:root {
  --ink: #ECEDF1;
  --ink-soft: #9BA1AC;
  --ink-faint: #555C68;
  --paper: #0E1117;
  --surface: #161B24;
  --line: #232A38;
  --accent: #7C8CFF;
  --accent2: #56E0C4;
  --accent-glow: rgba(124,140,255,0.18);
  --accent-tint: rgba(124,140,255,0.30);
  --font-display: 'Space Grotesk', sans-serif;
  --font-body: 'Inter', system-ui, sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;
  --font-fa: 'Vazirmatn', sans-serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  transition: font-family .2s;
}

body.fa {
  font-family: var(--font-fa);
  direction: rtl;
}

body.fa .font-display,
body.fa h1, body.fa h2, body.fa h3,
body.fa .section-title, body.fa .role,
body.fa .layer-name {
  font-family: var(--font-fa);
}

a { color: inherit; text-decoration: none; }

/* ── LANG TOGGLE ── */
.lang-toggle {
  position: fixed;
  top: 20px; right: 24px;
  z-index: 100;
  width: 48px; height: 28px;
  background: var(--surface);
  border: 1px solid var(--accent-tint);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 11px; font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--accent);
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: background .2s, box-shadow .2s, border-color .2s, transform .15s;
  box-shadow: 0 0 12px var(--accent-glow);
}
.lang-toggle:hover {
  background: rgba(124,140,255,0.12);
  box-shadow: 0 0 24px var(--accent-glow);
  transform: scale(1.06);
}
.lang-toggle:active { transform: scale(0.96); }
.lang-toggle .lang-fa { display: none; }
body.fa .lang-toggle .lang-en { display: none; }
body.fa .lang-toggle .lang-fa { display: inline; }

/* ── CANVAS BG ── */
#bg-canvas {
  position: fixed; inset: 0;
  width: 100%; height: 100%;
  pointer-events: none;
  z-index: 0; opacity: 0.5;
}

/* ── PAGE LAYOUT ── */
.page {
  position: relative; z-index: 1;
  display: grid;
  grid-template-columns: 300px 1fr;
  max-width: 1200px;
  margin: 0 auto;
  min-height: 100vh;
}

/* ── SIDEBAR ── */
.sidebar {
  position: sticky; top: 0; align-self: start;
  height: 100vh;
  padding: 52px 36px 36px;
  border-right: 1px solid var(--line);
  display: flex; flex-direction: column;
  backdrop-filter: blur(12px);
  background: rgba(14,17,23,0.78);
}
body.fa .sidebar { border-right: none; border-left: 1px solid var(--line); }

.monogram {
  width: 54px; height: 54px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-display);
  font-weight: 700; font-size: 19px;
  margin-bottom: 22px;
  box-shadow: 0 0 28px var(--accent-glow);
}

.identity h1 {
  font-family: var(--font-display);
  font-size: 28px; font-weight: 700;
  line-height: 1.18; letter-spacing: -0.01em;
  margin-bottom: 6px; min-height: 1.3em;
}
body.fa .identity h1 { font-family: var(--font-fa); letter-spacing: 0; }

.tw-cursor {
  display: inline-block;
  color: var(--accent);
  animation: blink 1s step-end infinite;
  font-weight: 300;
}
@keyframes blink { 0%,100%{opacity:1} 50%{opacity:0} }

.role {
  font-family: var(--font-mono);
  font-size: 12px; text-transform: uppercase;
  letter-spacing: 0.1em; color: var(--accent);
  font-weight: 500; margin-bottom: 36px;
}
body.fa .role { font-family: var(--font-fa); text-transform: none; letter-spacing: 0; font-size: 13px; }

/* contact */
.contact-list {
  list-style: none;
  display: flex; flex-direction: column; gap: 14px;
  margin-bottom: 36px;
}
.contact-list li { display: flex; flex-direction: column; gap: 2px; }
.contact-list .label {
  font-family: var(--font-mono); font-size: 10px;
  text-transform: uppercase; letter-spacing: 0.07em; color: var(--ink-faint);
}
body.fa .contact-list .label { font-family: var(--font-fa); text-transform: none; font-size: 11px; letter-spacing: 0; }
.contact-list a, .contact-list span:not(.label) { font-size: 13.5px; color: var(--ink); }
.contact-list a {
  width: fit-content; position: relative; padding-bottom: 1px;
}
.contact-list a::after {
  content: ''; position: absolute; bottom: 0; left: 0;
  width: 0; height: 1px; background: var(--accent);
  transition: width .25s;
}
.contact-list a:hover::after { width: 100%; }
.contact-list a:hover { color: var(--accent); }

/* nav */
.index-nav { display: flex; flex-direction: column; gap: 2px; margin-bottom: auto; }
.index-nav a {
  display: flex; align-items: center; gap: 10px;
  padding: 9px 0; font-size: 13.5px; font-weight: 500;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--line);
  transition: color .15s, padding-left .15s;
  border-radius: 4px;
}
body.fa .index-nav a { gap: 10px; }
.index-nav a:first-child { border-top: 1px solid var(--line); }
.index-nav .num { font-family: var(--font-mono); font-size: 10.5px; color: var(--ink-faint); }
.index-nav a:hover { color: var(--ink); padding-left: 5px; }
body.fa .index-nav a:hover { padding-left: 0; padding-right: 5px; }
.index-nav a.active { color: var(--accent); }
.index-nav a.active .num { color: var(--accent); }

/* print btn */
.print-btn {
  margin-top: 28px;
  display: flex; align-items: center; justify-content: center; gap: 8px;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  color: #0E1117; border: none; border-radius: 8px;
  padding: 13px 18px;
  font-family: var(--font-body); font-size: 13px; font-weight: 700;
  cursor: pointer;
  transition: opacity .2s, transform .15s, box-shadow .2s;
  box-shadow: 0 0 24px var(--accent-glow);
}
body.fa .print-btn { font-family: var(--font-fa); }
.print-btn:hover { opacity: 0.88; box-shadow: 0 0 40px var(--accent-glow); }
.print-btn:active { transform: scale(0.97); }
.arr { transition: transform .15s; }
.print-btn:hover .arr { transform: translateX(4px); }
body.fa .print-btn:hover .arr { transform: translateX(-4px); }

/* ── MAIN ── */
.content { padding: 64px 56px 100px; }

.section {
  margin-bottom: 88px;
  opacity: 0; transform: translateY(20px);
  transition: opacity .6s, transform .6s;
}
.section.in-view { opacity: 1; transform: translateY(0); }

.section-title {
  display: flex; align-items: baseline; gap: 14px;
  font-family: var(--font-display);
  font-size: 32px; font-weight: 700;
  margin-bottom: 36px; letter-spacing: -0.01em;
}
body.fa .section-title { font-family: var(--font-fa); letter-spacing: 0; }

.eyebrow { font-family: var(--font-mono); font-size: 13px; font-weight: 500; color: var(--accent); }

.about-text { font-size: 16px; line-height: 1.85; color: var(--ink-soft); max-width: 640px; }
body.fa .about-text { line-height: 2.1; }

.section-intro { font-size: 15px; color: var(--ink-soft); margin-bottom: 28px; }

/* ── TIMELINE ── */
.timeline { display: flex; flex-direction: column; }

.entry {
  display: grid; grid-template-columns: 130px 1fr;
  gap: 32px; padding: 28px 0;
  border-top: 1px solid var(--line);
  position: relative;
}
.entry::before {
  content: ''; position: absolute;
  left: -1px; top: 0; width: 2px; height: 0;
  background: linear-gradient(to bottom, var(--accent), transparent);
  transition: height .6s;
}
body.fa .entry::before { left: auto; right: -1px; }
.entry.in-view::before { height: 100%; }

.year { font-family: var(--font-mono); font-size: 13px; color: var(--ink-soft); padding-top: 3px; }
body.fa .year { font-family: var(--font-fa); font-size: 13px; }

.entry-body h3 {
  font-family: var(--font-display);
  font-size: 18px; font-weight: 600;
  margin-bottom: 4px; letter-spacing: -0.01em;
}
body.fa .entry-body h3 { font-family: var(--font-fa); letter-spacing: 0; }

.entry-org { font-size: 13.5px; color: var(--accent); font-weight: 500; margin-bottom: 14px; }

.entry-link { color: var(--accent); border-bottom: 1px solid transparent; transition: border-color .15s; }
.entry-link:hover { border-bottom-color: var(--accent); }

.entry-body ul { list-style: none; display: flex; flex-direction: column; gap: 9px; }
.entry-body li {
  position: relative; padding-left: 18px;
  font-size: 14.5px; line-height: 1.65; color: var(--ink-soft);
}
body.fa .entry-body li { padding-left: 0; padding-right: 18px; line-height: 2; }
.entry-body li::before {
  content: ''; position: absolute; left: 0; top: 9px;
  width: 5px; height: 5px; border-radius: 50%;
  background: var(--accent); box-shadow: 0 0 6px var(--accent);
}
body.fa .entry-body li::before { left: auto; right: 0; }

/* ── STACK ── */
.stack-diagram { display: flex; flex-direction: column; }
.layer {
  border: 1px solid var(--line); border-radius: 14px;
  background: var(--surface); padding: 24px 28px;
  display: grid; grid-template-columns: 190px 1fr;
  gap: 24px; align-items: start;
  cursor: default;
  transition: border-color .2s, box-shadow .2s;
  transform-style: preserve-3d; will-change: transform;
}
.layer:hover {
  border-color: var(--accent-tint);
  box-shadow: 0 0 40px rgba(124,140,255,0.12), 0 8px 32px rgba(0,0,0,0.3);
}
.layer-label { display: flex; align-items: center; gap: 10px; }
.layer-index { font-family: var(--font-mono); font-size: 11px; color: var(--ink-faint); }
.layer-name { font-family: var(--font-display); font-weight: 600; font-size: 16px; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  font-family: var(--font-mono); font-size: 12.5px;
  padding: 6px 13px; border-radius: 999px;
  background: rgba(124,140,255,0.08);
  border: 1px solid rgba(124,140,255,0.22);
  color: var(--accent); white-space: nowrap;
  position: relative; overflow: hidden;
  transition: transform .15s, background .15s, border-color .15s;
}
.chip::after {
  content: ''; position: absolute;
  top: 0; left: -100%; width: 60%; height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.08), transparent);
  transition: left .5s;
}
.chip:hover { transform: translateY(-2px); background: rgba(124,140,255,0.18); border-color: rgba(124,140,255,0.45); }
.chip:hover::after { left: 160%; }

.layer-connector { display: flex; justify-content: flex-start; padding-left: 44px; height: 22px; }
body.fa .layer-connector { justify-content: flex-end; padding-left: 0; padding-right: 44px; }
.layer-connector span { width: 1px; height: 100%; background: linear-gradient(to bottom, var(--accent-tint), transparent); }

/* ── FOOTER ── */
.footer {
  margin-top: 40px; padding-top: 28px;
  border-top: 1px solid var(--line);
  display: flex; gap: 10px;
  font-family: var(--font-mono); font-size: 12px; color: var(--ink-faint);
}
body.fa .footer { font-family: var(--font-fa); }
.footer-dot { color: var(--line); }

/* ── RESPONSIVE ── */
@media (max-width: 880px) {
  .page { grid-template-columns: 1fr; }
  .sidebar { position: static; height: auto; border-right: none; border-bottom: 1px solid var(--line); padding: 36px 20px 28px; }
  body.fa .sidebar { border-left: none; border-bottom: 1px solid var(--line); }
  .index-nav { flex-direction: row; flex-wrap: wrap; gap: 8px; margin-bottom: 20px; }
  .index-nav a { border: 1px solid var(--line); border-radius: 999px; padding: 7px 13px; }
  .index-nav a:first-child { border-top: 1px solid var(--line); }
  .content { padding: 36px 20px 60px; }
  .entry { grid-template-columns: 1fr; gap: 6px; }
  .layer { grid-template-columns: 1fr; gap: 14px; }
  .layer-connector { padding-left: 24px; }
  body.fa .layer-connector { padding-right: 24px; }
  .lang-toggle { top: 12px; right: 12px; }
}

/* ── PRINT ── */
@media print {
  :root {
    --ink:#14191F; --ink-soft:#5B6470; --ink-faint:#9AA2AC;
    --paper:#fff; --surface:#fff; --line:#E4E2DC;
    --accent:#2F3FA6; --accent-glow:transparent; --accent-tint:#DADEF5;
  }
  #bg-canvas, .lang-toggle { display: none; }
  body { background: #fff; }
  .page { grid-template-columns: 220px 1fr; max-width: 100%; }
  .sidebar { position: static; height: auto; backdrop-filter: none; background: #fff; border-right: 1px solid #eee; padding: 24px 20px; }
  body.fa .sidebar { border-right: none; border-left: 1px solid #eee; }
  .print-btn { display: none; }
  .content { padding: 24px 32px 40px; }
  .section { opacity: 1 !important; transform: none !important; margin-bottom: 30px; page-break-inside: avoid; }
  .entry { page-break-inside: avoid; }
  .entry::before { display: none; }
  .layer { box-shadow: none; border: 1px solid #e0e0e0; }
  .chip { background: #f4f4f4; border-color: #ddd; color: #333; }
  .chip::after { display: none; }
  .monogram { box-shadow: none; background: #14191F; }
  .tw-cursor { display: none; }
}