/* ═══════════════════════════════════════════════════════
   shared.css — xNeog Design System Base
   Reset, dark/light vars, grain, scrollbar, animations,
   reveal, theme toggle, topnav, reading progress, responsive
   ═══════════════════════════════════════════════════════ */

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

html { scroll-behavior: smooth; }

/* ── Scrollbar ── */
::-webkit-scrollbar { width: 4px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.15); border-radius: 2px; }
[data-theme="light"] ::-webkit-scrollbar-thumb { background: rgba(0,0,0,0.15); }

/* ── Grain Texture ── */
body::after {
  content: '';
  position: fixed;
  inset: 0;
  opacity: 0.025;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 512 512' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.75' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 9999;
}

/* ── Animations ── */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(28px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes fadeDown {
  from { opacity: 0; transform: translateY(-12px); }
  to { opacity: 1; }
}
@keyframes drawLine {
  from { transform: scaleX(0); }
  to { transform: scaleX(1); }
}
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

/* ── Scroll Reveal ── */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.7s cubic-bezier(.16,1,.3,1), transform 0.7s cubic-bezier(.16,1,.3,1);
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Theme Toggle (editorial — fixed top-right circle) ── */
.theme-toggle {
  position: fixed;
  top: 24px;
  right: 24px;
  z-index: 100;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--border);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  transition: all 0.3s;
  color: var(--text-dim);
}
.theme-toggle:hover {
  border-color: var(--accent-border, var(--border));
  color: var(--accent);
  transform: scale(1.08);
}

/* ── Top Navigation ── */
.topnav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 90;
  padding: 18px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: transparent;
  transition: background 0.3s, backdrop-filter 0.3s;
}
.topnav.scrolled {
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}
.topnav-brand {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-dim);
  text-decoration: none;
  transition: color 0.2s;
}
.topnav-brand:hover { color: var(--accent); }

.topnav-links {
  display: flex;
  align-items: center;
  gap: 20px;
}
.topnav-links a {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-dim, rgba(255,255,255,0.35));
  text-decoration: none;
  transition: color 0.2s;
}
.topnav-links a:hover { color: var(--accent); }
.topnav-links a.active { color: var(--accent); }

.topnav-tag {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-faint, rgba(255,255,255,0.15));
}

/* ── Reading Progress ── */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  background: var(--accent);
  z-index: 999;
  transition: width 0.1s linear;
  box-shadow: 0 0 8px var(--accent-glow, rgba(212,168,83,0.08));
}

/* ── Responsive Base ── */
@media (max-width: 600px) {
  .topnav { padding: 16px 20px; }
  .topnav-links { gap: 12px; }
  .topnav-links a { font-size: 9px; }
}