:root {
  color-scheme: dark;
  --ink: #f4f7fb;
  --muted: #aeb8c8;
  --line: rgba(255, 255, 255, 0.14);
  --panel: rgba(13, 20, 34, 0.82);
  --gold: #f5b84b;
  --blue: #70b8ff;
  --violet: #8e86ff;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 12% 18%, rgba(245, 184, 75, 0.16), transparent 28%),
    radial-gradient(circle at 85% 16%, rgba(112, 184, 255, 0.18), transparent 32%),
    #05070d;
}

button,
a,
input {
  font: inherit;
}

.app-shell {
  width: min(1480px, calc(100% - 28px));
  margin: 0 auto;
  padding: 22px 0 34px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding-bottom: 18px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: var(--ink);
  font-weight: 850;
  text-decoration: none;
}

.brand-mark {
  width: 42px;
  height: 42px;
  display: block;
  filter: drop-shadow(0 12px 22px rgba(0, 0, 0, 0.3));
}

.mode-tabs {
  display: flex;
  gap: 8px;
  padding: 5px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.08);
}

.mode-tab {
  min-height: 40px;
  border: 0;
  border-radius: 7px;
  background: transparent;
  color: var(--muted);
  font-weight: 850;
  padding: 0 13px;
  cursor: pointer;
}

.mode-tab.is-active {
  color: #111820;
  background: var(--gold);
}

.workspace {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 390px;
  gap: 18px;
}

.sim-panel,
.control-panel {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.34);
}

.sim-panel {
  min-height: 760px;
  overflow: hidden;
}

#eclipseCanvas {
  display: block;
  width: 100%;
  height: 700px;
}

.timeline {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  align-items: center;
  gap: 14px;
  padding: 16px 18px 18px;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 820;
}

.timeline span:nth-child(2) {
  text-align: center;
}

.timeline span:nth-child(3) {
  text-align: right;
}

.timeline input {
  grid-column: 1 / -1;
  width: 100%;
}

input[type="range"] {
  accent-color: var(--gold);
}

.control-panel {
  padding: 20px;
}

.hero-copy span {
  color: var(--gold);
  font-size: 0.78rem;
  font-weight: 950;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero-copy h1 {
  margin: 10px 0 12px;
  font-size: clamp(2.25rem, 4.5vw, 4.25rem);
  line-height: 0.94;
  letter-spacing: 0;
}

.hero-copy p,
.lesson-card p,
.fact-list li {
  color: var(--muted);
  line-height: 1.55;
}

.readout-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 18px;
}

.readout-grid article,
.lesson-card,
.fact-list,
.controls,
.legend {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.06);
}

.readout-grid article {
  min-height: 96px;
  padding: 14px;
}

.readout-grid span,
.controls label > span {
  display: block;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 900;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.readout-grid strong {
  display: block;
  margin-top: 10px;
  color: #ffffff;
  font-size: 1.18rem;
}

.controls {
  display: grid;
  gap: 15px;
  margin-top: 12px;
  padding: 15px;
}

.controls input[type="range"] {
  width: 100%;
  margin-top: 10px;
}

.toggle {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 800;
}

.toggle span {
  text-transform: none;
  letter-spacing: 0;
  font-size: 0.95rem;
}

.legend {
  display: grid;
  gap: 10px;
  margin-top: 12px;
  padding: 15px;
}

.legend div {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--muted);
  font-weight: 760;
}

.legend i {
  width: 34px;
  height: 12px;
  border-radius: 999px;
}

.legend .umbra {
  background: rgba(4, 7, 12, 0.92);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.18);
}

.legend .penumbra {
  background: rgba(90, 109, 141, 0.68);
}

.legend .orbit {
  border: 2px dashed var(--blue);
}

.lesson-card,
.fact-list {
  margin-top: 12px;
  padding: 16px;
}

.lesson-card h2,
.fact-list h2 {
  margin: 0 0 9px;
  font-size: 1.18rem;
}

.lesson-card p,
.fact-list ul {
  margin: 0;
}

.fact-list ul {
  padding-left: 20px;
}

.fact-list li + li {
  margin-top: 8px;
}

@media (max-width: 1040px) {
  .workspace {
    grid-template-columns: 1fr;
  }

  .sim-panel {
    min-height: 620px;
  }

  #eclipseCanvas {
    height: 560px;
  }
}

@media (max-width: 640px) {
  .app-shell {
    width: min(100% - 20px, 1480px);
    padding-top: 14px;
  }

  .topbar,
  .mode-tabs {
    align-items: stretch;
    flex-direction: column;
  }

  .sim-panel {
    min-height: 500px;
  }

  #eclipseCanvas {
    height: 430px;
  }

  .timeline,
  .readout-grid {
    grid-template-columns: 1fr;
  }
}