:root {
  --bg: #0b0f0f;
  --panel: #111716;
  --panel-2: #151d1c;
  --line: #2a3634;
  --text: #f1f5f3;
  --muted: #aebbb7;
  --green: #63d69a;
  --amber: #f3b85b;
  --red: #ff7d73;
  --blue: #76b8ff;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at 12% 10%, rgba(99, 214, 154, .08), transparent 25rem),
    var(--bg);
  font: 16px/1.7 Inter, "PingFang SC", "Microsoft YaHei", sans-serif;
}

button, input { font: inherit; }
button { min-height: 42px; }

.site-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
  padding: 18px clamp(20px, 4vw, 64px);
  border-bottom: 1px solid var(--line);
}

.site-header a { color: var(--text); text-decoration: none; font-size: 14px; }
.site-header nav { display: flex; gap: 22px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 12px; letter-spacing: .08em; }
.brand-mark {
  display: grid; place-items: center; width: 34px; height: 34px;
  color: #08110d; background: var(--green); font-weight: 900;
}

main { width: min(1500px, calc(100% - 32px)); margin: 0 auto 80px; }
.hero { padding: clamp(56px, 8vw, 112px) clamp(4px, 3vw, 42px) 52px; }
.eyebrow, .panel-label, .phase { margin: 0; color: var(--green); font-size: 13px; font-weight: 800; letter-spacing: .16em; }
.hero h1 { margin: 14px 0 18px; max-width: 900px; font-size: clamp(44px, 7vw, 94px); line-height: .98; letter-spacing: -.055em; }
.hero h1 em { color: var(--green); font-style: normal; }
.hero > p:last-child { max-width: 760px; margin: 0; color: var(--muted); font-size: clamp(17px, 2vw, 21px); }

.lab { border: 1px solid var(--line); background: var(--panel); box-shadow: 0 28px 70px rgba(0,0,0,.3); }
.toolbar { display: flex; align-items: center; gap: 18px; padding: 16px; border-bottom: 1px solid var(--line); flex-wrap: wrap; }
.scenario-tabs { display: flex; gap: 8px; flex-wrap: wrap; }
.scenario-tab, #apply-network, .control-buttons button {
  color: var(--text); background: #17201e; border: 1px solid #34423f; padding: 8px 14px; cursor: pointer;
}
.scenario-tab:hover, .scenario-tab:focus-visible, #apply-network:hover, .control-buttons button:hover { border-color: var(--green); }
.scenario-tab.is-active { color: #07110c; background: var(--green); border-color: var(--green); font-weight: 800; }
.network-fields { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-left: auto; }
.network-fields label, .progress label { color: var(--muted); font-size: 13px; }
.network-fields input, .progress input {
  width: 64px; min-height: 38px; margin: 0 5px; padding: 4px 7px;
  color: var(--text); background: #0c1110; border: 1px solid #3b4946;
}
.step-readout { display: flex; flex-direction: column; min-width: 72px; color: var(--muted); font-size: 12px; }
.step-readout strong { color: var(--text); font-size: 17px; }

.lab-grid { display: grid; grid-template-columns: minmax(0, 1.45fr) minmax(280px, .75fr) minmax(300px, .8fr); }
.trace-panel, .explain-panel, .inspect-panel { min-width: 0; padding: 22px; }
.trace-panel, .explain-panel { border-right: 1px solid var(--line); }
.panel-head { display: flex; justify-content: space-between; gap: 18px; align-items: end; margin-bottom: 15px; }
.panel-head h2, .explain-panel h2 { margin: 4px 0 0; font-size: 22px; }
.panel-head > p { margin: 0; color: var(--muted); font-size: 13px; text-align: right; }
#trajectory { display: block; width: 100%; min-height: 320px; border: 1px solid var(--line); background: #0d1211; }
.prediction-line, .authority-line { fill: none; stroke-width: 4; stroke-linejoin: round; }
.prediction-line { stroke: var(--blue); }
.authority-line { stroke: var(--green); }
.prediction-point { fill: var(--blue); }
.authority-point { fill: var(--green); }
.future-point { opacity: .18; }
.current-point { stroke: #fff; stroke-width: 3; }
.error-link { stroke: var(--red); stroke-width: 3; stroke-dasharray: 7 5; }
.tick-label { fill: #899894; font-size: 12px; }
.legend { display: flex; gap: 20px; margin: 12px 0 18px; color: var(--muted); font-size: 13px; flex-wrap: wrap; }
.legend i { display: inline-block; width: 10px; height: 10px; margin-right: 7px; border-radius: 50%; }
.prediction-dot { background: var(--blue); }
.authority-dot { background: var(--green); }
.error-dot { background: var(--red); }

.packet-strip { border-top: 1px solid var(--line); padding-top: 14px; }
.strip-head { display: flex; justify-content: space-between; color: var(--muted); font-size: 12px; letter-spacing: .08em; }
#packet-list { display: flex; gap: 7px; margin: 10px 0 0; padding: 0; list-style: none; overflow-x: auto; }
#packet-list li { min-width: 54px; padding: 7px 8px; border: 1px solid #35413f; text-align: center; color: var(--muted); font-size: 12px; }
#packet-list li.delivered { border-color: var(--green); color: var(--green); }
#packet-list li.transit { border-color: var(--amber); color: var(--amber); }
#packet-list li.lost { border-color: var(--red); color: var(--red); text-decoration: line-through; }

.phase { margin-top: 4px; }
.explain-panel > p:not(.panel-label):not(.phase) { color: var(--muted); }
.change-box, .why-box, .queue-card { margin-top: 18px; padding: 15px; border: 1px solid var(--line); background: var(--panel-2); }
.change-box > span, .why-box > span, .queue-card > span { color: var(--amber); font-size: 12px; font-weight: 800; letter-spacing: .12em; }
.why-box > span { color: var(--green); }
.change-box p, .why-box p, .queue-card p { margin: 7px 0 0; font-size: 14px; }
.tick-chips { display: flex; gap: 7px; min-height: 35px; margin-top: 10px; flex-wrap: wrap; }
.tick-chips i { display: grid; place-items: center; min-width: 34px; height: 31px; padding: 0 8px; color: var(--blue); border: 1px solid #426d91; background: #101a22; font-size: 12px; font-style: normal; }

.counter-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 9px; }
.counter-grid > div { padding: 12px; border: 1px solid var(--line); background: #0e1413; }
.counter-grid span, .counter-grid small { display: block; color: var(--muted); font-size: 12px; }
.counter-grid strong { display: block; margin: 4px 0; color: var(--text); font-size: 23px; }
.state-list { margin: 14px 0; border: 1px solid var(--line); }
.state-list div { display: flex; justify-content: space-between; gap: 15px; padding: 9px 12px; border-bottom: 1px solid var(--line); font-size: 13px; }
.state-list div:last-child { border-bottom: 0; }
.state-list dt { color: var(--muted); }
.state-list dd { margin: 0; color: var(--text); text-align: right; }
.code-panel { border: 1px solid var(--line); background: #090d0c; }
.code-head { display: flex; justify-content: space-between; padding: 10px 12px; border-bottom: 1px solid var(--line); color: var(--muted); font-size: 12px; letter-spacing: .1em; }
.code-head strong { color: var(--green); }
#code-lines { margin: 0; padding: 12px 12px 12px 46px; overflow-x: auto; font: 13px/1.65 "Cascadia Code", Consolas, monospace; white-space: pre; }
#code-lines li { padding-left: 8px; color: #b8c6c2; }
#code-lines li.is-active { color: #fff; background: rgba(99,214,154,.12); }

.controls { display: flex; justify-content: space-between; gap: 18px; padding: 16px; border-top: 1px solid var(--line); flex-wrap: wrap; }
.progress { display: flex; align-items: center; gap: 15px; flex-wrap: wrap; }
.step-dots { display: flex; gap: 6px; }
.step-dots button { width: 12px; height: 12px; min-height: 12px; padding: 0; border: 1px solid #5c6c68; border-radius: 50%; background: transparent; cursor: pointer; }
.step-dots button.is-active { background: var(--green); border-color: var(--green); }
#speed-message { color: var(--muted); font-size: 12px; }
.control-buttons { display: flex; gap: 8px; flex-wrap: wrap; }
.control-buttons .primary-button { color: #06100b; background: var(--green); border-color: var(--green); font-weight: 800; }
.keyboard-hint { margin: 0; padding: 0 16px 16px; color: var(--muted); font-size: 12px; }

.concept-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; margin-top: 32px; background: var(--line); border: 1px solid var(--line); }
.concept-grid article { padding: 24px; background: var(--panel); }
.concept-grid span { color: var(--green); font-size: 12px; }
.concept-grid h2 { margin: 7px 0; font-size: 19px; }
.concept-grid p { margin: 0; color: var(--muted); font-size: 14px; }

@media (max-width: 1120px) {
  .lab-grid { grid-template-columns: 1fr 1fr; }
  .trace-panel { grid-column: 1 / -1; border-right: 0; border-bottom: 1px solid var(--line); }
}

@media (max-width: 720px) {
  main { width: min(100% - 20px, 1500px); }
  .site-header, .controls, .panel-head { align-items: flex-start; }
  .site-header { flex-direction: column; }
  .hero h1 { font-size: 46px; }
  .lab-grid { display: block; }
  .trace-panel, .explain-panel { border-right: 0; border-bottom: 1px solid var(--line); }
  .network-fields { margin-left: 0; }
  .concept-grid { grid-template-columns: 1fr; }
  #trajectory { min-height: 240px; }
}

@media (prefers-reduced-motion: reduce) {
  * { scroll-behavior: auto !important; transition: none !important; }
}