/* ============================================
   TurboQuant — Light Academic Theme
   Inspired by LaTeX papers & technical docs
   ============================================ */

:root {
  --bg: #fcfcfa;
  --bg-code: #f5f5f0;
  --bg-blockquote: #f0f4f8;
  --bg-header: #ffffff;
  --bg-table-head: #f7f7f5;
  --bg-table-hover: #fafaf8;
  --bg-nav: rgba(252,252,250,0.95);
  --bg-btn: #ffffff;
  --bg-btn-hover: #f5f5f0;
  --bg-badge: #eef2ff;
  --bg-toc-hover: #f7f7f5;

  --text: #1a1a1a;
  --text-secondary: #4a4a4a;
  --text-muted: #777777;
  --text-code: #c7254e;

  --accent: #2563eb;
  --accent-light: #dbeafe;
  --accent-dark: #1d4ed8;
  --border: #e5e5e0;
  --border-light: #eeeeea;
  --border-code: #ddddd8;
  --rule: #cccccc;

  --font-serif: 'Source Serif 4', 'Palatino Linotype', Palatino, 'Book Antiqua', Georgia, serif;
  --font-sans: 'Source Sans 3', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --font-mono: 'Source Code Pro', 'Menlo', 'Consolas', 'DejaVu Sans Mono', monospace;

  --max-width: 740px;
  --transition: 0.15s ease;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 18px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-serif);
  line-height: 1.75;
  min-height: 100vh;
}

::selection {
  background: var(--accent-light);
  color: var(--text);
}

/* ============================================
   LANDING PAGE
   ============================================ */

.landing {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
}

.landing-bg {
  display: none;
}

.landing-content {
  max-width: 640px;
  width: 100%;
}

.landing-badge {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--bg-badge);
  padding: 0.3rem 0.8rem;
  border-radius: 3px;
  margin-bottom: 1.5rem;
}

.landing-title {
  font-family: var(--font-serif);
  font-size: clamp(2.5rem, 6vw, 3.5rem);
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 0.75rem;
  color: var(--text);
  letter-spacing: -0.02em;
}

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

.landing-subtitle {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-style: italic;
  color: var(--text-secondary);
  line-height: 1.5;
  margin-bottom: 0.5rem;
}

.landing-paper {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}

.landing-paper a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

img.landing-hero {
  display: block;
  max-width: 420px;
  width: 100%;
  height: auto;
  border-radius: 6px;
  border: 1px solid var(--border);
  margin: 0 auto 2rem;
}

.landing-meta {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 2.5rem;
  font-family: var(--font-sans);
  font-size: 0.78rem;
  color: var(--text-muted);
}

.meta-item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.meta-icon {
  font-size: 0.9rem;
  opacity: 0.6;
}

/* Table of Contents */

.toc {
  margin-bottom: 2.5rem;
  border-top: 2px solid var(--text);
  padding-top: 1.5rem;
}

.toc-part {
  margin-bottom: 1.25rem;
}

.toc-part-label {
  font-family: var(--font-sans);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 0 0.5rem;
  margin-bottom: 0.35rem;
}

.toc-entry {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  padding: 0.45rem 0.5rem;
  border-radius: 4px;
  text-decoration: none;
  color: var(--text);
  transition: background var(--transition);
}

.toc-entry:hover {
  background: var(--bg-toc-hover);
}

.toc-number {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-muted);
  min-width: 1.5rem;
}

.toc-title {
  font-family: var(--font-serif);
  font-size: 0.95rem;
}

.toc-entry:hover .toc-title {
  color: var(--accent);
}

.start-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  color: #ffffff;
  background: var(--accent);
  padding: 0.7rem 1.6rem;
  border-radius: 4px;
  text-decoration: none;
  transition: background var(--transition);
  border: none;
}

.start-btn:hover {
  background: var(--accent-dark);
}

.start-btn .arrow {
  transition: transform var(--transition);
}

.start-btn:hover .arrow {
  transform: translateX(3px);
}

/* ============================================
   SLIDE PAGE
   ============================================ */

.slide-wrapper {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Top nav — thin, understated */
.slide-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.5rem 1.5rem;
  background: var(--bg-nav);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  font-family: var(--font-sans);
}

.nav-home {
  text-decoration: none;
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--text);
  flex-shrink: 0;
}

.logo-accent {
  color: var(--accent);
}

.nav-progress-container {
  flex: 1;
  height: 2px;
  background: var(--border-light);
  border-radius: 2px;
  overflow: hidden;
}

.nav-progress-bar {
  height: 100%;
  background: var(--accent);
  border-radius: 2px;
  transition: width 0.4s ease;
}

.nav-info {
  font-size: 0.72rem;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  flex-shrink: 0;
}

/* Part label */
.part-label {
  text-align: center;
  font-family: var(--font-sans);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 1.5rem 0 0;
}

/* Slide content — the reading experience */
.slide-content {
  flex: 1;
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem 1.5rem 4rem;
}

.slide-header {
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.section-number {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  display: block;
  margin-bottom: 0.3rem;
}

.slide-header h1 {
  font-family: var(--font-serif);
  font-size: clamp(1.5rem, 3.5vw, 2rem);
  font-weight: 700;
  line-height: 1.25;
  color: var(--text);
  letter-spacing: -0.01em;
}

/* Body content — designed for reading */

.slide-body h2 {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 700;
  margin: 2.5rem 0 0.75rem;
  color: var(--text);
  letter-spacing: -0.01em;
}

.slide-body h3 {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 700;
  margin: 1.75rem 0 0.5rem;
  color: var(--text);
}

.slide-body p {
  margin-bottom: 1rem;
}

.slide-body strong {
  font-weight: 700;
  color: var(--text);
}

.slide-body em {
  font-style: italic;
}

.slide-body a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
  text-decoration-thickness: 1px;
}

.slide-body a:hover {
  text-decoration-thickness: 2px;
}

/* Blockquotes — key insight callouts */
.slide-body blockquote {
  margin: 1.5rem 0;
  padding: 0.9rem 1.2rem;
  background: var(--bg-blockquote);
  border-left: 3px solid var(--accent);
  border-radius: 0 4px 4px 0;
}

.slide-body blockquote p {
  color: var(--text);
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}

.slide-body blockquote p:last-child {
  margin-bottom: 0;
}

/* Inline code */
.slide-body code {
  font-family: var(--font-mono);
  font-size: 0.82em;
  background: var(--bg-code);
  color: var(--text-code);
  padding: 0.15em 0.35em;
  border-radius: 3px;
  border: 1px solid var(--border-code);
}

/* Code blocks */
.slide-body pre {
  margin: 1.25rem 0;
  padding: 1rem 1.2rem;
  background: var(--bg-code);
  border: 1px solid var(--border-code);
  border-radius: 4px;
  overflow-x: auto;
  line-height: 1.5;
}

.slide-body pre code {
  background: none;
  border: none;
  padding: 0;
  color: var(--text);
  font-size: 0.8rem;
}

/* Tables — clean academic style */
.slide-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.88rem;
  font-family: var(--font-sans);
}

.slide-body th {
  font-weight: 600;
  font-size: 0.78rem;
  text-align: left;
  padding: 0.6rem 0.8rem;
  background: var(--bg-table-head);
  border-bottom: 2px solid var(--text);
  color: var(--text);
}

.slide-body td {
  padding: 0.55rem 0.8rem;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}

.slide-body tr:hover td {
  background: var(--bg-table-hover);
}

/* Lists */
.slide-body ul, .slide-body ol {
  margin: 0.75rem 0 1rem;
  padding-left: 1.5rem;
}

.slide-body li {
  margin-bottom: 0.35rem;
}

/* Images / SVG figures */
.slide-body img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 1.75rem auto;
  border-radius: 4px;
}

.slide-body .figure-caption {
  text-align: center;
  font-family: var(--font-sans);
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: -1rem;
  margin-bottom: 1.5rem;
}

/* Images */
.slide-body img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 1.5rem auto;
  border-radius: 6px;
  border: 1px solid var(--border);
}

/* Horizontal rules — thin section dividers */
.slide-body hr {
  border: none;
  height: 1px;
  background: var(--border);
  margin: 2.5rem 0;
}

/* ============================================
   BOTTOM NAVIGATION
   ============================================ */

.slide-footer {
  display: flex;
  justify-content: space-between;
  padding: 0.75rem 1.5rem;
  background: var(--bg-header);
  border-top: 1px solid var(--border);
  gap: 1rem;
  font-family: var(--font-sans);
}

.nav-btn {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  padding: 0.6rem 0.9rem;
  border-radius: 4px;
  border: 1px solid var(--border);
  background: var(--bg-btn);
  transition: all var(--transition);
  max-width: 50%;
}

.nav-btn:hover {
  border-color: var(--accent);
  background: var(--bg-btn-hover);
}

.nav-prev { margin-right: auto; }
.nav-next { margin-left: auto; }

.nav-arrow {
  font-size: 1rem;
  color: var(--accent);
  flex-shrink: 0;
}

.nav-label {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.nav-direction {
  font-size: 0.6rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.nav-target {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* ============================================
   KEYBOARD HINT
   ============================================ */

.kbd-hint {
  position: fixed;
  bottom: 0.75rem;
  right: 0.75rem;
  font-family: var(--font-sans);
  font-size: 0.6rem;
  color: var(--text-muted);
  background: var(--bg-header);
  padding: 0.3rem 0.6rem;
  border-radius: 4px;
  border: 1px solid var(--border);
  opacity: 0.5;
  transition: opacity var(--transition);
  z-index: 50;
}

.kbd-hint:hover {
  opacity: 1;
}

kbd {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.6rem;
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 2px;
  padding: 0.05rem 0.3rem;
  margin: 0 0.1rem;
}

/* ============================================
   RESPONSIVE
   ============================================ */

@media (max-width: 768px) {
  html { font-size: 16px; }
  .landing { padding: 1.5rem; }
  .slide-content { padding: 1.25rem 1rem 3rem; }
  .slide-nav { padding: 0.4rem 1rem; }
  .slide-footer { padding: 0.6rem 1rem; }
  .toc-entry { padding: 0.4rem; }
  .nav-target { max-width: 120px; }
  .kbd-hint { display: none; }
}

@media (max-width: 480px) {
  .landing-meta { flex-direction: column; gap: 0.4rem; }
}

/* ============================================
   PRINT — looks good on paper
   ============================================ */

@media print {
  .slide-nav, .slide-footer, .kbd-hint { display: none; }
  .slide-content { max-width: 100%; padding: 0; }
  .slide-body pre { border: 1px solid #ccc; }
}