:root {
  --bg: #0d0e11;
  --bg-2: #14161b;
  --panel: #1a1d23;
  --panel-2: #22262e;
  --line: #2e333d;
  --text: #e9eaee;
  --muted: #9aa0ab;
  --red: #ff3b3b;
  --red-glow: rgba(255, 59, 59, .55);
  --amber: #ffb547;
  --lan: #47d18c;
  --cloud: #5aa9ff;
  --code-bg: #101216;
  --radius: 12px;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  background: radial-gradient(1200px 600px at 80% -10%, #1b1416 0%, var(--bg) 60%) fixed, var(--bg);
  color: var(--text);
  font: 17px/1.55 var(--sans);
  overflow: hidden;
}
a { color: var(--cloud); }
code { font-family: var(--mono); font-size: .88em; background: var(--panel-2); padding: .1em .35em; border-radius: 5px; }
kbd { font-family: var(--mono); font-size: .8em; border: 1px solid var(--line); border-bottom-width: 2px; border-radius: 5px; padding: 0 .4em; background: var(--panel); }
button { font: inherit; color: inherit; cursor: pointer; }

/* ---------- chrome ---------- */
.topbar, .bottombar {
  position: fixed; left: 0; right: 0; z-index: 10;
  display: flex; align-items: center; gap: 14px;
  padding: 10px 20px;
  background: rgba(13, 14, 17, .82); backdrop-filter: blur(8px);
}
.topbar { top: 0; border-bottom: 1px solid var(--line); }
.bottombar { bottom: 0; border-top: 1px solid var(--line); }
.brand { display: flex; align-items: center; gap: 8px; color: var(--text); text-decoration: none; font-weight: 700; letter-spacing: .06em; font-size: 14px; }
.brand-dot { width: 10px; height: 10px; border-radius: 50%; background: var(--red); box-shadow: 0 0 10px var(--red-glow); }
.chapter { flex: 1; color: var(--muted); font-size: 14px; text-align: right; }
.icon-btn { background: var(--panel); border: 1px solid var(--line); border-radius: 8px; width: 38px; height: 34px; display: grid; place-items: center; }
.icon-btn:hover { border-color: var(--muted); }
.progress { flex: 1; height: 4px; background: var(--panel-2); border-radius: 4px; overflow: hidden; }
#progress-fill { height: 100%; width: 0; background: var(--red); transition: width .3s; }
.counter { font-family: var(--mono); font-size: 13px; color: var(--muted); min-width: 52px; text-align: center; }

/* ---------- slides ---------- */
#deck { position: fixed; inset: 55px 0 55px 0; }
.slide {
  position: absolute; inset: 0;
  padding: 28px max(16px, calc((100vw - 1200px) / 2)) 28px;
  overflow-y: auto;
  opacity: 0; visibility: hidden; transform: translateX(30px);
  transition: opacity .35s, transform .35s, visibility .35s;
}
.slide.active { opacity: 1; visibility: visible; transform: none; }
.slide.before { transform: translateX(-30px); }
h1 { font-size: clamp(34px, 5vw, 58px); line-height: 1.1; margin: .2em 0 .3em; letter-spacing: -.01em; }
h2 { font-size: clamp(24px, 3vw, 36px); margin: 0 0 .3em; letter-spacing: -.01em; }
h2 code { font-size: .8em; }
h3 { margin: 0 0 .5em; font-size: 18px; }
.sub { color: var(--muted); margin: 0 0 18px; }
.lead { font-size: 1.15em; }
.kicker { color: var(--red); font-family: var(--mono); font-size: 13px; letter-spacing: .08em; text-transform: uppercase; margin: 0; }
.hint { color: var(--muted); font-size: 15px; }
.muted { color: var(--muted); }
.small-text { font-size: 14px; }
.note { border-left: 3px solid var(--amber); background: rgba(255, 181, 71, .08); padding: 8px 12px; border-radius: 0 8px 8px 0; font-size: 15px; }

.cols { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; align-items: start; }
.cols.wide-left { grid-template-columns: 1.4fr 1fr; }
.cols.wide-right { grid-template-columns: 1fr 1.6fr; }
.card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 20px; }
.card.center { text-align: center; }
.points { padding-left: 1.1em; margin: 0; }
.points li { margin-bottom: .7em; }
.row { display: flex; gap: 8px; align-items: center; margin-top: 12px; }
.row.wrap { flex-wrap: wrap; }
.info-box { background: var(--bg-2); border: 1px solid var(--line); border-radius: 8px; padding: 10px 14px; min-height: 3em; font-size: 15px; }

.btn { background: var(--panel-2); border: 1px solid var(--line); border-radius: 8px; padding: 7px 14px; }
.btn:hover { border-color: var(--muted); }
.btn.primary { background: var(--red); border-color: var(--red); color: #fff; font-weight: 600; }
.btn.ghost { background: transparent; }
.btn:disabled { opacity: .4; cursor: default; }
.chip { background: var(--panel); border: 1px solid var(--line); border-radius: 999px; padding: 6px 14px; font-size: 14px; }
.chip.active { border-color: var(--red); color: #fff; background: rgba(255, 59, 59, .15); }
.scenario-bar, .tabs { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 18px; }

pre.code {
  background: var(--code-bg); border: 1px solid var(--line); border-radius: 10px;
  padding: 12px 14px; margin: 10px 0; overflow-x: auto;
  font: 13.5px/1.5 var(--mono); white-space: pre;
}
pre.code.tall { font-size: 13px; }
pre.code .c { color: #6f7785; }
pre.code:empty { display: none; }

/* ---------- the sign ---------- */
.sign {
  --level: 0;
  display: inline-grid; place-items: center;
  border: 3px solid rgba(255, 255, 255, calc(.12 + var(--level) * .8));
  border-radius: 16px; background: #0a0a0c;
  box-shadow: 0 0 calc(var(--level) * 40px) rgba(255, 255, 255, calc(var(--level) * .25)), inset 0 0 calc(var(--level) * 20px) rgba(255, 255, 255, calc(var(--level) * .15));
  color: rgb(calc(70 + var(--level) * 185), calc(30 + var(--level) * 29), calc(30 + var(--level) * 29));
  font-weight: 800; letter-spacing: .06em;
  text-shadow: 0 0 calc(var(--level) * 18px) var(--red-glow), 0 0 calc(var(--level) * 4px) var(--red);
  padding: 0;
}
.sign span { padding: .25em .6em; }
.sign.big { font-size: clamp(36px, 6vw, 72px); }
.sign.tiny { font-size: 14px; border-width: 2px; border-radius: 6px; }
.sign.tiny span { padding: .15em .5em; }
.hero { display: grid; grid-template-columns: 1.2fr 1fr; gap: 40px; align-items: center; min-height: 100%; }
#hero-sign { transition: all .25s; }

.photo { margin: 0; }
.photo img, .shot { width: 100%; border-radius: var(--radius); border: 1px solid var(--line); display: block; }
.shot { margin-top: 12px; }
.photo figcaption { color: var(--muted); font-size: 14px; margin-top: 6px; }

/* ---------- architecture ---------- */
.arch { position: relative; aspect-ratio: 600 / 340; width: 100%; }
.arch-lines { position: absolute; inset: 0; width: 100%; height: 100%; z-index: 0; }
.ln { fill: none; stroke-width: 3; stroke-dasharray: 8 6; animation: dash 1.2s linear infinite; }
.ln.lan { stroke: var(--lan); }
.ln.cloud { stroke: var(--cloud); }
@keyframes dash { to { stroke-dashoffset: -28; } }
.arch-node {
  position: absolute; z-index: 1; width: 27%; padding: 10px;
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  display: flex; flex-direction: column; text-align: center; transition: border-color .2s, transform .2s;
}
.arch-node small { color: var(--muted); font-size: 13px; }
.arch-node:hover, .arch-node.active { border-color: var(--red); transform: translateY(-2px); }
.n-ext { left: 4%; top: 44%; }
.n-dev { right: 4%; top: 44%; }
.n-lam { left: 36%; top: 8%; width: 26%; }
.n-iot { right: 4%; top: 8%; }
.arch-tag { position: absolute; font-size: 12px; font-family: var(--mono); }
.t-lan { left: 50%; bottom: 2%; transform: translateX(-50%); color: var(--lan); }
.t-cloud { left: 34%; top: 0; color: var(--cloud); }

/* ---------- flow ---------- */
.flow { width: 100%; height: auto; }
.fp { fill: none; stroke: var(--line); stroke-width: 3; transition: stroke .3s; }
.fp.hot { stroke: var(--amber); }
.fp.done { stroke: #4a505c; }
.fn rect { fill: var(--panel); stroke: var(--line); stroke-width: 2; transition: stroke .3s, fill .3s; }
.fn.hot rect { stroke: var(--amber); fill: #2a2418; }
.fn text { fill: var(--text); text-anchor: middle; font-size: 18px; font-weight: 600; }
.fn text.small { fill: var(--muted); font-size: 13px; font-weight: 400; }
.lane { fill: var(--lan); text-anchor: middle; font: 13px var(--mono); }
#packet { fill: var(--amber); filter: drop-shadow(0 0 6px var(--amber)); }
.flow-x line { stroke: var(--red); stroke-width: 6; stroke-linecap: round; }
.steps { padding-left: 1.3em; margin: 0; }
.steps li { margin: 0 0 .55em; color: var(--muted); transition: color .2s; font-size: 15px; }
.steps li.cur { color: var(--text); }
.steps li.cur::marker { color: var(--amber); font-weight: 700; }
.steps.static li { color: var(--text); }
.mini-sign-row { display: flex; gap: 10px; align-items: center; margin-top: 14px; color: var(--muted); font-size: 14px; }

/* ---------- schematic ---------- */
.schematic { width: 100%; height: auto; }
.wire path { fill: none; stroke: #6b7280; stroke-width: 2.5; }
.lbl { fill: var(--muted); font: 13px var(--mono); }
.part rect { fill: var(--panel); stroke: var(--line); stroke-width: 2; transition: all .2s; }
.part text { fill: var(--text); text-anchor: middle; font-size: 15px; font-weight: 600; pointer-events: none; }
.part text.small, .schematic text.small { font-size: 12px; font-weight: 400; fill: var(--muted); }
.part { cursor: pointer; }
.part:hover rect, .part.active rect { stroke: var(--red); fill: #2a1a1c; }
.pin { font-family: var(--mono); }

/* ---------- files / loop ---------- */
.files { display: grid; gap: 8px; margin-bottom: 14px; }
.file { background: var(--panel); border: 1px solid var(--line); border-radius: 10px; padding: 8px 12px; display: flex; flex-direction: column; }
.file span { color: var(--muted); font-size: 14px; }
.file code { background: none; padding: 0; color: var(--amber); }
.loop-list { padding-left: 1.6em; margin: 0 0 12px; }
.loop-list li { padding: 3px 6px; border-radius: 6px; cursor: pointer; }
.loop-list li code { background: none; }
.loop-list li:hover, .loop-list li.active { background: var(--panel-2); }
.loop-list li.active code { color: var(--amber); }
.loop-list li.pulse { background: rgba(255, 181, 71, .14); }

/* ---------- boot walkthrough ---------- */
.trail { list-style: none; padding: 0; margin: 0; position: relative; }
.trail li { position: relative; padding: 6px 10px 6px 26px; font-size: 14px; color: var(--muted); }
.trail li::before { content: ""; position: absolute; left: 7px; top: 12px; width: 10px; height: 10px; border-radius: 50%; background: var(--line); }
.trail li::after { content: ""; position: absolute; left: 11px; top: 24px; bottom: -8px; width: 2px; background: var(--line); }
.trail li:last-child::after { display: none; }
.trail li.cur { color: var(--text); font-weight: 600; }
.trail li.cur::before { background: var(--red); box-shadow: 0 0 8px var(--red-glow); }
.trail li .ch { display: block; font-weight: 400; color: var(--amber); font-size: 12px; }
.boot-head { display: flex; justify-content: space-between; align-items: center; gap: 10px; }
.boot-card p { margin-top: 0; }

/* ---------- generator ---------- */
.kv { display: grid; grid-template-columns: max-content 1fr; gap: 8px 14px; margin: 10px 0 16px; }
.kv dt { color: var(--muted); }
.kv dd { margin: 0; min-width: 0; }
.big-code { font-size: 1.1em; color: var(--amber); }
.wrapcode { word-break: break-all; }

/* ---------- output sim ---------- */
.sim { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; }
.sim-top { display: flex; align-items: center; justify-content: space-around; gap: 16px; flex-wrap: wrap; margin-bottom: 14px; }
.sim-top .sign { cursor: default; }
.led-box { display: flex; flex-direction: column; align-items: center; gap: 6px; color: var(--muted); }
.led { display: inline-block; width: 18px; height: 18px; border-radius: 50%; background: #2b3a2f; border: 1px solid #3a4a3e; transition: background .05s; }
.led.on { background: #7dff9b; box-shadow: 0 0 12px #7dff9b; }
.led.huge { width: 34px; height: 34px; }
#sim-graph { width: 100%; height: 160px; display: block; background: var(--code-bg); border-radius: 8px; border: 1px solid var(--line); }
.readout { display: flex; gap: 18px; flex-wrap: wrap; font: 13px var(--mono); color: var(--muted); margin-top: 10px; }
.readout b { color: var(--text); }
.seg { display: flex; border: 1px solid var(--line); border-radius: 10px; overflow: hidden; margin-bottom: 14px; }
.seg button { flex: 1; background: var(--panel-2); border: 0; padding: 8px; border-right: 1px solid var(--line); }
.seg button:last-child { border-right: 0; }
.seg button.active { background: var(--red); color: #fff; font-weight: 600; }
.slider { display: block; font: 14px var(--mono); color: var(--muted); margin-bottom: 8px; }
.slider output { float: right; color: var(--text); }
.slider input { width: 100%; accent-color: var(--red); }
.cmds { display: grid; gap: 8px; margin-top: 10px; }
.cmds div { display: flex; flex-direction: column; gap: 2px; }
.cmds small { color: var(--muted); font-size: 12px; }
.cmds code { word-break: break-all; }

/* ---------- api ---------- */
.field { display: block; font-size: 14px; color: var(--muted); margin-bottom: 10px; }
.field select, .field input { display: block; width: 100%; margin-top: 4px; background: var(--code-bg); color: var(--text); border: 1px solid var(--line); border-radius: 8px; padding: 8px 10px; font: 14px var(--mono); }

/* ---------- boot button ---------- */
.boot-sim { display: flex; align-items: center; justify-content: center; gap: 30px; margin: 10px 0 20px; }
.boot-btn {
  width: 130px; height: 130px; border-radius: 50%;
  background: radial-gradient(circle at 35% 30%, #3a3f49, #1c1f25);
  border: 3px solid var(--line); box-shadow: 0 8px 0 #0a0b0d, 0 10px 20px rgba(0,0,0,.5);
  font-weight: 800; font-size: 22px; letter-spacing: .08em; display: flex; flex-direction: column; align-items: center; justify-content: center;
  user-select: none; touch-action: none; transition: transform .05s, box-shadow .05s;
}
.boot-btn small { font-size: 11px; font-weight: 400; color: var(--muted); letter-spacing: 0; }
.boot-btn.pressed { transform: translateY(6px); box-shadow: 0 2px 0 #0a0b0d, 0 4px 10px rgba(0,0,0,.5); border-color: var(--amber); }
.timeline { position: relative; height: 14px; background: var(--panel-2); border-radius: 8px; margin: 24px 4px 30px; }
.tl-fill { height: 100%; width: 0; border-radius: 8px; background: var(--lan); }
.tl-fill.warn { background: var(--amber); }
.tl-fill.danger { background: var(--red); }
.tl-mark { position: absolute; top: 18px; transform: translateX(-50%); font: 12px var(--mono); color: var(--muted); }
.tl-mark::before { content: ""; position: absolute; left: 50%; top: -22px; height: 18px; width: 2px; background: var(--muted); }
.bb-status { min-height: 3em; font-weight: 600; }
.check { font-size: 14px; color: var(--muted); }
.ns-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-bottom: 14px; }
.ns { background: var(--panel); border: 2px solid var(--line); border-radius: 10px; padding: 10px; display: flex; flex-direction: column; gap: 4px; transition: all .3s; }
.ns b { font-family: var(--mono); }
.ns small { color: var(--muted); font-size: 12px; }
.ns.armed { border-color: var(--amber); }
.ns.wiped { border-color: var(--red); background: #2a1517; }
.ns.wiped b { text-decoration: line-through; }
.ns.kept { border-color: var(--lan); }
.tbl { width: 100%; border-collapse: collapse; font-size: 14px; margin-bottom: 12px; }
.tbl th, .tbl td { text-align: left; padding: 6px 8px; border-bottom: 1px solid var(--line); }
.tbl th { color: var(--muted); font-weight: 500; }

/* ---------- wifi ---------- */
.wifi-bar { position: relative; height: 12px; background: var(--panel-2); border-radius: 6px; margin: 12px 0 30px; }
#wifi-fill { height: 100%; width: 0; background: var(--amber); border-radius: 6px; }
.wifi-bar span { position: absolute; top: 16px; transform: translateX(-50%); font: 12px var(--mono); color: var(--red); }
.layers { padding-left: 1.2em; margin: 0; }
.layers li { margin-bottom: .8em; }

/* ---------- aws ---------- */
.topic { margin-bottom: 12px; }
.topic > code { background: none; padding: 0; color: var(--amber); }
.topic pre.code { margin: 4px 0 0; font-size: 12.5px; }
.dir { display: inline-block; font: 11px var(--mono); padding: 1px 8px; border-radius: 999px; margin-right: 6px; }
.dir.in { background: rgba(90, 169, 255, .15); color: var(--cloud); }
.dir.out { background: rgba(71, 209, 140, .15); color: var(--lan); }

/* ---------- flash map ---------- */
.flashmap { display: flex; height: 64px; border-radius: 10px; overflow: hidden; border: 1px solid var(--line); margin-bottom: 12px; }
.fm { display: grid; place-items: center; font: 12px var(--mono); color: #0d0e11; font-weight: 700; cursor: pointer; border-right: 1px solid rgba(0,0,0,.4); min-width: 0; overflow: hidden; transition: filter .2s; }
.fm:hover, .fm.active { filter: brightness(1.25); }
.fm.boot { background: #8b93a1; }
.fm.nvs { background: var(--amber); }
.fm.otad { background: #d58cff; }
.fm.app { background: var(--cloud); }
.fm.app.alt { background: #7fbcff; }
.fm.sp { background: #4a505c; color: var(--text); }

/* ---------- principles ---------- */
.grid4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.tile { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px; border-top: 3px solid var(--red); }
.tile p { color: var(--muted); font-size: 14.5px; margin: .4em 0 0; }
.end-links { margin-top: 22px; text-align: center; }

/* ---------- overview ---------- */
.overview { position: fixed; inset: 0; z-index: 20; background: rgba(8, 9, 11, .94); overflow-y: auto; }
.overview-inner { max-width: 1100px; margin: 0 auto; padding: 24px 16px; }
.overview-head { display: flex; justify-content: space-between; align-items: center; }
#overview-list { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; counter-reset: ov; }
#overview-list a { display: block; background: var(--panel); border: 1px solid var(--line); border-radius: 10px; padding: 14px; color: var(--text); text-decoration: none; height: 100%; }
#overview-list a:hover, #overview-list a.cur { border-color: var(--red); }
#overview-list small { display: block; color: var(--muted); font-size: 12px; font-family: var(--mono); }

/* ---------- responsive ---------- */
@media (max-width: 860px) {
  body { font-size: 16px; }
  .cols, .cols.wide-left, .cols.wide-right, .hero { grid-template-columns: 1fr; gap: 18px; }
  .grid4 { grid-template-columns: 1fr 1fr; }
  .ns-grid { grid-template-columns: 1fr; }
  .arch-node { padding: 6px; font-size: 13px; }
  .arch-node small { display: none; }
  .chapter { display: none; }
  .topbar, .bottombar { padding: 8px 16px; }
  .hero { min-height: 0; }
}
@media (max-width: 480px) { .grid4 { grid-template-columns: 1fr; } }
@media (prefers-reduced-motion: reduce) {
  .slide, .ln { transition: none; animation: none; }
}