/* =====================================================================
   Solar System Simulation – Global Styles
   ===================================================================== */

:root {
  --bg-dark: #000000;
  --bg-panel: rgba(10, 20, 40, 0.85);
  --accent: #4fc3f7;
  --accent2: #ffb300;
  --text: #e8eaf6;
  --text-muted: #90a4ae;
  --border: rgba(79, 195, 247, 0.25);
  --radius: 8px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html,
body {
  height: 100%;
  font-family: "Segoe UI", system-ui, sans-serif;
  background: var(--bg-dark);
  color: var(--text);
  line-height: 1.6;
}

/* ── Navigation ──────────────────────────────────────────────────── */
nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  background: rgba(0, 0, 0, 0.92);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(8px);
}

nav .brand {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--accent2);
  text-decoration: none;
  margin-right: auto;
  letter-spacing: 0.05em;
}

nav a {
  color: var(--text-muted);
  text-decoration: none;
  padding: 0.35rem 0.8rem;
  border-radius: var(--radius);
  font-size: 0.9rem;
  transition: background 0.2s, color 0.2s;
}

nav a:hover,
nav a.active {
  background: var(--border);
  color: var(--accent);
}

/* ── Page wrapper ────────────────────────────────────────────────── */
.page {
  padding-top: 52px; /* nav height */
}

/* ── Simulation page ─────────────────────────────────────────────── */
#canvas-container {
  position: fixed;
  top: 52px;
  left: 0;
  right: 0;
  bottom: 0;
  background: #000;
}

#canvas-container canvas {
  display: block;
  width: 100% !important;
  height: 100% !important;
  background: #000;
}

/* Labels overlay (HTML) */
#labels-layer {
  position: fixed;
  top: 52px;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 40;
  pointer-events: none;
}

.planet-label {
  position: absolute;
  transform: translate(-50%, -100%);
  color: var(--text);
  font-size: 14px;
  font-weight: 700;
  white-space: nowrap;
  user-select: none;
}

/* Control panel */
#controls {
  position: fixed;
  top: 62px;
  right: 14px;
  z-index: 50;
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.9rem 1.1rem;
  min-width: 230px;
  backdrop-filter: blur(10px);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.5);
}

#controls h3 {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  margin-bottom: 0.7rem;
}

#controls label {
  display: block;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.2rem;
  margin-top: 0.6rem;
}

#controls input[type="datetime-local"],
#controls input[type="range"] {
  width: 100%;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text);
  padding: 0.3rem 0.5rem;
  font-size: 0.82rem;
}

#controls input[type="datetime-local"]:focus {
  outline: none;
  border-color: var(--accent);
}

#controls input[type="range"] {
  padding: 0;
  accent-color: var(--accent);
  cursor: pointer;
}

#controls .btn-row {
  display: flex;
  gap: 0.4rem;
  margin-top: 0.8rem;
}

#controls button {
  flex: 1;
  padding: 0.35rem 0.5rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: rgba(79, 195, 247, 0.1);
  color: var(--accent);
  font-size: 0.8rem;
  cursor: pointer;
  transition: background 0.2s;
}

#controls button:hover {
  background: rgba(79, 195, 247, 0.22);
}

#controls button.active {
  background: rgba(79, 195, 247, 0.3);
  border-color: var(--accent);
}

/* Planet info tooltip */
#planet-info {
  position: fixed;
  bottom: 18px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.6rem 1.2rem;
  font-size: 0.85rem;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.3s;
  white-space: nowrap;
  z-index: 60;
}

#planet-info.visible {
  opacity: 1;
}

/* Speed indicator */
#speed-label {
  font-size: 0.75rem;
  color: var(--accent);
  text-align: right;
}

/* ── Content pages (history / math) ─────────────────────────────── */
.content-page {
  max-width: 860px;
  margin: 0 auto;
  padding: 2rem 1.5rem 4rem;
}

.content-page h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent2);
  margin-bottom: 0.4rem;
}

.content-page .subtitle {
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 1rem;
}

.content-page h2 {
  font-size: 1.35rem;
  color: var(--accent);
  margin-top: 2.5rem;
  margin-bottom: 0.6rem;
}

.content-page h3 {
  font-size: 1.05rem;
  color: var(--text);
  margin-top: 1.4rem;
  margin-bottom: 0.4rem;
  font-weight: 600;
}

.content-page p {
  color: var(--text-muted);
  margin-bottom: 0.8rem;
}

.content-page ul,
.content-page ol {
  margin-left: 1.4rem;
  margin-bottom: 0.8rem;
  color: var(--text-muted);
}

.content-page li {
  margin-bottom: 0.3rem;
}

.content-page .timeline {
  border-left: 2px solid var(--border);
  padding-left: 1.4rem;
  margin-top: 1rem;
}

.content-page .timeline-item {
  position: relative;
  margin-bottom: 1.6rem;
}

.content-page .timeline-item::before {
  content: "";
  position: absolute;
  left: -1.65rem;
  top: 0.45rem;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg-dark);
}

.content-page .timeline-item .year {
  font-size: 0.8rem;
  color: var(--accent2);
  font-weight: 700;
  letter-spacing: 0.06em;
  margin-bottom: 0.2rem;
}

/* Math blocks */
.math-block {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  margin: 1rem 0;
  font-family: "Courier New", monospace;
  font-size: 0.9rem;
  color: var(--accent);
  overflow-x: auto;
}

.math-block .comment {
  color: var(--text-muted);
}

.note-box {
  background: rgba(79, 195, 247, 0.07);
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 0.7rem 1rem;
  margin: 1rem 0;
  font-size: 0.9rem;
  color: var(--text);
}

/* Responsive */
@media (max-width: 600px) {
  #controls {
    right: 8px;
    top: 60px;
    min-width: 200px;
  }
  .content-page {
    padding: 1.2rem 1rem 3rem;
  }
}