/* ============================== RESET & TOKENS ============================== */
:root {
  --bg: #0a0b14;
  --bg-2: #10121f;
  --panel: #161a2c;
  --panel-2: #1d2238;
  --line: #2a3050;
  --text: #e8ebf5;
  --muted: #9aa3c4;
  --dim: #6b7299;

  --accent: #7c5cff;
  --accent-2: #21d4fd;
  --grad: linear-gradient(120deg, #7c5cff 0%, #21d4fd 100%);

  --fetch: #ffb020;
  --decode: #21d4fd;
  --execute: #34e89e;
  --danger: #ff5c7c;
  --ok: #34e89e;

  --radius: 16px;
  --radius-sm: 10px;
  --mono: "JetBrains Mono", ui-monospace, monospace;
  --sans: "Inter", system-ui, sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

::selection { background: rgba(124, 92, 255, 0.4); }

code, kbd, .mono { font-family: var(--mono); }

code {
  background: rgba(124, 92, 255, 0.14);
  color: #c5b8ff;
  padding: 1px 6px;
  border-radius: 6px;
  font-size: 0.88em;
}

kbd {
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-bottom-width: 2px;
  border-radius: 6px;
  padding: 1px 7px;
  font-size: 0.82em;
}

/* ============================== SCROLL PROGRESS ============================== */
#scroll-progress {
  position: fixed;
  top: 0; left: 0;
  height: 3px;
  width: 0%;
  background: var(--grad);
  z-index: 100;
  box-shadow: 0 0 12px rgba(124, 92, 255, 0.6);
}

/* ============================== SIDE NAV ============================== */
#sidenav {
  position: fixed;
  top: 0; left: 0;
  width: 230px;
  height: 100vh;
  padding: 28px 18px;
  background: rgba(13, 15, 26, 0.7);
  backdrop-filter: blur(14px);
  border-right: 1px solid var(--line);
  z-index: 90;
  display: flex;
  flex-direction: column;
  gap: 4px;
  overflow-y: auto;
}

.nav-brand {
  font-weight: 800;
  font-size: 1.2rem;
  margin-bottom: 18px;
  letter-spacing: -0.02em;
}
.nav-brand span { color: var(--dim); font-weight: 500; }

.nav-link {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.86rem;
  font-weight: 500;
  padding: 7px 12px;
  border-radius: 8px;
  border-left: 2px solid transparent;
  transition: all 0.15s ease;
}
.nav-link:hover { color: var(--text); background: rgba(124, 92, 255, 0.08); }
.nav-link.active {
  color: var(--text);
  background: rgba(124, 92, 255, 0.14);
  border-left-color: var(--accent);
}

#nav-toggle {
  display: none;
  position: fixed;
  top: 14px; left: 14px;
  z-index: 95;
  background: var(--panel);
  border: 1px solid var(--line);
  color: var(--text);
  width: 42px; height: 42px;
  border-radius: 10px;
  font-size: 1.2rem;
  cursor: pointer;
}

/* ============================== LAYOUT ============================== */
main { margin-left: 230px; }

.section {
  max-width: 980px;
  margin: 0 auto;
  padding: 90px 32px;
  border-bottom: 1px solid rgba(42, 48, 80, 0.5);
}

.section-head { margin-bottom: 40px; }

.kicker {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-2);
  margin-bottom: 12px;
}

h2 {
  font-size: clamp(1.7rem, 3.4vw, 2.6rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.15;
  margin-bottom: 18px;
}
h2 em { font-style: normal; color: var(--accent); }

.explain {
  color: var(--muted);
  font-size: 1.05rem;
  max-width: 760px;
  margin-bottom: 14px;
}
.explain.center { margin-left: auto; margin-right: auto; text-align: center; }
.explain strong { color: var(--text); }

.caption {
  color: var(--dim);
  font-size: 0.9rem;
  margin-top: 22px;
  max-width: 800px;
}

.panel-title {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--dim);
  margin-bottom: 12px;
}

/* ============================== HERO ============================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  padding: 40px;
  overflow: hidden;
}
.hero-inner { max-width: 760px; text-align: center; position: relative; z-index: 2; }

.badge {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent-2);
  border: 1px solid var(--line);
  background: rgba(33, 212, 253, 0.06);
  padding: 6px 14px;
  border-radius: 100px;
  margin-bottom: 28px;
}

.hero h1 {
  font-size: clamp(3rem, 9vw, 6rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 0.95;
  margin-bottom: 28px;
}
.grad {
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.lede { font-size: 1.2rem; color: var(--muted); margin-bottom: 16px; }
.lede strong { color: var(--text); }
.lede em { color: var(--accent-2); font-style: normal; }
.sub { color: var(--dim); margin-bottom: 36px; }

.cta {
  display: inline-block;
  background: var(--grad);
  color: #0a0b14;
  font-weight: 700;
  text-decoration: none;
  padding: 14px 32px;
  border-radius: 100px;
  font-size: 1.05rem;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
  box-shadow: 0 8px 30px rgba(124, 92, 255, 0.35);
}
.cta:hover { transform: translateY(-2px); box-shadow: 0 12px 40px rgba(124, 92, 255, 0.5); }

.hero-glow {
  position: absolute;
  width: 700px; height: 700px;
  background: radial-gradient(circle, rgba(124, 92, 255, 0.22), transparent 60%);
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  filter: blur(40px);
  z-index: 1;
  animation: pulse 6s ease-in-out infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 0.6; transform: translate(-50%, -50%) scale(1); }
  50% { opacity: 1; transform: translate(-50%, -50%) scale(1.1); }
}

/* ============================== LAYER STACK ============================== */
.layer-stack { display: flex; flex-direction: column; gap: 2px; margin: 10px 0; }
.layer {
  border-radius: var(--radius);
  padding: 24px 28px;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.2s ease, filter 0.2s ease;
  display: flex;
  flex-direction: column;
  gap: 4px;
  border: 1px solid transparent;
}
.layer:hover { transform: scale(1.015); }
.layer-title { font-weight: 700; font-size: 1.1rem; }
.layer-sub { color: rgba(255,255,255,0.6); font-size: 0.9rem; }
.layer-app { background: linear-gradient(135deg, rgba(33,212,253,0.16), rgba(33,212,253,0.05)); border-color: rgba(33,212,253,0.3); }
.layer-os { background: linear-gradient(135deg, rgba(124,92,255,0.22), rgba(124,92,255,0.07)); border-color: rgba(124,92,255,0.4); }
.layer-hw { background: linear-gradient(135deg, rgba(52,232,158,0.14), rgba(52,232,158,0.04)); border-color: rgba(52,232,158,0.3); }
.layer-arrow { text-align: center; color: var(--dim); font-size: 0.8rem; padding: 6px 0; }
.tag {
  font-size: 0.7rem; font-weight: 700; background: var(--accent); color: #0a0b14;
  padding: 2px 8px; border-radius: 100px; vertical-align: middle;
}

/* three pillars */
.three-pillars { margin-top: 56px; }
.pillar-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 24px; }
.pillar {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 26px 22px;
  text-decoration: none;
  color: var(--text);
  transition: transform 0.15s ease, border-color 0.15s ease, background 0.15s ease;
}
.pillar:hover { transform: translateY(-4px); border-color: var(--accent); background: var(--panel-2); }
.pillar-icon { font-size: 2rem; margin-bottom: 12px; }
.pillar h3 { font-size: 1.15rem; margin-bottom: 8px; }
.pillar p { color: var(--muted); font-size: 0.92rem; }
.pillar em { color: var(--accent-2); font-style: normal; }

/* ============================== GENERIC CONTROLS ============================== */
.controls { display: flex; gap: 10px; flex-wrap: wrap; }
.controls.vertical { flex-direction: column; align-items: stretch; }

.btn {
  background: var(--panel-2);
  color: var(--text);
  border: 1px solid var(--line);
  padding: 10px 18px;
  border-radius: 10px;
  font-family: var(--sans);
  font-weight: 600;
  font-size: 0.92rem;
  cursor: pointer;
  transition: all 0.13s ease;
}
.btn:hover { border-color: var(--accent); background: #232a44; }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn-primary { background: var(--grad); color: #0a0b14; border: none; }
.btn-primary:hover { filter: brightness(1.08); }
.btn-ghost { background: transparent; }
.btn-danger { background: rgba(255,92,124,0.16); border-color: rgba(255,92,124,0.5); color: #ff9db1; }
.btn-danger:hover { background: rgba(255,92,124,0.28); }

.screen {
  background: #05060d;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 16px;
  font-family: var(--mono);
  font-size: 0.95rem;
  min-height: 80px;
  color: var(--ok);
  white-space: pre-wrap;
  word-break: break-word;
}

.hint { color: var(--dim); font-size: 0.85rem; margin-top: 10px; }

/* ============================== CPU / FDE DEMO ============================== */
.cpu-demo {
  display: grid;
  grid-template-columns: 1fr 1.2fr 1fr;
  gap: 16px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
}
.cpu-memory, .cpu-core, .cpu-output { min-width: 0; }

.instr-list { list-style: none; counter-reset: line; }
.instr-list li {
  font-family: var(--mono);
  font-size: 0.88rem;
  padding: 7px 12px;
  border-radius: 8px;
  margin-bottom: 4px;
  border: 1px solid transparent;
  color: var(--muted);
  display: flex;
  gap: 10px;
  transition: all 0.15s ease;
}
.instr-list li .ln { color: var(--dim); width: 18px; }
.instr-list li.active {
  background: rgba(124,92,255,0.18);
  border-color: var(--accent);
  color: var(--text);
}

.stage-track { display: flex; gap: 6px; margin-bottom: 14px; }
.stage {
  flex: 1;
  text-align: center;
  padding: 10px 4px;
  border-radius: 8px;
  border: 1px solid var(--line);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--dim);
  transition: all 0.2s ease;
}
.stage[data-stage="fetch"].on { background: rgba(255,176,32,0.2); border-color: var(--fetch); color: var(--fetch); }
.stage[data-stage="decode"].on { background: rgba(33,212,253,0.2); border-color: var(--decode); color: var(--decode); }
.stage[data-stage="execute"].on { background: rgba(52,232,158,0.2); border-color: var(--execute); color: var(--execute); }

.cpu-readout {
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 12px;
  font-size: 0.85rem;
  color: var(--muted);
  min-height: 64px;
  margin-bottom: 14px;
}

.registers { display: flex; gap: 10px; margin-bottom: 16px; }
.reg {
  flex: 1;
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 10px;
  text-align: center;
}
.reg-name { display: block; font-family: var(--mono); font-size: 0.75rem; color: var(--accent-2); }
.reg-val { display: block; font-family: var(--mono); font-size: 1.5rem; font-weight: 700; }
.reg-note { display: block; font-size: 0.68rem; color: var(--dim); }

.step-legend { list-style: none; margin-top: 18px; display: flex; flex-direction: column; gap: 6px; }
.step-legend li { color: var(--muted); font-size: 0.92rem; display: flex; align-items: center; gap: 10px; }
.dot { width: 11px; height: 11px; border-radius: 50%; display: inline-block; }
.dot.fetch { background: var(--fetch); }
.dot.decode { background: var(--decode); }
.dot.execute { background: var(--execute); }

/* ============================== SCHEDULER DEMO ============================== */
.sched-demo {
  display: grid;
  grid-template-columns: 1fr 1.3fr;
  gap: 18px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
}
.proc-pool { display: flex; flex-direction: column; gap: 8px; margin-bottom: 18px; }
.proc-item {
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 10px 14px;
  transition: all 0.15s ease;
}
.proc-item.active {
  border-color: var(--accent);
  background: rgba(124,92,255,0.12);
  box-shadow: 0 0 0 2px rgba(124,92,255,0.25);
}
.proc-badge {
  width: 34px; height: 34px;
  border-radius: 8px;
  display: grid; place-items: center;
  font-weight: 800;
  font-family: var(--mono);
  color: #0a0b14;
}
.proc-meta { font-size: 0.82rem; color: var(--muted); }
.proc-meta .pid { color: var(--dim); font-family: var(--mono); }
.proc-bar { height: 5px; border-radius: 3px; background: var(--line); margin-top: 4px; overflow: hidden; }
.proc-bar i { display: block; height: 100%; width: 0%; transition: width 0.1s linear; }

.slider-row { display: flex; flex-direction: column; gap: 6px; font-size: 0.85rem; color: var(--muted); }
.slider-row span { color: var(--accent-2); font-weight: 700; font-family: var(--mono); }
input[type="range"] { width: 100%; accent-color: var(--accent); }

.cpu-chip {
  height: 120px;
  border-radius: var(--radius);
  border: 2px dashed var(--line);
  display: grid;
  place-items: center;
  font-family: var(--mono);
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--dim);
  background: radial-gradient(circle, rgba(124,92,255,0.06), transparent);
  transition: all 0.1s ease;
}
.cpu-chip.busy { border-style: solid; }
.sched-screen { min-height: 120px; font-size: 1.05rem; letter-spacing: 2px; line-height: 1.8; }

/* ============================== RACE DEMO ============================== */
.race-demo {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 26px;
}
.race-controls { display: flex; flex-direction: column; gap: 16px; align-items: center; text-align: center; margin-bottom: 28px; }
.goal { color: var(--muted); font-size: 0.95rem; }
.goal strong { color: var(--text); }

.toggle { display: inline-flex; align-items: center; gap: 12px; cursor: pointer; font-weight: 600; font-size: 0.92rem; }
.toggle input { display: none; }
.toggle-track {
  width: 50px; height: 28px; border-radius: 100px;
  background: var(--panel-2); border: 1px solid var(--line);
  position: relative; transition: background 0.2s ease;
}
.toggle-thumb {
  position: absolute; top: 2px; left: 2px;
  width: 22px; height: 22px; border-radius: 50%;
  background: var(--dim); transition: all 0.2s ease;
}
.toggle input:checked + .toggle-track { background: rgba(52,232,158,0.3); border-color: var(--ok); }
.toggle input:checked + .toggle-track .toggle-thumb { left: 24px; background: var(--ok); }

.race-stage { display: grid; grid-template-columns: 1fr auto 1fr; gap: 18px; align-items: center; }
.thread-col {
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  transition: all 0.15s ease;
}
.thread-col.active-a { border-color: var(--accent-2); box-shadow: 0 0 0 2px rgba(33,212,253,0.25); }
.thread-col.active-b { border-color: var(--accent); box-shadow: 0 0 0 2px rgba(124,92,255,0.25); }
.thread-title { font-weight: 700; margin-bottom: 12px; }
.thread-op { font-family: var(--mono); font-size: 0.9rem; color: var(--accent-2); min-height: 24px; }

.counter-box {
  background: #05060d;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 30px;
  text-align: center;
}
.counter-label { font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--dim); }
.counter-val { font-family: var(--mono); font-size: 3rem; font-weight: 800; }
.counter-status { font-size: 0.85rem; font-weight: 700; min-height: 20px; }
.counter-status.ok { color: var(--ok); }
.counter-status.bad { color: var(--danger); }

/* ============================== PERSISTENCE DEMO ============================== */
.persist-demo {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 20px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
}
.store-col { display: flex; flex-direction: column; gap: 16px; }
.store { border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; min-height: 150px; }
.store.ram { background: linear-gradient(135deg, rgba(33,212,253,0.08), transparent); }
.store.disk { background: linear-gradient(135deg, rgba(52,232,158,0.08), transparent); }
.store-head { font-weight: 700; margin-bottom: 12px; display: flex; align-items: center; gap: 10px; }
.store-tag { font-size: 0.68rem; padding: 2px 8px; border-radius: 100px; font-weight: 700; text-transform: uppercase; }
.store-tag.volatile { background: rgba(255,176,32,0.2); color: var(--fetch); }
.store-tag.durable { background: rgba(52,232,158,0.2); color: var(--ok); }
.store-body { display: flex; flex-wrap: wrap; gap: 8px; }
.data-chip {
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 6px 12px;
  font-family: var(--mono);
  font-size: 0.82rem;
  animation: pop 0.25s ease;
}
.data-chip.saved { border-color: var(--ok); color: #9ef5cf; }
@keyframes pop { from { transform: scale(0.7); opacity: 0; } to { transform: scale(1); opacity: 1; } }
.persist-controls { display: flex; flex-direction: column; gap: 10px; }
.text-input {
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 11px 14px;
  color: var(--text);
  font-family: var(--mono);
  font-size: 0.9rem;
}
.text-input:focus { outline: none; border-color: var(--accent); }

.flash-off { animation: flashoff 0.6s ease; }
@keyframes flashoff { 0% { filter: brightness(3); } 100% { filter: brightness(1); } }

/* ============================== TRAP DEMO ============================== */
.trap-demo { display: grid; grid-template-columns: 1.3fr 1fr; gap: 20px; background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; }
.mode-rail { display: flex; flex-direction: column; gap: 0; border-radius: var(--radius); overflow: hidden; position: relative; }
.mode-zone { padding: 24px; min-height: 150px; position: relative; }
.user-zone { background: linear-gradient(135deg, rgba(33,212,253,0.1), transparent); border: 1px solid rgba(33,212,253,0.3); border-radius: var(--radius) var(--radius) 0 0; }
.kernel-zone { background: linear-gradient(135deg, rgba(255,92,124,0.1), transparent); border: 1px solid rgba(255,92,124,0.3); border-top: none; border-radius: 0 0 var(--radius) var(--radius); }
.zone-label { font-weight: 800; font-size: 0.82rem; letter-spacing: 0.06em; color: var(--muted); }
.perm { font-weight: 600; font-size: 0.72rem; color: var(--accent-2); margin-left: 8px; }
.perm-full { color: var(--danger); }
.prog-dot {
  margin-top: 24px;
  width: max-content;
  background: var(--grad);
  color: #0a0b14;
  font-weight: 700;
  padding: 10px 18px;
  border-radius: 100px;
  font-size: 0.9rem;
  transition: transform 0.5s cubic-bezier(0.5,0,0.2,1);
}
.prog-dot.in-kernel { transform: translateY(165px); }
.trap-side { display: flex; flex-direction: column; gap: 12px; }
.trap-log {
  background: #05060d;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 14px;
  font-family: var(--mono);
  font-size: 0.82rem;
  min-height: 160px;
  flex: 1;
  color: var(--muted);
  overflow-y: auto;
}
.trap-log .tl { margin-bottom: 4px; }
.trap-log .tl.k { color: #ff9db1; }
.trap-log .tl.u { color: var(--accent-2); }

/* ============================== PROCESS DEMO ============================== */
.process-demo { display: grid; grid-template-columns: 1fr 1.1fr; gap: 20px; }
.addr-space, .reg-space { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; }
.mem-region {
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 16px;
  margin-bottom: 6px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all 0.15s ease;
}
.mem-region:hover { border-color: var(--accent); background: var(--panel-2); transform: translateX(4px); }
.mem-region span { font-weight: 700; }
.mem-region small { color: var(--dim); font-size: 0.78rem; }
.mem-region.heap { background: linear-gradient(135deg, rgba(124,92,255,0.1), var(--bg-2)); }
.mem-region.stack { background: linear-gradient(135deg, rgba(33,212,253,0.1), var(--bg-2)); }
.mem-gap { text-align: center; color: var(--dim); padding: 6px; font-size: 0.78rem; }

.reg-card {
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 16px;
  margin-bottom: 8px;
  cursor: pointer;
  transition: all 0.15s ease;
}
.reg-card:hover { border-color: var(--accent-2); background: var(--panel-2); }
.rc-name { font-family: var(--mono); font-weight: 700; color: var(--accent-2); margin-right: 12px; }
.rc-desc { color: var(--muted); font-size: 0.88rem; }
.callout {
  background: rgba(124,92,255,0.1);
  border: 1px solid rgba(124,92,255,0.3);
  border-radius: 10px;
  padding: 16px;
  margin-top: 14px;
  font-size: 0.9rem;
  color: var(--muted);
}
.callout strong { color: var(--text); }
.callout a { color: var(--accent-2); display: block; margin-top: 8px; }

/* tooltip (shared) */
#tooltip {
  position: fixed;
  z-index: 200;
  max-width: 280px;
  background: var(--panel-2);
  border: 1px solid var(--accent);
  border-radius: 10px;
  padding: 12px 14px;
  font-size: 0.85rem;
  color: var(--text);
  box-shadow: 0 12px 40px rgba(0,0,0,0.5);
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.12s ease;
}
#tooltip.show { opacity: 1; }
#tooltip .tt-name { font-weight: 700; color: var(--accent-2); display: block; margin-bottom: 4px; font-family: var(--mono); font-size: 0.8rem; }

/* ============================== STATES DEMO ============================== */
.states-demo { display: grid; grid-template-columns: 1.2fr 1fr; gap: 20px; }
.state-map { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; display: flex; flex-direction: column; gap: 12px; justify-content: center; }
.state-node {
  border: 2px solid var(--line);
  border-radius: 12px;
  padding: 16px;
  text-align: center;
  font-weight: 800;
  letter-spacing: 0.04em;
  color: var(--dim);
  transition: all 0.25s ease;
}
.state-node small { display: block; font-weight: 500; font-size: 0.74rem; letter-spacing: 0; color: var(--dim); margin-top: 3px; }
.state-node.active {
  border-color: var(--accent);
  background: rgba(124,92,255,0.18);
  color: var(--text);
  box-shadow: 0 0 24px rgba(124,92,255,0.3);
  transform: scale(1.03);
}
.state-node.active small { color: var(--muted); }

.state-controls { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; }
.cur-state { color: var(--accent); font-family: var(--mono); text-transform: uppercase; }
.transition-buttons { display: flex; flex-direction: column; gap: 8px; }
.state-log {
  background: #05060d;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 12px;
  font-family: var(--mono);
  font-size: 0.8rem;
  min-height: 100px;
  max-height: 180px;
  overflow-y: auto;
  color: var(--muted);
}

/* ============================== STRUCT DEMO ============================== */
.struct-demo { display: grid; grid-template-columns: 1.1fr 1fr; gap: 20px; }
.struct-code {
  background: #05060d;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  font-family: var(--mono);
  font-size: 0.86rem;
  line-height: 1.8;
  overflow-x: auto;
  color: var(--muted);
}
.struct-code .kw { color: #c792ea; }
.struct-code .ty { color: #82aaff; }
.struct-code .cm { color: var(--dim); font-style: italic; }
.field {
  cursor: pointer;
  border-radius: 5px;
  padding: 0 3px;
  transition: all 0.13s ease;
  border-bottom: 1px dashed rgba(124,92,255,0.5);
}
.field:hover { background: rgba(124,92,255,0.2); color: var(--text); }
.field.selected { background: var(--accent); color: #0a0b14; border-bottom-color: transparent; }

.struct-info { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 24px; }
.si-placeholder { color: var(--dim); }
.si-field { font-family: var(--mono); font-size: 1.1rem; font-weight: 700; color: var(--accent-2); margin-bottom: 6px; }
.si-maps { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--accent); font-weight: 700; margin-bottom: 12px; }
.si-text { color: var(--muted); font-size: 0.95rem; }
.si-link { display: inline-block; margin-top: 14px; color: var(--accent-2); text-decoration: none; font-size: 0.88rem; }
.si-link:hover { text-decoration: underline; }

/* ============================== FINALE / FOOTER ============================== */
.finale { text-align: center; margin-top: 64px; background: linear-gradient(135deg, rgba(124,92,255,0.12), rgba(33,212,253,0.06)); border: 1px solid var(--line); border-radius: var(--radius); padding: 48px 32px; }
.finale h3 { font-size: 2rem; margin-bottom: 16px; }
.finale p { color: var(--muted); max-width: 680px; margin: 0 auto 28px; }
.footer { text-align: center; padding: 50px 32px; color: var(--dim); font-size: 0.85rem; }

/* ============================== FORK / EXEC DEMO ============================== */
.fe-demo { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.fe-stage { display: flex; flex-direction: column; gap: 16px; }
.fe-proc {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px 20px;
  transition: all 0.25s ease;
}
.fe-proc.empty { border-style: dashed; opacity: 0.55; }
.fe-proc.spawn { animation: pop 0.35s ease; }
.fe-proc.is-running { border-color: var(--ok); box-shadow: 0 0 0 2px rgba(52,232,158,0.25); }
.fe-proc.is-blocked { border-color: var(--fetch); box-shadow: 0 0 0 2px rgba(255,176,32,0.2); }
.fe-proc.is-zombie { border-color: var(--danger); opacity: 0.8; }
.fe-proc.exec-flash { animation: execflash 0.6s ease; }
@keyframes execflash { 0% { background: rgba(124,92,255,0.35); } 100% { background: var(--panel); } }
.fe-head { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 10px; }
.fe-name { font-weight: 800; font-size: 1.1rem; }
.fe-pid { font-family: var(--mono); font-size: 0.82rem; color: var(--dim); }
.fe-state { font-family: var(--mono); font-size: 0.82rem; font-weight: 700; color: var(--muted); margin-bottom: 6px; }
.fe-prog { font-size: 0.9rem; color: var(--muted); }
.fe-prog b { color: var(--accent-2); font-family: var(--mono); }
.fe-ret { font-family: var(--mono); font-size: 0.8rem; color: var(--ok); margin-top: 8px; min-height: 18px; }
.fe-side { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; display: flex; flex-direction: column; }
.fe-explain { background: var(--bg-2); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 14px; font-size: 0.9rem; color: var(--muted); min-height: 80px; }
.fe-explain code { font-size: 0.85em; }
.fe-term { min-height: 90px; font-size: 0.9rem; }
.fe-progress { display: flex; gap: 6px; margin-top: 14px; flex-wrap: wrap; }
.fe-progress .dot-step { width: 9px; height: 9px; border-radius: 50%; background: var(--line); transition: all 0.2s ease; }
.fe-progress .dot-step.done { background: var(--accent); }

/* ============================== CONTEXT SWITCH DEMO ============================== */
.cs-demo { display: grid; grid-template-columns: 1fr 1.1fr 1fr; gap: 16px; align-items: start; }
.cs-proc, .cs-cpu { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; transition: all 0.25s ease; }
.cs-cpu { background: radial-gradient(circle at 50% 0%, rgba(124,92,255,0.12), var(--panel)); border-color: rgba(124,92,255,0.4); }
.cs-title { font-weight: 800; margin-bottom: 14px; display: flex; align-items: center; gap: 10px; font-size: 0.98rem; }
.cs-badge { font-size: 0.66rem; font-weight: 800; text-transform: uppercase; letter-spacing: 0.05em; padding: 3px 9px; border-radius: 100px; background: rgba(52,232,158,0.2); color: var(--ok); }
.cs-badge.dim { background: var(--panel-2); color: var(--dim); }
.cs-badge.live { background: rgba(124,92,255,0.25); color: #c5b8ff; }
.cs-regs { display: flex; flex-direction: column; gap: 7px; }
.cs-reg { display: flex; justify-content: space-between; align-items: center; background: var(--bg-2); border: 1px solid var(--line); border-radius: 8px; padding: 8px 12px; font-family: var(--mono); font-size: 0.85rem; transition: all 0.3s ease; }
.cs-reg .rn { color: var(--accent-2); }
.cs-reg .rv { font-weight: 700; }
.cs-regs.cpu .cs-reg { border-color: rgba(124,92,255,0.35); }
.cs-reg.flash-save { background: rgba(255,176,32,0.25); border-color: var(--fetch); }
.cs-reg.flash-load { background: rgba(52,232,158,0.25); border-color: var(--ok); }
.cs-now { text-align: center; margin-top: 14px; font-size: 0.85rem; color: var(--muted); }
.cs-now strong { color: var(--accent); font-family: var(--mono); font-size: 1.1rem; }
.cs-proc.dim-proc { opacity: 0.5; }
.cs-controls { display: flex; justify-content: space-between; align-items: center; gap: 16px; margin-top: 18px; flex-wrap: wrap; }
.cs-log { flex: 1; min-width: 240px; background: #05060d; border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 12px 14px; font-family: var(--mono); font-size: 0.8rem; min-height: 56px; color: var(--muted); }
.cs-log .csl-s { color: var(--fetch); }
.cs-log .csl-l { color: var(--ok); }

/* ============================== ABOUT xv6 PANEL ============================== */
.xv6-about {
  background: linear-gradient(135deg, rgba(33,212,253,0.07), rgba(124,92,255,0.05));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 26px;
  margin-bottom: 22px;
}
.xa-title { font-size: 1.25rem; margin-bottom: 18px; }
.xa-title em { font-style: normal; color: var(--accent); }
.xa-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.xa-card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 18px; }
.xa-h { font-weight: 700; color: var(--accent-2); font-size: 0.92rem; margin-bottom: 8px; }
.xa-card p { color: var(--muted); font-size: 0.9rem; }
.xa-card a { color: var(--accent-2); text-decoration: none; }
.xa-card a:hover { text-decoration: underline; }
.xa-foot { margin-top: 16px; color: var(--muted); font-size: 0.9rem; text-align: center; }
.xa-foot strong { color: var(--text); }

/* ============================== THE REAL DEAL (source explorer) ============================== */
.rd { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.rd-tabs { display: flex; flex-wrap: wrap; gap: 4px; padding: 12px 12px 0; border-bottom: 1px solid var(--line); background: var(--bg-2); }
.rd-tab {
  background: transparent;
  border: 1px solid transparent;
  border-bottom: none;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 9px 14px;
  border-radius: 9px 9px 0 0;
  cursor: pointer;
  transition: all 0.13s ease;
  white-space: nowrap;
}
.rd-tab:hover { color: var(--text); background: rgba(124,92,255,0.08); }
.rd-tab.active { color: var(--text); background: var(--panel); border-color: var(--line); position: relative; top: 1px; }
.rd-tab .tab-file { color: var(--accent-2); }

.rd-panel { padding: 0; }
.rd-meta { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 18px; padding: 16px 22px; border-bottom: 1px solid var(--line); background: rgba(124,92,255,0.05); }
.rd-meta .rd-file { font-family: var(--mono); font-weight: 700; color: var(--text); font-size: 0.95rem; }
.rd-meta .rd-link { font-size: 0.8rem; color: var(--accent-2); text-decoration: none; font-weight: 600; }
.rd-meta .rd-link:hover { text-decoration: underline; }
.rd-meta .rd-note { flex-basis: 100%; color: var(--muted); font-size: 0.88rem; }
.rd-meta .rd-note b { color: var(--text); }

.src-code {
  margin: 0;
  padding: 22px;
  font-family: var(--mono);
  font-size: 0.84rem;
  line-height: 1.65;
  color: #cdd3ee;
  background: #05060d;
  overflow-x: auto;
  max-height: 540px;
  overflow-y: auto;
  white-space: pre;
  tab-size: 2;
}
.src-code .kw { color: #c792ea; }
.src-code .ty { color: #82aaff; }
.src-code .cm { color: #5c6480; font-style: italic; }
.src-code .str { color: #c3e88d; }

/* ============================== REVEAL ANIMATION ============================== */
.section-head, .cpu-demo, .sched-demo, .race-demo, .persist-demo, .trap-demo, .process-demo, .states-demo, .struct-demo, .layer-stack, .three-pillars, .fe-demo, .cs-demo, .rd, .xv6-about {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.revealed { opacity: 1 !important; transform: none !important; }

/* ============================== RESPONSIVE ============================== */
@media (max-width: 1000px) {
  #sidenav { transform: translateX(-100%); transition: transform 0.25s ease; }
  #sidenav.open { transform: translateX(0); }
  #nav-toggle { display: block; }
  main { margin-left: 0; }
  .cpu-demo, .sched-demo, .persist-demo, .trap-demo, .process-demo, .states-demo, .struct-demo, .fe-demo, .cs-demo { grid-template-columns: 1fr; }
  .pillar-grid, .xa-grid { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .section { padding: 60px 18px; }
  .race-stage { grid-template-columns: 1fr; }
  .hero h1 { font-size: 3rem; }
}