {
  width: 230px;
  height: 100%;
  padding: 28px 16px 24px 8px;
  overflow-y: auto;
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
  user-select: none;
}

.toc-title {
  font-family: var(--font-heading);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--text-subtle);
}

.toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.toc-item a {
  display: block;
  font-size: 0.8rem;
  color: var(--text-muted);
  text-decoration: none;
  padding: 3px 6px;
  border-radius: var(--radius-sm);
  line-height: 1.35;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.toc-item a:hover {
  color: var(--accent-primary);
  background-color: var(--bg-sidebar-hover);
}

.toc-item.level-3 a {
  padding-left: 14px;
  font-size: 0.76rem;
}

/* Fullscreen Mode */
.app-container.fullscreen-mode .sidebar,
.app-container.fullscreen-mode .topic-list-panel {
  display: none !important;
}

.app-container.fullscreen-mode .note-canvas-panel {
  width: 100vw !important;
  max-width: 100vw !important;
}

.app-container.fullscreen-mode .markdown-prose-container {
  max-width: 920px !important;
}

.app-container.fullscreen-mode .canvas-toolbar {
  padding: 0 40px;
}

/* Modals */
.modal-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(15, 23, 42, 0.45);
  backdrop-filter: blur(4px);
  z-index: 100;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 16px;
}

.modal-backdrop.open {
  display: flex;
}

.modal-dialog {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 500px;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

.modal-header {
  padding: 16px 18px;
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-title {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 700;
}

.modal-close-btn {
  background: transparent;
  border: none;
  font-size: 1.1rem;
  color: var(--text-muted);
  cursor: pointer;
}

.modal-body {
  padding: 18px;
}

.calc-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 14px;
}

.calc-box {
  background-color: var(--bg-app);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 10px;
}

.calc-label {
  font-size: 0.74rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 3px;
}

.calc-input {
  width: 100%;
  padding: 5px 8px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 4px;
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-main);
  outline: none;
}

.calc-input:focus {
  border-color: var(--accent-primary);
}

.calc-results-card {
  background: var(--bg-app);
  border: 1px solid var(--accent-primary);
  border-radius: var(--radius-sm);
  padding: 14px;
  text-align: center;
}

.res-cgpa {
  font-family: var(--font-heading);
  font-size: 2.1rem;
  font-weight: 800;
  color: var(--accent-primary);
  line-height: 1.1;
  margin: 4px 0;
}

/* Mobile Bottom Bar */
.mobile-bottom-bar {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 52px;
  background-color: var(--bg-card);
  border-top: 1px solid var(--border-subtle);
  z-index: 60;
  justify-content: space-around;
  align-items: center;
}

.mobile-nav-btn {
  background: transparent;
  border: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
}

.mobile-nav-btn.active {
  color: var(--accent-primary);
}

/* Responsive */
@media (max-width: 1100px) {
  .toc-sidebar {
    display: none;
  }
  .markdown-scroll-container {
    padding: 20px 24px 40px 24px;
  }
}

@media (max-width: 860px) {
  .sidebar {
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    transform: translateX(-100%);
    box-shadow: var(--shadow-lg);
  }
  .sidebar.open {
    transform: translateX(0);
  }
  .mobile-menu-btn {
    display: flex;
  }
  .topic-list-panel {
    width: 300px;
  }
}

@media (max-width: 640px) {
  .app-container {
    flex-direction: column;
    padding-bottom: 52px;
  }
  .mobile-bottom-bar {
    display: flex;
  }
  .topic-list-panel {
    width: 100%;
    height: 100%;
  }
  .topic-list-panel.hidden-mobile {
    display: none;
  }
  .note-canvas-panel {
    display: none;
    width: 100%;
    height: 100%;
  }
  .note-canvas-panel.active-mobile {
    display: flex;
  }
  .markdown-scroll-container {
    padding: 14px 14px 36px 14px;
  }
  .canvas-toolbar {
    padding: 0 12px;
  }
}