:root {
  color-scheme: dark;
  --page: #0a0d0a;
  --surface: #111611;
  --surface-2: #171d17;
  --surface-3: #202720;
  --bone: #e6e0cf;
  --muted: #9da697;
  --line: #303a30;
  --line-strong: #4a5749;
  --orange: #ff7a1a;
  --orange-soft: #46240f;
  --amber: #dca44d;
  --green: #66d98b;
  --green-soft: #163522;
  --red: #ff6a63;
  --red-soft: #3b1715;
  --blue: #7eb9ff;
  --shadow: 0 22px 60px rgba(0, 0, 0, .32);
  --radius: 14px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 50% -20%, rgba(122, 149, 110, .18), transparent 36rem),
    var(--page);
  color: var(--bone);
  font-family: "Alexandria", system-ui, sans-serif;
  line-height: 1.65;
}
button, input, select, textarea { font: inherit; }
button, a, input, select, textarea { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
button { color: inherit; }

.app-frame { min-height: 100vh; }
.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: grid;
  grid-template-columns: auto minmax(180px, 420px) auto;
  align-items: center;
  gap: 24px;
  min-height: 72px;
  padding: 12px clamp(16px, 4vw, 56px);
  background: rgba(10, 13, 10, .9);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(16px);
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 700;
}
.brand-mark {
  display: inline-flex;
  gap: 3px;
  align-items: end;
  width: 26px;
  height: 22px;
}
.brand-mark i { display: block; width: 6px; border-radius: 2px 2px 0 0; background: var(--orange); }
.brand-mark i:nth-child(1) { height: 10px; }
.brand-mark i:nth-child(2) { height: 17px; }
.brand-mark i:nth-child(3) { height: 22px; }
.course-position { display: grid; grid-template-columns: auto 1fr; align-items: center; gap: 12px; color: var(--muted); font-size: .82rem; }
.course-track { height: 6px; overflow: hidden; border-radius: 999px; background: var(--surface-3); }
.course-track span { display: block; width: 7.15%; height: 100%; background: var(--orange); }
.mastery-chip {
  justify-self: end;
  padding: 7px 12px;
  border-radius: 999px;
  background: var(--surface-3);
  color: var(--muted);
  font-size: .78rem;
  white-space: nowrap;
}
.mastery-chip[data-state="mastered"] { background: var(--green-soft); color: var(--green); }

.lab-page { width: min(1480px, calc(100% - 32px)); margin: 0 auto; padding: 44px 0 80px; }
.lesson-intro {
  display: flex;
  justify-content: space-between;
  gap: 36px;
  align-items: end;
  margin-bottom: 28px;
}
.lesson-intro h1 {
  max-width: 850px;
  margin: 0 0 12px;
  font-size: clamp(2.1rem, 5vw, 4.8rem);
  line-height: 1.08;
  letter-spacing: -.035em;
}
.lesson-intro p { max-width: 780px; margin: 0; color: var(--muted); font-size: clamp(1rem, 1.7vw, 1.2rem); }
.lesson-readout {
  min-width: 250px;
  padding: 16px 18px;
  border-top: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
}
.lesson-readout span { display: block; margin-bottom: 4px; color: var(--amber); font-size: .76rem; }
.lesson-readout strong { font-size: .95rem; }

.control-room {
  display: grid;
  grid-template-columns: minmax(300px, .9fr) minmax(430px, 1.35fr) minmax(320px, 1fr);
  grid-template-areas:
    "form pipeline inspector"
    "form terminal inspector";
  gap: 14px;
  align-items: stretch;
}
.panel {
  border-radius: var(--radius);
  background: linear-gradient(180deg, var(--surface-2), var(--surface));
  box-shadow: var(--shadow);
}
.form-console { grid-area: form; padding: 20px; }
.pipeline-console { grid-area: pipeline; padding: 20px; overflow: hidden; }
.inspector-console { grid-area: inspector; padding: 20px; min-width: 0; }
.terminal-console { grid-area: terminal; padding: 18px 20px; min-height: 220px; }
.panel-heading, .terminal-heading, .challenge-heading, .model-title, .model-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}
.panel-heading { padding-bottom: 16px; border-bottom: 1px solid var(--line); }
.panel-heading h2, .terminal-heading h2 { margin: 0; font-size: 1rem; letter-spacing: -.01em; }
.panel-heading p { margin: 3px 0 0; color: var(--muted); font-size: .75rem; }
.live-lamp, .run-state {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: var(--muted);
  font: 500 .7rem "IBM Plex Mono", monospace;
  text-transform: uppercase;
}
.live-lamp i, .run-state i {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--green);
  box-shadow: 0 0 0 4px rgba(102, 217, 139, .08);
}
.run-state[data-state="running"] { color: var(--amber); }
.run-state[data-state="running"] i { background: var(--amber); animation: pulse 1s infinite; }
.run-state[data-state="blocked"] { color: var(--red); }
.run-state[data-state="blocked"] i { background: var(--red); }
.run-state[data-state="saved"] { color: var(--green); }

form { display: grid; gap: 14px; margin-top: 18px; }
label span { display: block; margin-bottom: 7px; color: var(--muted); font-size: .76rem; }
input, select, textarea {
  width: 100%;
  border: 1px solid transparent;
  border-radius: 10px;
  background: var(--surface-3);
  color: var(--bone);
  padding: 12px 13px;
  outline: none;
}
textarea { min-height: 104px; resize: vertical; }
input:focus, select:focus, textarea:focus { border-color: var(--orange); box-shadow: 0 0 0 3px rgba(255, 122, 26, .12); }
.field-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.fault-bench { margin-top: 18px; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.toggle-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 13px 0;
  cursor: pointer;
}
.toggle-row + .toggle-row { border-top: 1px solid var(--line); }
.toggle-row span { margin: 0; }
.toggle-row strong { display: block; font-size: .78rem; }
.toggle-row small { color: var(--muted); font-size: .66rem; }
.toggle-row input {
  appearance: none;
  position: relative;
  width: 42px;
  height: 24px;
  flex: 0 0 42px;
  padding: 0;
  border: 0;
  border-radius: 999px;
  background: #333d33;
  cursor: pointer;
}
.toggle-row input::after {
  content: "";
  position: absolute;
  top: 4px;
  right: 4px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--bone);
  transition: transform .18s ease-out;
}
.toggle-row input:checked { background: var(--red-soft); box-shadow: inset 0 0 0 1px var(--red); }
.toggle-row input:checked::after { transform: translateX(-18px); background: var(--red); }
.toggle-row input:focus-visible { outline: 3px solid var(--orange); outline-offset: 3px; }
.action-row { display: grid; grid-template-columns: 1fr auto; gap: 10px; margin-top: 18px; }
.run-button, .reset-button, .copy-state, .inspector-tabs button, .segmented-control button, .next-lesson {
  border: 0;
  cursor: pointer;
}
.run-button {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 52px;
  padding: 0 16px;
  border-radius: 11px;
  background: var(--orange);
  color: #160a03;
  font-weight: 700;
  box-shadow: 0 10px 24px rgba(255, 122, 26, .2);
}
.run-button:active { transform: translateY(2px); box-shadow: 0 6px 14px rgba(255, 122, 26, .16); }
.run-button:disabled { cursor: wait; opacity: .62; }
.run-button kbd { font: 500 .65rem "IBM Plex Mono", monospace; opacity: .7; }
.reset-button, .copy-state {
  border-radius: 10px;
  background: var(--surface-3);
  color: var(--muted);
  padding: 0 14px;
}
.copy-state { padding: 8px 10px; font-size: .68rem; }
button:focus-visible, a:focus-visible { outline: 3px solid var(--orange); outline-offset: 3px; }

.pipeline {
  position: relative;
  z-index: 2;
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 8px;
  margin: 18px 0 10px;
  padding: 0;
  list-style: none;
  direction: ltr;
}
.pipeline li { min-width: 0; }
.pipeline button {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  width: 100%;
  min-height: 112px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #111511;
  text-align: left;
  transition: border-color .18s ease-out, transform .18s ease-out, background .18s ease-out;
}
.pipeline button:hover { transform: translateY(-3px); border-color: var(--line-strong); }
.pipeline button > span { color: var(--muted); font: 500 .65rem "IBM Plex Mono", monospace; }
.pipeline button strong { margin-top: auto; font-size: .72rem; }
.pipeline button small { color: var(--muted); font: 400 .58rem "IBM Plex Mono", monospace; white-space: nowrap; }
.pipeline button i {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #465046;
}
.pipeline button[aria-current="step"] { border-color: var(--blue); background: #14202b; }
.pipeline button[data-state="active"] { border-color: var(--amber); background: #261e12; }
.pipeline button[data-state="active"] i { background: var(--amber); animation: pulse .8s infinite; }
.pipeline button[data-state="complete"] { border-color: var(--green); background: var(--green-soft); }
.pipeline button[data-state="complete"] i { background: var(--green); }
.pipeline button[data-state="error"] { border-color: var(--red); background: var(--red-soft); }
.pipeline button[data-state="error"] i { background: var(--red); }
.signal-rail {
  position: relative;
  height: 14px;
  margin: 0 5%;
  border-top: 1px solid var(--line-strong);
  direction: ltr;
}
.signal-rail::before, .signal-rail::after { content: ""; position: absolute; top: -3px; width: 5px; height: 5px; border-radius: 50%; background: var(--line-strong); }
.signal-rail::before { left: 0; }
.signal-rail::after { right: 0; }
#signalPacket {
  position: absolute;
  top: -6px;
  left: 0;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--orange);
  box-shadow: 0 0 0 5px rgba(255, 122, 26, .12);
  transform: translateX(-50%);
  opacity: 0;
  transition: left .42s cubic-bezier(.2, .8, .2, 1), opacity .15s ease-out;
}
#signalPacket[data-visible="true"] { opacity: 1; }
.stage-explainer {
  display: grid;
  grid-template-columns: minmax(150px, .7fr) 1.5fr auto;
  gap: 18px;
  align-items: center;
  min-height: 98px;
  margin-top: 8px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}
.stage-explainer div span { display: block; color: var(--muted); font-size: .64rem; }
.stage-explainer div strong { font-size: .9rem; }
.stage-explainer p { margin: 0; color: var(--muted); font-size: .78rem; }
.stage-explainer code, .model-footer code { direction: ltr; color: var(--amber); font: 500 .72rem "IBM Plex Mono", monospace; }

.inspector-tabs { display: grid; grid-template-columns: repeat(4, 1fr); gap: 4px; margin: 14px 0 10px; padding: 4px; border-radius: 10px; background: #0d110d; }
.inspector-tabs button { min-width: 0; padding: 8px 6px; border-radius: 7px; background: transparent; color: var(--muted); font: 500 .64rem "IBM Plex Mono", monospace; }
.inspector-tabs button[aria-selected="true"] { background: var(--surface-3); color: var(--bone); }
pre {
  min-height: 390px;
  max-height: 520px;
  margin: 0;
  overflow: auto;
  border-radius: 11px;
  background: #080b08;
  color: #d9e5d7;
  padding: 16px;
  direction: ltr;
  text-align: left;
  white-space: pre-wrap;
  word-break: break-word;
  font: 400 .72rem/1.7 "IBM Plex Mono", monospace;
}
pre:focus-visible { outline: 2px solid var(--orange); outline-offset: 2px; }
.terminal-heading { padding-bottom: 10px; }
.terminal-heading span { color: var(--muted); font: 500 .64rem "IBM Plex Mono", monospace; }
.event-log { max-height: 164px; margin: 0; padding: 0; overflow: auto; list-style: none; direction: ltr; }
.event-log li { display: grid; grid-template-columns: 76px 1fr; gap: 10px; padding: 6px 0; border-top: 1px solid rgba(48, 58, 48, .55); color: var(--muted); font: 400 .69rem/1.5 "IBM Plex Mono", monospace; }
.event-log time { color: #657064; }
.event-log li[data-kind="success"] span { color: var(--green); }
.event-log li[data-kind="error"] span { color: var(--red); }
.event-log li[data-kind="active"] span { color: var(--amber); }

.model-bench {
  display: grid;
  grid-template-columns: minmax(280px, .8fr) minmax(480px, 1.4fr);
  gap: 32px;
  align-items: center;
  margin-top: 74px;
  padding: 38px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.model-copy h2, .challenge-heading h2, .completion-panel h2 { margin: 0 0 10px; font-size: clamp(1.6rem, 3vw, 2.6rem); line-height: 1.2; letter-spacing: -.025em; }
.model-copy p, .challenge-heading p, .completion-panel p { margin: 0; color: var(--muted); }
.segmented-control { display: inline-grid; grid-template-columns: 1fr 1fr; gap: 4px; margin-top: 22px; padding: 4px; border-radius: 12px; background: var(--surface-2); }
.segmented-control button { padding: 10px 18px; border-radius: 9px; background: transparent; color: var(--muted); }
.segmented-control button[aria-pressed="true"] { background: var(--orange); color: #160a03; font-weight: 700; }
.model-visual { border-radius: var(--radius); background: var(--surface-2); padding: 22px; box-shadow: var(--shadow); }
.model-title { padding-bottom: 16px; border-bottom: 1px solid var(--line); }
.model-title span { color: var(--amber); font: 500 .68rem "IBM Plex Mono", monospace; }
.model-title strong { font-size: 1rem; }
.schema-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; margin: 16px 0; }
.schema-field { min-width: 0; padding: 12px; border-radius: 10px; background: #0d110d; }
.schema-field span { display: block; color: var(--muted); font: 400 .62rem "IBM Plex Mono", monospace; }
.schema-field strong { display: block; margin-top: 4px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: .76rem; }
.model-footer { padding-top: 14px; border-top: 1px solid var(--line); color: var(--muted); font-size: .7rem; }

.challenge-zone { margin-top: 74px; }
.challenge-heading { align-items: end; margin-bottom: 22px; }
.score-readout { min-width: 140px; text-align: left; direction: ltr; }
.score-readout span { display: block; color: var(--muted); font: 500 .68rem "IBM Plex Mono", monospace; }
.score-readout strong { font: 600 1.8rem "IBM Plex Mono", monospace; }
.challenge-list { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.challenge { min-width: 0; margin: 0; padding: 20px; border: 0; border-radius: var(--radius); background: var(--surface-2); box-shadow: var(--shadow); }
.challenge legend { min-height: 62px; padding: 0; font-weight: 600; line-height: 1.5; }
.challenge label {
  display: flex;
  align-items: flex-start;
  gap: 9px;
  min-height: 48px;
  margin-top: 8px;
  padding: 10px;
  border-radius: 10px;
  background: #0d110d;
  color: var(--muted);
  cursor: pointer;
  font-size: .75rem;
}
.challenge label:hover { color: var(--bone); }
.challenge input { width: auto; margin-top: 4px; accent-color: var(--orange); }
.challenge-feedback { min-height: 48px; margin: 12px 0 0; color: var(--muted); font-size: .72rem; }
.challenge[data-state="correct"] { background: var(--green-soft); }
.challenge[data-state="correct"] .challenge-feedback { color: var(--green); }
.challenge[data-state="wrong"] { background: var(--red-soft); }
.challenge[data-state="wrong"] .challenge-feedback { color: var(--red); }

.completion-panel {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 24px;
  align-items: center;
  margin-top: 28px;
  padding: 28px;
  border-radius: var(--radius);
  background: var(--surface-2);
}
.completion-state { display: inline-block; margin-bottom: 8px; color: var(--amber); font: 500 .7rem "IBM Plex Mono", monospace; text-transform: uppercase; }
.next-lesson {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 18px;
  border-radius: 11px;
  background: var(--orange);
  color: #160a03;
  text-decoration: none;
  font-weight: 700;
}
.next-lesson[aria-disabled="true"] { pointer-events: none; background: var(--surface-3); color: #657064; }
.completion-panel[data-state="mastered"] { background: var(--green-soft); }
.completion-panel[data-state="mastered"] .completion-state { color: var(--green); }
.lesson-footer { display: flex; justify-content: space-between; gap: 20px; padding-top: 30px; color: var(--muted); font-size: .72rem; }
.lesson-footer p { margin: 0; }
.lesson-footer div { display: flex; gap: 14px; }
.lesson-footer a { color: var(--blue); }

@keyframes pulse { 50% { opacity: .35; } }

@media (max-width: 1180px) {
  .control-room {
    grid-template-columns: minmax(300px, .8fr) minmax(500px, 1.3fr);
    grid-template-areas:
      "form pipeline"
      "inspector terminal";
  }
  .inspector-console { min-height: 480px; }
  pre { min-height: 330px; }
}

@media (max-width: 820px) {
  .topbar { grid-template-columns: 1fr auto; gap: 12px; }
  .course-position { grid-column: 1 / -1; grid-row: 2; }
  .lab-page { width: min(100% - 20px, 720px); padding-top: 28px; }
  .lesson-intro { display: grid; align-items: start; }
  .lesson-readout { min-width: 0; }
  .control-room { grid-template-columns: 1fr; grid-template-areas: "form" "pipeline" "inspector" "terminal"; }
  .pipeline { grid-template-columns: repeat(3, 1fr); direction: rtl; }
  .signal-rail { display: none; }
  .stage-explainer { grid-template-columns: 1fr; gap: 8px; }
  .model-bench { grid-template-columns: 1fr; gap: 22px; }
  .challenge-list { grid-template-columns: 1fr; }
  .challenge legend { min-height: 0; }
  .completion-panel { grid-template-columns: 1fr; }
  .lesson-footer { display: grid; }
}

@media (max-width: 520px) {
  .topbar { padding-inline: 12px; }
  .brand { font-size: .9rem; }
  .mastery-chip { padding: 6px 9px; font-size: .66rem; }
  .lesson-intro h1 { font-size: 2.15rem; }
  .panel, .model-visual, .challenge, .completion-panel { border-radius: 12px; }
  .form-console, .pipeline-console, .inspector-console, .terminal-console { padding: 16px; }
  .field-pair { grid-template-columns: 1fr; }
  .pipeline { grid-template-columns: repeat(2, 1fr); }
  .pipeline button { min-height: 100px; }
  .inspector-tabs { grid-template-columns: repeat(2, 1fr); }
  pre { min-height: 300px; max-height: 420px; font-size: .66rem; }
  .schema-grid { grid-template-columns: repeat(2, 1fr); }
  .challenge-heading { display: grid; align-items: start; }
  .score-readout { text-align: right; direction: rtl; }
  .action-row { grid-template-columns: 1fr; }
  .reset-button { min-height: 44px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation: none !important; transition-duration: .01ms !important; }
}