/* ============================================================
   Additional landing-page sections (v2 rebuild)
   - Who is MUXA (multiplexer story)
   - Field notes (writing / POV)
   - Mobile nav overlay
   - Scroll-driven entrance animations
   - Focus-visible polish
   ============================================================ */

/* ---------- Who is MUXA / multiplexer story ---------- */
.who {
  background: var(--surface-secondary);
  padding: 120px 0;
  border-bottom: 1px solid var(--surface-border);
}
.who-grid {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 80px;
  align-items: center;
}
@media (max-width: 1000px) {
  .who { padding: 80px 0; }
  .who-grid { grid-template-columns: 1fr; gap: 48px; }
}
.who-text .kicker {
  margin-bottom: 24px;
  display: block;
}
.who-text h2 {
  font-family: var(--font-serif);
  font-weight: 500;
  font-size: clamp(40px, 5.6vw, 84px);
  line-height: 1.02;
  letter-spacing: var(--ls-tight);
  margin: 0;
}
.who-text p {
  margin: 32px 0 0;
  font-size: var(--fs-body-lg);
  line-height: 1.55;
  color: var(--text-secondary);
  max-width: 540px;
}
.who-text p strong {
  color: var(--text-primary);
  font-weight: 500;
}

/* The multiplexer diagram: inputs converge, one output comes out */
.mux {
  position: relative;
  aspect-ratio: 1 / 1;
  max-width: 480px;
  margin: 0 auto;
}
.mux-svg {
  width: 100%;
  height: 100%;
  overflow: visible;
}
.mux-svg .axis    { stroke: var(--surface-border); stroke-width: 1; }
.mux-svg .input   {
  stroke: var(--color-slate);
  stroke-width: 1.5;
  fill: none;
  stroke-dasharray: 200;
  stroke-dashoffset: 200;
  animation: mux-draw 4s var(--ease-out) infinite;
}
.mux-svg .input:nth-child(1) { animation-delay: 0.0s; }
.mux-svg .input:nth-child(2) { animation-delay: 0.3s; }
.mux-svg .input:nth-child(3) { animation-delay: 0.6s; }
.mux-svg .input:nth-child(4) { animation-delay: 0.9s; }
.mux-svg .input.teal { stroke: var(--color-teal); }
.mux-svg .input.red  { stroke: var(--color-red);  }
.mux-svg .output {
  stroke: var(--fill-brand);
  stroke-width: 2.5;
  fill: none;
}
.mux-svg .node-bg {
  fill: var(--surface-primary);
  stroke: var(--text-primary);
  stroke-width: 1.5;
}
.mux-svg .node-letter {
  font-family: var(--font-serif);
  font-weight: 500;
  font-size: 26px;
  fill: var(--text-primary);
  text-anchor: middle;
  dominant-baseline: central;
}
.mux-svg .label {
  font-family: var(--font-mono);
  font-size: 9.5px;
  fill: var(--text-secondary);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.mux-svg .label.r { text-anchor: end; }
.mux-svg .endpoint {
  fill: var(--fill-brand);
}
.mux-svg .input-dot {
  fill: var(--color-slate);
  opacity: 0;
  animation: mux-dot 4s var(--ease-out) infinite;
}
.mux-svg .input-dot.teal { fill: var(--color-teal); }
.mux-svg .input-dot.red  { fill: var(--color-red); }
.mux-svg .input-dot:nth-of-type(1) { animation-delay: 0.0s; }
.mux-svg .input-dot:nth-of-type(2) { animation-delay: 0.3s; }
.mux-svg .input-dot:nth-of-type(3) { animation-delay: 0.6s; }
.mux-svg .input-dot:nth-of-type(4) { animation-delay: 0.9s; }
.mux-svg .output-pulse {
  fill: var(--fill-brand);
  opacity: 0;
  animation: mux-out 4s var(--ease-out) infinite;
  animation-delay: 1.6s;
}

@keyframes mux-draw {
  0%   { stroke-dashoffset: 200; }
  35%  { stroke-dashoffset: 0;   }
  85%  { stroke-dashoffset: 0;   opacity: 1; }
  100% { stroke-dashoffset: 0;   opacity: 0.2; }
}
@keyframes mux-dot {
  0%, 5%   { opacity: 0; }
  20%      { opacity: 1; }
  85%      { opacity: 1; }
  100%     { opacity: 0; }
}
@keyframes mux-out {
  0%, 10%  { opacity: 0; transform: scale(0.6); }
  30%      { opacity: 1; transform: scale(1);   }
  70%      { opacity: 1; transform: scale(1.4); }
  100%     { opacity: 0; transform: scale(1.6); }
}

@media (prefers-reduced-motion: reduce) {
  .mux-svg .input { animation: none; stroke-dashoffset: 0; }
  .mux-svg .input-dot,
  .mux-svg .output-pulse { animation: none; opacity: 1; }
}

/* ---------- Field notes (writing) ---------- */
.notes {
  padding: 120px 0;
  border-bottom: 1px solid var(--surface-border);
}
.notes-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 24px;
}
@media (max-width: 1000px) {
  .notes-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 680px) {
  .notes-grid { grid-template-columns: 1fr; }
}
.note {
  display: flex;
  flex-direction: column;
  padding: 36px 28px 28px;
  background: var(--surface-secondary);
  border: 1px solid var(--surface-border);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  color: var(--text-primary);
  min-height: 320px;
}
.note:hover {
  transform: translateY(-3px);
  box-shadow: 0 24px 48px -28px rgba(20, 20, 20, 0.2);
}
.note-meta {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: var(--ls-kicker);
  text-transform: uppercase;
  color: var(--text-secondary);
  margin-bottom: 28px;
  gap: 12px;
}
.note h3 {
  font-family: 'General Sans', var(--font-sans), sans-serif;
  font-weight: 600;
  font-size: clamp(18px, 1.5vw, 22px);
  line-height: 1.3;
  letter-spacing: -0.005em;
  margin: 0 0 16px;
  color: var(--text-primary);
}
.note p {
  margin: 0 0 24px;
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.5;
}
.note .read {
  margin-top: auto;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-primary);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  align-self: flex-start;
  padding-bottom: 4px;
  background-image: linear-gradient(var(--accent-voltage), var(--accent-voltage));
  background-repeat: no-repeat;
  background-position: 0 100%;
  background-size: 0 2px;
  transition: background-size 0.35s var(--ease-out);
}
.note:hover .read { background-size: 100% 2px; }
.note .read.pending { color: var(--text-secondary); }

/* ---------- Mobile nav overlay ---------- */
.menu-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--surface-border);
  border-radius: var(--r-pill);
  color: var(--text-primary);
  cursor: pointer;
}
.menu-toggle svg { width: 18px; height: 18px; }

@media (max-width: 880px) {
  .menu-toggle { display: inline-flex; }
}

.mobile-menu {
  position: fixed;
  inset: 0;
  background: var(--surface-primary);
  z-index: 60;
  display: flex;
  flex-direction: column;
  padding: 24px;
  transform: translateY(-100%);
  transition: transform 0.35s var(--ease-out);
  visibility: hidden;
}
.mobile-menu[aria-hidden="false"] {
  transform: translateY(0);
  visibility: visible;
}
.mobile-menu-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 6px 0 0;
}
.mobile-menu-nav {
  display: flex;
  flex-direction: column;
  gap: 24px;
  margin-top: 64px;
}
.mobile-menu-nav a {
  font-family: var(--font-serif);
  font-weight: 500;
  font-size: 40px;
  line-height: 1;
  letter-spacing: var(--ls-tight);
  color: var(--text-primary);
  padding: 12px 0;
  border-bottom: 1px solid var(--surface-border);
}
.mobile-menu-foot {
  margin-top: auto;
  padding-top: 32px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: var(--ls-kicker);
  text-transform: uppercase;
  color: var(--text-secondary);
}
.mobile-menu-foot a { color: var(--text-primary); }

body.menu-open {
  overflow: hidden;
}

/* ---------- Scroll-driven entrance ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
}
.reveal.in {
  opacity: 1;
  transform: translateY(0);
}
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* ---------- Focus-visible polish ---------- */
:focus-visible {
  outline: 2px solid var(--fill-brand);
  outline-offset: 3px;
  border-radius: 2px;
}
.pill:focus-visible,
.theme-toggle:focus-visible,
.menu-toggle:focus-visible {
  outline-offset: 2px;
}
.step:focus-visible .ring {
  outline: 2px solid var(--color-sodium);
  outline-offset: 4px;
}

/* ---------- Refined section-head: tweak max-widths ---------- */
.section-head p { max-width: 580px; }