/*
 *  Software Engineering Economics — shared slide styling
 *  Dr. Zhijiang Chen · Beijing Jiaotong University · Summer 2026
 */

:root {
  --ink:        #1A1A2E;
  --ink-soft:   #4A4A5E;
  --ink-mute:   #7A7A8A;
  --paper:      #FAF8F4;
  --paper-warm: #F3EFE6;
  --rule:       #D4CFC3;
  --rule-soft:  #E8E3D5;
  --indigo:     #3F51B5;
  --indigo-dk:  #283593;
  --indigo-lt:  #E8EAF6;
  --crimson:    #B73239;
  --amber:      #C77D00;
  --green-dk:   #2E7D32;
}

html, body { background: var(--paper); }

.reveal {
  font-family: 'Crimson Pro', 'Georgia', serif;
  font-size: 30px;
  color: var(--ink);
  font-feature-settings: "kern", "liga", "calt", "onum";
}

.reveal .slides { text-align: left; }

.reveal .slides > section {
  padding: 70px 80px 60px;
  box-sizing: border-box;
  height: 100%;
}

/* ---------- Global header / footer banner (every slide) ---------- */
.reveal .slides > section::before {
  content: "Beijing Jiaotong University  ·  Summer 2026";
  position: absolute;
  top: 16px; left: 80px; right: 80px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--ink-mute);
  text-align: center;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--rule-soft);
  pointer-events: none;
}
.reveal .slides > section::after {
  content: "Dr. Zhijiang Chen";
  position: absolute;
  bottom: 14px; left: 80px; right: 80px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--ink-mute);
  text-align: center;
  padding-top: 8px;
  border-top: 1px solid var(--rule-soft);
  pointer-events: none;
}
.reveal .slides > section.divider::before,
.reveal .slides > section.divider::after,
.reveal .slides > section.discussion::before,
.reveal .slides > section.discussion::after {
  color: rgba(250,248,244,0.6);
  border-color: rgba(250,248,244,0.22);
}

/* ---------- Typography ---------- */
.reveal h1, .reveal h2, .reveal h3 {
  font-family: 'Fraunces', 'Crimson Pro', serif;
  font-weight: 500;
  color: var(--ink);
  letter-spacing: -0.02em;
  text-transform: none;
  margin: 0 0 0.55em;
  line-height: 1.1;
}
.reveal h1 { font-size: 2.0em; font-weight: 400; font-variation-settings: "SOFT" 30; }
.reveal h2 { font-size: 1.65em; font-weight: 450; }
.reveal h3 { font-size: 1.15em; font-weight: 500; color: var(--ink-soft); }

.reveal p, .reveal li { line-height: 1.5; }
.reveal p { margin: 0 0 0.7em; }
.reveal ul, .reveal ol { margin: 0.2em 0 0.6em 1.2em; }
.reveal ul li { list-style: none; position: relative; padding-left: 1.3em; margin-bottom: 0.35em; }
.reveal ul li::before {
  content: ""; position: absolute; left: 0; top: 0.62em;
  width: 0.85em; height: 1px; background: var(--indigo);
}
.reveal ol { list-style-type: none; counter-reset: ord; padding-left: 0; }
.reveal ol li {
  counter-increment: ord;
  padding-left: 2.3em;
  margin-bottom: 0.45em;
  position: relative;
}
.reveal ol li::before {
  content: counter(ord, decimal-leading-zero);
  position: absolute; left: 0; top: 0.05em;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.6em; color: var(--indigo); font-weight: 600;
  letter-spacing: 0.05em;
}

.reveal em { color: var(--indigo-dk); font-style: italic; }
.reveal strong { font-weight: 600; color: var(--ink); }

code, .mono {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8em;
}

/* ---------- Editorial frame ---------- */
.slide-meta {
  position: absolute; top: 48px; left: 80px; right: 80px;
  display: flex; justify-content: space-between;
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-mute);
  pointer-events: none;
}
.slide-meta .left  { display: flex; gap: 24px; align-items: center; }
.slide-meta .right { display: flex; gap: 24px; align-items: center; }
.slide-meta .dot   {
  display: inline-block; width: 6px; height: 6px;
  border-radius: 50%; background: var(--indigo);
  vertical-align: middle; margin: 0 2px 3px;
}
.slide-foot {
  position: absolute; bottom: 44px; left: 80px; right: 80px;
  display: flex; justify-content: space-between; align-items: baseline;
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px; letter-spacing: 0.18em;
  text-transform: uppercase; color: var(--ink-mute);
  padding-top: 6px;
  pointer-events: none;
}
.slide-foot .course { color: var(--ink-soft); font-weight: 500; }

/* ---------- Title slide ---------- */
.cover {
  background:
    radial-gradient(circle at 80% 10%, rgba(63,81,181,0.07), transparent 40%),
    linear-gradient(180deg, var(--paper) 0%, var(--paper-warm) 100%);
}
.cover-grid {
  display: grid; grid-template-columns: 1.05fr 1fr; gap: 48px;
  height: 100%;
  align-items: stretch;
  padding: 0;
}
.cover-left { align-self: center; }
.cover-eyebrow {
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px; letter-spacing: 0.3em; text-transform: uppercase;
  color: var(--indigo); margin-bottom: 18px;
}
.cover-title {
  font-family: 'Fraunces', serif;
  font-weight: 350;
  font-size: 2.7em;
  font-variation-settings: "SOFT" 40;
  line-height: 1.02;
  letter-spacing: -0.025em;
  color: var(--ink);
  margin: 0 0 0.3em;
}
.cover-title .accent { color: var(--indigo); font-style: italic; font-weight: 400; }
.cover-rule { width: 68px; height: 2px; background: var(--indigo); margin: 22px 0 18px; }
.cover-sub {
  font-family: 'Crimson Pro', serif; font-style: italic;
  font-size: 1.02em; color: var(--ink-soft); max-width: 22em; line-height: 1.42;
}
.cover-right { align-self: center; border-left: 1px solid var(--rule); padding-left: 38px; }
.cover-meta-row {
  display: grid; grid-template-columns: 1fr 1fr; gap: 14px 24px;
  margin-bottom: 18px;
}
.cover-meta-row .label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 9.5px; letter-spacing: 0.22em; text-transform: uppercase;
  color: var(--ink-mute); margin-bottom: 3px;
}
.cover-meta-row .value {
  font-family: 'Fraunces', serif; font-weight: 400;
  font-size: 0.95em; color: var(--ink);
}
.cover-volume {
  font-family: 'Fraunces', serif;
  font-size: 4.4em; font-weight: 200;
  font-variation-settings: "SOFT" 80, "opsz" 144;
  color: var(--indigo);
  line-height: 0.9;
  letter-spacing: -0.05em;
  margin-bottom: 10px;
}
.cover-volume .small {
  font-size: 0.2em; vertical-align: top;
  letter-spacing: 0.3em; text-transform: uppercase;
  color: var(--ink-mute); margin-left: 10px;
  font-family: 'JetBrains Mono', monospace;
  display: inline-block; padding-top: 10px;
}

/* ---------- Section divider ---------- */
.divider {
  background: linear-gradient(135deg, var(--indigo) 0%, var(--indigo-dk) 100%);
  color: var(--paper);
}
.divider .slide-meta,
.divider .slide-foot { color: rgba(250,248,244,0.55); border-color: rgba(250,248,244,0.2); }
.divider .slide-meta .dot { background: var(--paper); }
.divider-content {
  display: flex; flex-direction: column;
  justify-content: center; align-items: flex-start;
  height: 100%;
}
.divider-roman {
  font-family: 'JetBrains Mono', monospace;
  font-size: 13px; letter-spacing: 0.4em;
  color: rgba(250,248,244,0.6);
  margin-bottom: 24px;
  text-transform: uppercase;
}
.divider-number {
  font-family: 'Fraunces', serif;
  font-weight: 200;
  font-variation-settings: "SOFT" 60, "opsz" 144;
  font-size: 10em;
  line-height: 0.85;
  letter-spacing: -0.06em;
  color: var(--paper);
  margin-bottom: 0;
}
.divider-title {
  font-family: 'Fraunces', serif;
  font-weight: 350;
  font-size: 2.2em;
  letter-spacing: -0.02em;
  color: var(--paper);
  margin: 8px 0 22px;
  max-width: 18em;
}
.divider-title em { color: rgba(255,255,255,0.85); font-style: italic; }
.divider-quote {
  font-family: 'Crimson Pro', serif;
  font-style: italic;
  font-size: 1.05em;
  color: rgba(250,248,244,0.7);
  max-width: 26em;
  border-left: 2px solid rgba(250,248,244,0.4);
  padding-left: 18px;
}

/* ---------- Discussion slide (warm amber background) ---------- */
.discussion {
  background:
    radial-gradient(circle at 20% 80%, rgba(199,125,0,0.10), transparent 50%),
    linear-gradient(160deg, #2A2418 0%, #1F1A12 100%);
  color: #F5EDD8;
}
.discussion h1, .discussion h2 { color: #F5EDD8; }
.discussion .label-tag { color: var(--amber); }
.discussion .lede { color: #D8CBA6; }
.discussion ol li, .discussion ul li { color: #ECE3CB; }
.discussion ol li::before { color: var(--amber); }
.discussion ul li::before { background: var(--amber); }
.discussion .footnote { color: rgba(245,237,216,0.55); }
.discussion .slide-meta, .discussion .slide-foot { color: rgba(245,237,216,0.55); }
.discussion em { color: #F0CC7A; }
.discussion strong { color: #F5EDD8; }
.discussion-icon {
  display: inline-block;
  font-family: 'Fraunces', serif; font-style: italic;
  font-weight: 200; color: var(--amber);
  font-size: 9em; line-height: 0.85;
  letter-spacing: -0.08em; margin-bottom: 0;
}

/* ---------- Pull quote slide ---------- */
.pullquote {
  display: flex; flex-direction: column;
  justify-content: center;
  height: 100%;
  padding: 80px 140px;
}
.pullquote blockquote {
  font-family: 'Fraunces', serif;
  font-style: italic;
  font-weight: 350;
  font-size: 2.1em;
  line-height: 1.18;
  letter-spacing: -0.015em;
  color: var(--ink);
  border: none; margin: 0 0 30px;
  padding: 0;
}
.pullquote blockquote::before {
  content: "“";
  font-family: 'Fraunces', serif;
  font-size: 3em; line-height: 0.6;
  color: var(--indigo);
  display: block;
  margin-bottom: 0.1em;
}
.pullquote cite {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px; letter-spacing: 0.2em;
  text-transform: uppercase; color: var(--ink-mute);
  font-style: normal;
}

/* ---------- Tables ---------- */
.reveal table {
  width: 100%;
  border-collapse: collapse;
  margin: 14px 0 10px;
  font-feature-settings: "tnum", "lnum";
}
.reveal table thead th {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10.5px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-mute);
  font-weight: 500;
  text-align: left;
  padding: 8px 16px 8px 0;
  border-bottom: 1.5px solid var(--ink);
  vertical-align: bottom;
}
.reveal table tbody td {
  padding: 10px 16px 10px 0;
  border-bottom: 1px solid var(--rule-soft);
  vertical-align: top;
  color: var(--ink);
  font-size: 0.78em;
  line-height: 1.42;
}
.reveal table tbody td.num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72em;
  color: var(--ink-soft);
}
.reveal table tbody td.label {
  font-weight: 600; white-space: nowrap;
}
.reveal table.compact tbody td { padding: 7px 12px 7px 0; font-size: 0.74em; }

/* ---------- Layout helpers ---------- */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr; gap: 50px;
  align-items: start;
}
.three-col {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr; gap: 36px;
  align-items: start;
}
.four-col {
  display: grid;
  grid-template-columns: repeat(4, 1fr); gap: 28px;
  align-items: start;
}

.label-tag {
  display: inline-block;
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px; letter-spacing: 0.22em;
  text-transform: uppercase; color: var(--indigo);
  margin-bottom: 12px;
}

.lede {
  font-family: 'Crimson Pro', serif;
  font-style: italic;
  font-size: 1.08em;
  color: var(--ink-soft);
  line-height: 1.45;
  max-width: 28em;
  margin: 0 0 0.9em;
}

.footnote {
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  color: var(--ink-mute);
  letter-spacing: 0.05em;
  margin-top: 14px;
}

/* ---------- Card / box ---------- */
.card {
  background: var(--paper-warm);
  border: 1px solid var(--rule-soft);
  padding: 16px 20px;
  border-radius: 2px;
}
.card h3 { margin-bottom: 8px; font-size: 0.95em; color: var(--indigo-dk); }
.card p, .card ul li { font-size: 0.82em; line-height: 1.42; margin: 0; }
.card.accent { background: var(--indigo-lt); border-color: var(--indigo); }
.card.accent h3 { color: var(--indigo-dk); }

.callout {
  border-left: 3px solid var(--indigo);
  padding: 4px 0 4px 20px;
  margin: 12px 0;
  color: var(--ink-soft);
  font-style: italic;
  font-size: 0.9em;
}

.formula {
  font-family: 'JetBrains Mono', monospace;
  background: var(--paper-warm);
  border: 1px solid var(--rule-soft);
  border-radius: 3px;
  padding: 14px 22px;
  font-size: 0.85em;
  color: var(--indigo-dk);
  margin: 10px 0;
  text-align: center;
}

/* ---------- Stat / number callout ---------- */
.big-stat {
  font-family: 'Fraunces', serif;
  font-variation-settings: "SOFT" 70;
  font-weight: 250;
  font-size: 4.2em;
  line-height: 1;
  color: var(--indigo);
  letter-spacing: -0.04em;
}
.big-stat .unit {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.18em; color: var(--ink-mute);
  letter-spacing: 0.2em; text-transform: uppercase;
  vertical-align: top; margin-left: 8px;
  padding-top: 1.6em; display: inline-block;
}

/* ---------- Final / Q&A slide ---------- */
.end {
  display: flex; flex-direction: column;
  justify-content: center; align-items: center;
  height: 100%; text-align: center;
}
.end .ampersand {
  font-family: 'Fraunces', serif; font-weight: 200;
  font-style: italic;
  font-variation-settings: "SOFT" 90;
  font-size: 14em; line-height: 1;
  color: var(--indigo);
  letter-spacing: -0.08em;
}
.end h2 {
  font-family: 'Fraunces', serif; font-weight: 400;
  font-size: 1.9em; margin-top: -20px;
}
.end .sig {
  font-family: 'Crimson Pro', serif; font-style: italic;
  font-size: 0.95em; color: var(--ink-mute);
  margin-top: 22px; letter-spacing: 0.02em;
}

/* ---------- Progress bar ---------- */
.reveal .progress {
  background: var(--rule-soft);
  height: 3px;
  color: var(--indigo);
}
.reveal .progress span { background: var(--indigo); }

.reveal .slide-number {
  background: transparent;
  color: var(--ink-mute);
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  letter-spacing: 0.18em;
  bottom: 12px; right: 16px;
}

/* ---------- MathJax / formulas ---------- */
mjx-container { font-size: 0.95em !important; color: var(--indigo-dk) !important; }