:root {
  --color-bg: #0a0a12;
  --color-surface: #11111f;
  --color-border: #1e1e36;
  --color-text: #e0e0f0;
  --color-text-muted: #6a6a9a;
  --color-accent: #4a90e2;
  --color-accent-dim: #2a5090;

  --font-sans: system-ui, -apple-system, sans-serif;
  --font-mono: ui-monospace, "Cascadia Code", "Fira Code", monospace;

  --header-height: 56px;
  --panel-width: 300px;
  --panel-width-sm: 260px;
}

body {
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  font-size: 14px;
  line-height: 1.5;
  height: 100%;
  overflow: hidden;
}

#app {
  display: flex;
  flex-direction: column;
  height: 100%;
}

/* ── Header ── */

#header {
  flex: 0 0 var(--header-height);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 20px;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-surface);
}

#header h1 {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--color-text);
}

#header .tagline {
  font-size: 12px;
  color: var(--color-text-muted);
  flex: 1;
}

.btn-share {
  height: 28px;
  padding: 0 10px;
  background: transparent;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-size: 12px;
  cursor: pointer;
  white-space: nowrap;
  transition: color 0.15s, border-color 0.15s;
}

.btn-share:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
}

/* ── Main layout ── */

#main {
  flex: 1 1 0;
  display: flex;
  overflow: hidden;
}

/* ── Canvas ── */

#canvas-container {
  flex: 1 1 0;
  position: relative;
  overflow: hidden;
  background: var(--color-bg);
}

#solar-system {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  cursor: crosshair;
}

/* ── Control panel ── */

#control-panel {
  flex: 0 0 var(--panel-width);
  display: flex;
  flex-direction: column;
  gap: 0;
  border-left: 1px solid var(--color-border);
  background: var(--color-surface);
  overflow-y: auto;
}

.placeholder {
  padding: 20px;
  color: var(--color-text-muted);
  font-style: italic;
}

/* ── Zoom controls overlay ── */

#zoom-controls {
  position: absolute;
  bottom: 16px;
  right: 16px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  z-index: 10;
}

.btn-zoom {
  width: 32px;
  height: 32px;
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s, border-color 0.15s;
  user-select: none;
}

.btn-zoom:hover {
  background: var(--color-border);
  border-color: var(--color-accent);
}

/* ── Panel sections ── */

.panel-section {
  padding: 16px;
  border-bottom: 1px solid var(--color-border);
}

.panel-section--muted {
  flex: 1 1 0;
}

.panel-heading {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: 12px;
}

/* ── Mission planner fields ── */

.field-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.field-row--col {
  flex-direction: column;
  align-items: stretch;
  gap: 4px;
}

.field-row-top {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}

.field-label {
  font-size: 12px;
  color: var(--color-text-muted);
  flex: 0 0 36px;
}

.field-value {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-accent);
}

.field-select {
  flex: 1 1 0;
  min-width: 0;
  background: var(--color-bg);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 5px 8px;
  font-size: 13px;
  cursor: pointer;
  appearance: auto;
}

.field-select:focus {
  outline: none;
  border-color: var(--color-accent);
}

.field-range {
  width: 100%;
  accent-color: var(--color-accent);
  cursor: pointer;
}

.field-range-labels {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--color-text-muted);
  margin-top: 2px;
}

.field-range-label--comfort {
  color: #70c070;
}

/* ── Animation controls ── */

.anim-controls {
  display: flex;
  align-items: center;
  gap: 6px;
}

.btn-anim {
  width: 32px;
  height: 28px;
  background: var(--color-bg);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-size: 12px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s, border-color 0.15s;
}

.btn-anim:hover:not(:disabled) {
  background: var(--color-border);
  border-color: var(--color-accent);
}

.btn-anim:disabled {
  opacity: 0.35;
  cursor: default;
}

.anim-elapsed {
  margin-left: 4px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-accent);
}

.anim-speed {
  display: flex;
  gap: 4px;
  margin-top: 8px;
}

.btn-speed {
  flex: 1;
  height: 24px;
  background: var(--color-bg);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-size: 11px;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.btn-speed:hover:not(.btn-speed--active) {
  background: var(--color-border);
  border-color: var(--color-accent);
}

.btn-speed--active {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: #000;
}

/* ── Scrub bar ── */

.anim-scrub {
  -webkit-appearance: none;
  appearance: none;
  display: block;
  width: 100%;
  height: 4px;
  border-radius: 2px;
  /* Filled portion driven by --scrub-pct (updated via JS) */
  background: linear-gradient(
    to right,
    var(--color-accent) var(--scrub-pct, 0%),
    var(--color-border) var(--scrub-pct, 0%)
  );
  cursor: pointer;
  margin-top: 10px;
  outline: none;
  border: none;
}

.anim-scrub::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-accent);
  cursor: pointer;
  transition: transform 0.1s;
}

.anim-scrub::-webkit-slider-thumb:hover {
  transform: scale(1.3);
}

.anim-scrub::-moz-range-thumb {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-accent);
  border: none;
  cursor: pointer;
}

/* ── Mission info panel ── */

.info-route {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
  flex-wrap: wrap;
}

.info-arrow {
  color: var(--color-text-muted);
}

.info-divider {
  height: 1px;
  background: var(--color-border);
  margin: 8px 0;
}

.info-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 4px;
  font-size: 12px;
}

.info-key {
  color: var(--color-text-muted);
  flex-shrink: 0;
  padding-right: 8px;
}

.info-val {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-text);
  text-align: right;
}

.info-val--accent {
  color: var(--color-accent);
}

.info-val--ship {
  color: #a0e8b0;
}

.info-badge {
  font-size: 10px;
  font-weight: 600;
  padding: 1px 5px;
  border-radius: 3px;
  letter-spacing: 0.02em;
}

.info-badge--warn {
  background: #3a2a00;
  color: #f0c040;
  border: 1px solid #604800;
}

.info-badge--detour {
  background: #2a1500;
  color: #ff9040;
  border: 1px solid #6a3000;
}

.info-comfort-warn {
  font-size: 11px;
  color: #f0a030;
  background: #2a1a00;
  border: 1px solid #5a3800;
  border-radius: 4px;
  padding: 5px 8px;
  margin-bottom: 8px;
}

/* ── Relativity panel ── */

.info-empty {
  color: var(--color-text-muted);
  font-style: italic;
  font-size: 13px;
}

.rel-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: 10px;
}

.rel-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 5px;
  font-size: 13px;
}

.rel-row--dim {
  opacity: 0.65;
}

.rel-key {
  color: var(--color-text-muted);
}

.rel-val {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-text);
}

.rel-val--ship {
  color: #a0e8b0;
}

.rel-bar-wrap {
  position: relative;
  height: 6px;
  border-radius: 3px;
  background: var(--color-border);
  margin: 10px 0 4px;
  overflow: hidden;
}

.rel-bar {
  position: absolute;
  inset: 0 auto 0 0;
  background: linear-gradient(90deg, var(--color-accent-dim), var(--color-accent));
  border-radius: 3px;
  transition: width 0.3s ease;
}

.rel-bar-labels {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--color-text-muted);
  margin-bottom: 10px;
}

.rel-bar-label-pct {
  font-family: var(--font-mono);
  color: var(--color-accent);
}

/* ── Date picker ── */

.date-input-row {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-bottom: 10px;
}

#date-input {
  flex: 1 1 0;
  min-width: 0;
  background: var(--color-bg);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 5px 8px;
  font-size: 13px;
  color-scheme: dark;
}

#date-input:focus {
  outline: none;
  border-color: var(--color-accent);
}

.date-step-row {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 4px;
}

.btn-step {
  background: var(--color-bg);
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 4px 0;
  font-size: 11px;
  font-weight: 600;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.btn-step:hover {
  color: var(--color-text);
  border-color: var(--color-accent);
}

.btn-ghost {
  background: transparent;
  color: var(--color-accent);
  border: 1px solid var(--color-accent-dim);
  border-radius: 4px;
  padding: 5px 10px;
  font-size: 12px;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.15s;
}

.btn-ghost:hover {
  background: var(--color-accent-dim);
  color: var(--color-text);
}

/* ── About modal ── */

.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: rgba(4, 4, 12, 0.65);
  backdrop-filter: blur(2px);
}

.modal-overlay[hidden] {
  display: none;
}

.modal {
  position: relative;
  width: 100%;
  max-width: 560px;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 12px 48px rgba(0, 0, 0, 0.6);
}

.modal-starfield {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.modal-header {
  position: relative;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  border-bottom: 1px solid var(--color-border);
}

.modal-logo {
  width: 48px;
  height: 48px;
  flex-shrink: 0;
}

.modal-header h2 {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.modal-subtitle {
  font-size: 12px;
  color: var(--color-text-muted);
}

.modal-close {
  margin-left: auto;
  width: 28px;
  height: 28px;
  background: transparent;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.modal-close:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
}

.modal-body {
  position: relative;
  overflow-y: auto;
  padding: 16px 20px 20px;
  font-size: 13px;
}

.modal-body h3 {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin: 16px 0 6px;
}

.modal-body h3:first-child {
  margin-top: 0;
}

.modal-body p {
  color: var(--color-text);
  margin-bottom: 8px;
}

.modal-body ul {
  list-style: disc;
  padding-left: 20px;
  margin-bottom: 8px;
}

.modal-body li {
  margin-bottom: 4px;
}

.modal-topic-link {
  color: var(--color-accent);
  text-decoration: underline dotted;
  text-underline-offset: 2px;
}

.modal-topic-link:hover {
  text-decoration-style: solid;
}

.modal-back {
  display: inline-block;
  color: var(--color-text-muted);
  font-size: 12px;
  text-decoration: none;
  margin-bottom: 12px;
  transition: color 0.15s;
}

.modal-back:hover {
  color: var(--color-accent);
}

.modal-footnote {
  font-size: 11px;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
  padding-top: 10px;
  margin-top: 14px;
}

/* ── Responsive ── */

@media (max-width: 640px) {
  body {
    overflow: auto;
  }

  #app {
    height: auto;
    min-height: 100%;
  }

  #main {
    flex-direction: column;
    overflow: visible;
  }

  #canvas-container {
    flex: none;
    height: 60vw;
    min-height: 280px;
    position: relative;
  }

  #control-panel {
    flex: none;
    width: 100%;
    border-left: none;
    border-top: 1px solid var(--color-border);
  }
}