/* ============================================================
   World Calendar Explorer — design system.
   Reference: observatory instruments, antique scientific atlases,
   mechanical clocks, NASA/Smithsonian exhibit design. Two themes:
   "Observatory" (dark) and "Atlas" (light parchment).
   ============================================================ */
:root {
  --ink: #1c1a14;
  --ink-dim: #5a5644;
  --paper: #f4efe1;
  --paper-alt: #ece4cf;
  --panel: #fffdf7;
  --line: #c9bd9a;
  --line-strong: #1c1a14;
  --brass: #9c7a2e;
  --brass-bright: #b8923f;
  --accent: #8a2c1e;
  --accent-2: #1f4d6b;
  --good: #3a6b35;
  --shadow: rgba(28, 26, 20, 0.18);

  --font-display: "Spectral", Georgia, serif;
  --font-body: "Inter", -apple-system, sans-serif;
  --font-mono: "IBM Plex Mono", monospace;

  --radius: 3px;
  --max-width: 1240px;
}

:root[data-theme="dark"] {
  --ink: #ece4cf;
  --ink-dim: #a99f80;
  --paper: #14171f;
  --paper-alt: #1b1f29;
  --panel: #1a1e27;
  --line: #333a49;
  --line-strong: #ece4cf;
  --brass: #c9a24b;
  --brass-bright: #e6c878;
  --accent: #d16a52;
  --accent-2: #6fa8c9;
  --good: #7bbf72;
  --shadow: rgba(0, 0, 0, 0.5);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --ink: #ece4cf;
    --ink-dim: #a99f80;
    --paper: #14171f;
    --paper-alt: #1b1f29;
    --panel: #1a1e27;
    --line: #333a49;
    --line-strong: #ece4cf;
    --brass: #c9a24b;
    --brass-bright: #e6c878;
    --accent: #d16a52;
    --accent-2: #6fa8c9;
    --good: #7bbf72;
    --shadow: rgba(0, 0, 0, 0.5);
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  background-image:
    radial-gradient(ellipse at top, color-mix(in srgb, var(--brass) 6%, transparent), transparent 60%);
  color: var(--ink);
  font-family: var(--font-body);
  line-height: 1.5;
  transition: background 0.2s ease, color 0.2s ease;
}

.wrap {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- Top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--line);
}

.topbar-inner {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 12px 20px;
  max-width: var(--max-width);
  margin: 0 auto;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--ink);
  text-decoration: none;
  white-space: nowrap;
}

.brand .glyph {
  width: 28px;
  height: 28px;
  flex-shrink: 0;
}

.section-nav {
  display: flex;
  gap: 2px;
  overflow-x: auto;
  scrollbar-width: none;
  flex: 1;
}
.section-nav::-webkit-scrollbar { display: none; }

.section-nav a {
  color: var(--ink-dim);
  text-decoration: none;
  font-size: 0.78rem;
  letter-spacing: 0.03em;
  padding: 8px 10px;
  white-space: nowrap;
  border-bottom: 2px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.section-nav a:hover,
.section-nav a.active {
  color: var(--ink);
  border-color: var(--brass);
}

.theme-toggle {
  background: transparent;
  border: 1px solid var(--line);
  color: var(--ink);
  border-radius: var(--radius);
  padding: 6px 10px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  cursor: pointer;
  white-space: nowrap;
}
.theme-toggle:hover { border-color: var(--brass); }

/* ---------- Sections ---------- */
main { padding-bottom: 80px; }

section {
  padding: 56px 0 24px;
  border-bottom: 1px solid var(--line);
}
section:last-child { border-bottom: none; }

.section-head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 22px;
}

.section-num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--brass);
  border: 1px solid var(--brass);
  border-radius: 50%;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 600;
  margin: 0;
  color: var(--ink);
}

h1 { font-size: 2.1rem; }
h2 { font-size: 1.5rem; letter-spacing: 0.01em; }
h3 { font-size: 1.05rem; }

.section-sub {
  color: var(--ink-dim);
  font-size: 0.92rem;
  max-width: 68ch;
  margin: 0 0 24px;
}

/* ---------- Hero / dashboard ---------- */
.hero {
  padding: 40px 0 20px;
  text-align: center;
}
.hero .eyebrow {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--brass);
  margin-bottom: 10px;
}
.hero h1 { font-size: clamp(2rem, 5vw, 3.1rem); }
.hero p { color: var(--ink-dim); max-width: 60ch; margin: 12px auto 0; }

.dash-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 14px;
  margin-top: 32px;
}

.dash-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 18px;
  box-shadow: 0 2px 8px var(--shadow);
}
.dash-card .label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--brass);
  margin-bottom: 8px;
}
.dash-card .value {
  font-family: var(--font-mono);
  font-size: 1.25rem;
  color: var(--ink);
  word-break: break-word;
}
.dash-card .sub {
  font-size: 0.78rem;
  color: var(--ink-dim);
  margin-top: 4px;
}

/* ---------- Card / panel ---------- */
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: 0 2px 8px var(--shadow);
}

/* ---------- Converter ---------- */
.converter {
  display: grid;
  grid-template-columns: minmax(220px, 320px) 1fr;
  gap: 24px;
  align-items: start;
}
@media (max-width: 760px) {
  .converter { grid-template-columns: 1fr; }
}

.converter-input label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--brass);
  margin: 14px 0 6px;
}
.converter-input label:first-child { margin-top: 0; }

.converter-input input[type="date"],
.converter-input input[type="text"] {
  width: 100%;
  background: var(--paper-alt);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--ink);
  padding: 9px 10px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
}

.btn {
  background: var(--ink);
  color: var(--paper);
  border: 1px solid var(--ink);
  border-radius: var(--radius);
  padding: 9px 16px;
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.82rem;
  cursor: pointer;
  transition: opacity 0.15s ease;
}
.btn:hover { opacity: 0.82; }
.btn.secondary {
  background: transparent;
  color: var(--ink);
  border-color: var(--line);
}
.btn-row { display: flex; gap: 8px; margin-top: 14px; flex-wrap: wrap; }

.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 10px;
}
.result-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 12px 14px;
  background: var(--paper-alt);
}
.result-card .cal-name {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--brass);
}
.result-card .cal-value {
  font-size: 0.95rem;
  margin-top: 4px;
  color: var(--ink);
}
.result-card .cal-note {
  font-size: 0.74rem;
  color: var(--ink-dim);
  margin-top: 4px;
}

/* ---------- Table ---------- */
.table-scroll { overflow-x: auto; }
table.calendar-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.86rem;
}
table.calendar-table caption { display: none; }
table.calendar-table th,
table.calendar-table td {
  text-align: left;
  padding: 9px 12px;
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}
table.calendar-table th {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--brass);
  border-bottom: 2px solid var(--line-strong);
  position: sticky;
  top: 0;
  background: var(--panel);
}
table.calendar-table tbody tr:hover { background: var(--paper-alt); }
table.calendar-table td.category {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--ink-dim);
}

/* ---------- Filter chips ---------- */
.chip-row { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 16px; }
.chip {
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 5px 12px;
  font-size: 0.74rem;
  font-family: var(--font-mono);
  cursor: pointer;
  color: var(--ink-dim);
  background: transparent;
}
.chip.active { background: var(--brass); border-color: var(--brass); color: var(--panel); }

/* ---------- Encyclopedia ---------- */
.encyclopedia-list {
  display: grid;
  gap: 10px;
}
.encyclo-entry {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}
.encyclo-entry summary {
  cursor: pointer;
  padding: 14px 18px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.02rem;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}
.encyclo-entry summary::-webkit-details-marker { display: none; }
.encyclo-entry summary .tag {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--brass);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 400;
}
.encyclo-body {
  padding: 0 18px 18px;
  display: grid;
  gap: 10px;
}
.encyclo-body dl {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 6px 14px;
  margin: 0;
  font-size: 0.88rem;
}
.encyclo-body dt {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--brass);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.encyclo-body dd { margin: 0; color: var(--ink); }
.encyclo-body p { margin: 0; font-size: 0.9rem; }

/* ---------- Timeline ---------- */
.timeline {
  position: relative;
  padding-left: 28px;
  border-left: 2px solid var(--line);
}
.timeline-item {
  position: relative;
  padding-bottom: 26px;
}
.timeline-item::before {
  content: "";
  position: absolute;
  left: -34px;
  top: 4px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--brass);
  border: 2px solid var(--paper);
  box-shadow: 0 0 0 1px var(--brass);
}
.timeline-item .t-year {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--brass);
  font-weight: 600;
}
.timeline-item h3 { margin: 3px 0 4px; font-size: 1rem; }
.timeline-item p { margin: 0; font-size: 0.88rem; color: var(--ink-dim); max-width: 62ch; }

/* ---------- Astronomy diagrams ---------- */
.astro-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
}
.astro-card svg { width: 100%; height: auto; display: block; }
.astro-card .astro-caption {
  font-size: 0.84rem;
  color: var(--ink-dim);
  margin-top: 10px;
}
.astro-controls { display: flex; align-items: center; gap: 10px; margin-top: 10px; }
.astro-controls input[type="range"] { flex: 1; }
.astro-readout { font-family: var(--font-mono); font-size: 0.8rem; color: var(--brass); min-width: 90px; text-align: right; }

/* ---------- Comparison ---------- */
.compare-table td.bar-cell { min-width: 160px; }
.bar-track {
  height: 8px;
  background: var(--paper-alt);
  border: 1px solid var(--line);
  border-radius: 4px;
  overflow: hidden;
}
.bar-fill { height: 100%; background: var(--accent); }

/* ---------- Math lab ---------- */
.formula-block {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  background: var(--paper-alt);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px 16px;
  overflow-x: auto;
  white-space: pre;
  line-height: 1.6;
}

/* ---------- Footer ---------- */
footer {
  text-align: center;
  padding: 30px 20px 50px;
  color: var(--ink-dim);
  font-size: 0.78rem;
}
footer a { color: var(--brass); }

/* ---------- misc ---------- */
.note {
  font-size: 0.82rem;
  color: var(--ink-dim);
  border-left: 2px solid var(--brass);
  padding-left: 10px;
  margin: 12px 0;
}
.small { font-size: 0.78rem; color: var(--ink-dim); }
a { color: var(--accent-2); }

/* ---------- Source calendar selector ---------- */
.converter-input select {
  width: 100%;
  background: var(--paper-alt);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--ink);
  padding: 9px 10px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  cursor: pointer;
}

.source-fields {
  display: grid;
  gap: 8px;
}
.source-fields .field-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.source-fields .field-group label {
  margin: 0;
}
.source-fields input[type="number"],
.source-fields select {
  width: 100%;
  background: var(--paper-alt);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--ink);
  padding: 9px 10px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
}
.source-fields input[type="number"] {
  -moz-appearance: textfield;
}
.source-fields input[type="number"]::-webkit-outer-spin-button,
.source-fields input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

/* ---------- Maya links ---------- */
.maya-link {
  color: var(--accent-2);
  text-decoration: none;
  border-bottom: 1px dotted var(--accent-2);
}
.maya-link:hover {
  border-bottom-style: solid;
}

@media (max-width: 640px) {
  .topbar-inner { flex-wrap: wrap; }
  section { padding-top: 40px; }
}