:root {
  color-scheme: light;
  --ink: #17211b;
  --muted: #5b675f;
  --paper: #f7f8f4;
  --surface: #ffffff;
  --line: #d6ddd7;
  --green: #176b4d;
  --green-soft: #dceee5;
  --red: #a33b2b;
  --yellow: #f2c14e;
  --blue: #246b91;
  --ghost: #7a7580;
  --code: #202923;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  font-size: 17px;
  line-height: 1.75;
  letter-spacing: 0;
}

a {
  color: var(--blue);
  text-underline-offset: 0.18em;
}

header,
main,
footer {
  width: min(920px, calc(100% - 32px));
  margin-inline: auto;
}

header {
  padding: 56px 0 28px;
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--green);
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  line-height: 1.28;
  letter-spacing: 0;
}

h1 {
  max-width: 760px;
  margin: 0;
  font-family: Georgia, "Noto Serif SC", serif;
  font-size: clamp(2.1rem, 7vw, 4.8rem);
  font-weight: 600;
}

.lede {
  max-width: 720px;
  margin: 18px 0 0;
  color: var(--muted);
  font-size: 1.14rem;
}

main {
  padding: 16px 0 64px;
}

section {
  padding: 42px 0;
  border-bottom: 1px solid var(--line);
}

h2 {
  margin: 0 0 18px;
  font-family: Georgia, "Noto Serif SC", serif;
  font-size: 1.75rem;
}

h3 {
  margin: 26px 0 8px;
  font-size: 1.05rem;
}

p,
ul,
ol {
  max-width: 760px;
}

.thesis {
  margin: 24px 0;
  padding: 18px 20px;
  border-left: 4px solid var(--green);
  background: var(--green-soft);
  font-family: Georgia, "Noto Serif SC", serif;
  font-size: 1.18rem;
}

.comparison,
.queue-grid {
  display: grid;
  gap: 12px;
}

.comparison {
  grid-template-columns: repeat(3, 1fr);
}

.queue-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 18px;
}

.panel {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
}

.panel strong {
  display: block;
  margin-bottom: 4px;
}

.panel p {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.queue-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 12px;
}

.queue-heading span {
  color: var(--muted);
  font-size: 0.76rem;
}

.queue {
  display: flex;
  min-height: 60px;
  gap: 7px;
  align-items: center;
  overflow-x: auto;
}

.queue::after {
  content: "空";
  color: #929a94;
  font-size: 0.84rem;
}

.queue:has(.object)::after {
  display: none;
}

.object {
  display: grid;
  flex: 0 0 48px;
  width: 48px;
  height: 48px;
  place-items: center;
  border: 1px solid var(--green);
  border-radius: 4px;
  background: var(--green-soft);
  color: var(--green);
  font-weight: 800;
  line-height: 1;
}

.object small {
  font-size: 0.64rem;
  font-weight: 600;
}

.ghost-object {
  border-style: dashed;
  border-color: var(--ghost);
  background: #f1eff2;
  color: var(--ghost);
}

.simulator {
  margin-top: 24px;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}

button {
  min-height: 42px;
  padding: 9px 14px;
  border: 1px solid var(--green);
  border-radius: 4px;
  background: var(--green);
  color: white;
  font: inherit;
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
}

button:hover,
button:focus-visible {
  background: #0f553c;
}

button.secondary {
  background: white;
  color: var(--green);
}

.trace {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin: 18px 0 8px;
}

.trace span {
  display: grid;
  width: 32px;
  height: 32px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--paper);
  font-family: ui-monospace, monospace;
  font-size: 0.84rem;
}

.trace span.current {
  border-color: var(--yellow);
  background: #fff4cf;
  color: #6a4a00;
  font-weight: 800;
}

.trace span.done {
  border-color: var(--green);
  color: var(--green);
}

.event-log {
  min-height: 56px;
  margin: 14px 0 0;
  padding: 12px 14px;
  border-left: 3px solid var(--yellow);
  background: #fffaf0;
  color: #4f4634;
}

.legend {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.78rem;
}

.flow {
  margin: 20px 0;
  padding: 0;
  list-style: none;
  counter-reset: flow;
}

.flow li {
  position: relative;
  margin: 0 0 12px;
  padding: 12px 16px 12px 50px;
  border: 1px solid var(--line);
  background: var(--surface);
}

.flow li::before {
  position: absolute;
  top: 12px;
  left: 14px;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--ink);
  color: white;
  content: counter(flow);
  counter-increment: flow;
  display: grid;
  place-items: center;
  font-size: 0.75rem;
  font-weight: 800;
}

.quiz-options {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  max-width: 720px;
}

.quiz-options button {
  min-height: 64px;
  background: white;
  color: var(--ink);
  border-color: var(--line);
  text-align: left;
}

.quiz-options button.correct {
  border-color: var(--green);
  background: var(--green-soft);
  color: var(--green);
}

.quiz-options button.wrong {
  border-color: var(--red);
  background: #fae9e5;
  color: var(--red);
}

.quiz-result {
  min-height: 32px;
  margin-top: 12px;
  font-weight: 700;
}

.caveat {
  border-left-color: var(--red);
  background: #fae9e5;
}

code {
  padding: 0.12em 0.35em;
  border-radius: 3px;
  background: #e8ece8;
  color: var(--code);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.88em;
}

footer {
  padding: 28px 0 54px;
  color: var(--muted);
  font-size: 0.86rem;
}

@media (max-width: 720px) {
  header {
    padding-top: 36px;
  }

  .comparison,
  .queue-grid,
  .quiz-options {
    grid-template-columns: 1fr;
  }

  section {
    padding: 32px 0;
  }

  .simulator {
    padding: 14px;
  }
}

@media print {
  body {
    background: white;
    font-size: 11pt;
  }

  button,
  .controls {
    display: none;
  }

  section {
    break-inside: avoid;
  }
}