/* WANDERERS brand system: shared tokens, type, header, theme toggle, footer.
 * Day Observatory (light) and Night Observatory (dark) are the same tokens with different values.
 * Scientific imagery always sits on --viewer, which stays dark in both themes and is never recoloured. */
@import url("https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500&family=Inter:wght@400;500;600&family=Manrope:wght@700;800&family=Sora:wght@800&display=swap");

:root {
  --bg: #F6F8FB;
  --surface: #FFFFFF;
  --surface-2: #EEF2F7;
  --text: #172B45;
  --muted: #52677D;
  --accent: #2864C5;
  --accent-2: #4D8796;
  --accent-soft: rgba(40, 100, 197, .09);
  --line: #DCE4ED;
  --line-strong: #C3CFDC;
  --viewer: #081321;
  --viewer-ink: #E6EEF8;
  --viewer-muted: #9AB0C8;
  --on-accent: #FFFFFF;
  --known: #1D7A57;
  --cand: #9A5A00;
  --warn: #B3261E;
  --h2o: rgba(40, 100, 197, .13);
  --ch4: rgba(196, 120, 20, .15);
  --co: rgba(128, 72, 190, .12);
  --h2o-line: rgba(40, 100, 197, .55);
  --ch4-line: rgba(196, 120, 20, .6);
  --co-line: rgba(128, 72, 190, .5);
  --shadow: 0 1px 2px rgba(23, 43, 69, .04), 0 8px 24px -12px rgba(23, 43, 69, .12);

  --f-mark: "Sora", "Helvetica Neue", Arial, sans-serif;
  --f-display: "Manrope", "Helvetica Neue", Arial, sans-serif;
  --f-ui: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --f-mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --mono: var(--f-mono);
  --radius: 6px;
  --gutter: clamp(16px, 4vw, 48px);
  --maxw: 1320px;
  color-scheme: light;
}
:root[data-theme="dark"] {
  --bg: #0B1422;
  --surface: #152438;
  --surface-2: #1A2C43;
  --text: #F1F5FA;
  --muted: #B5C9DE;
  --accent: #8AB6EF;
  --accent-2: #7FB8C4;
  --accent-soft: rgba(138, 182, 239, .12);
  --line: #293B50;
  --line-strong: #3A5068;
  --viewer: #050B14;
  --on-accent: #0B1422;
  --known: #66D4AA;
  --cand: #F2B866;
  --warn: #FF9D92;
  --h2o: rgba(110, 170, 255, .10);
  --ch4: rgba(255, 175, 70, .09);
  --co: rgba(190, 140, 255, .09);
  --h2o-line: rgba(110, 170, 255, .6);
  --ch4-line: rgba(255, 175, 70, .6);
  --co-line: rgba(190, 140, 255, .55);
  --shadow: 0 1px 2px rgba(0, 0, 0, .2), 0 10px 30px -14px rgba(0, 0, 0, .5);
  color-scheme: dark;
}
/* No JavaScript: follow the operating system */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --bg: #0B1422; --surface: #152438; --surface-2: #1A2C43; --text: #F1F5FA; --muted: #B5C9DE;
    --accent: #8AB6EF; --accent-2: #7FB8C4; --accent-soft: rgba(138,182,239,.12); --line: #293B50; --line-strong: #3A5068;
    --viewer: #050B14; --on-accent: #0B1422; --known: #66D4AA; --cand: #F2B866; --warn: #FF9D92; color-scheme: dark;
  }
}

/* Theme change: animate colours only while switching, never on page load */
html.theme-anim, html.theme-anim *, html.theme-anim *::before, html.theme-anim *::after {
  transition: background-color .25s ease, color .25s ease, border-color .25s ease, fill .25s ease, stroke .25s ease !important;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 400 15px/1.55 var(--f-ui);
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; }
a { color: var(--accent); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.mono { font-family: var(--f-mono); }
.skip { position: absolute; left: -9999px; top: 8px; z-index: 100; background: var(--surface); padding: 8px 14px; border-radius: 4px; }
.skip:focus { left: 8px; }
.visually-hidden { position: absolute !important; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* Eyebrow / measurement labels */
.eyebrow { font: 500 .72rem/1.3 var(--f-mono); letter-spacing: .14em; text-transform: uppercase; color: var(--muted); }
.tag-chip { display: inline-flex; align-items: center; gap: 6px; font: 500 .66rem/1 var(--f-mono); letter-spacing: .1em;
  text-transform: uppercase; padding: 4px 7px; border-radius: 3px; border: 1px solid var(--line-strong); color: var(--muted); white-space: nowrap; }
.tag-chip.data { color: var(--known); border-color: color-mix(in srgb, var(--known) 45%, transparent); }
.tag-chip.ai { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 45%, transparent); }
.tag-chip.illus { color: var(--cand); border-color: color-mix(in srgb, var(--cand) 45%, transparent); }

/* ---------- Logo ---------- */
/* Orbit Epochs emblem ('ui' cut) + Sora ExtraBold wordmark. Geometry lives in app/brand/*.svg; see BRAND.md. */
.logo { display: inline-flex; align-items: center; gap: 9px; text-decoration: none; color: var(--text); }
.logo svg { width: 32px; height: 32px; flex: none; }
.logo .ink { stroke: var(--text); fill: none; }
.logo .acc { stroke: var(--accent); fill: none; }
.logo .ring { stroke: var(--accent); stroke-opacity: .75; fill: none; }
.logo .dot { fill: var(--accent); }
.logo .ink-dot { fill: var(--text); }
.wordmark { font: 800 1.3rem/1 var(--f-mark); letter-spacing: -.025em; }

/* ---------- Header ---------- */
.site-head { position: sticky; top: 0; z-index: 50; background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: saturate(140%) blur(12px); -webkit-backdrop-filter: saturate(140%) blur(12px); border-bottom: 1px solid var(--line); }
.site-head .bar { max-width: var(--maxw); margin: 0 auto; padding: 12px var(--gutter); display: flex; align-items: center; gap: 24px; }
.site-nav { display: flex; gap: 4px; margin-left: auto; align-items: center; }
.site-nav a { font: 500 .9rem/1 var(--f-ui); color: var(--muted); text-decoration: none; padding: 9px 12px; border-radius: 4px; }
.site-nav a:hover, .site-nav a[aria-current="page"] { color: var(--text); background: var(--accent-soft); }
.head-tools { display: flex; align-items: center; gap: 8px; }
.nav-toggle { display: none; }

.theme-toggle { position: relative; width: 62px; height: 32px; border-radius: 999px; border: 1px solid var(--line-strong);
  background: var(--surface); cursor: pointer; padding: 0; color: var(--text); flex: none; }
.theme-toggle .knob { position: absolute; top: 3px; left: 3px; width: 24px; height: 24px; border-radius: 50%; background: var(--accent);
  transition: transform .26s cubic-bezier(.4, 0, .2, 1); }
:root[data-theme="dark"] .theme-toggle .knob { transform: translateX(30px); }
.theme-toggle svg { position: absolute; top: 7px; width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; }
.theme-toggle .sun { left: 7px; color: var(--on-accent); }
.theme-toggle .moon { right: 7px; color: var(--muted); }
:root[data-theme="dark"] .theme-toggle .sun { color: var(--muted); }
:root[data-theme="dark"] .theme-toggle .moon { color: var(--on-accent); }
.theme-toggle .sun, .theme-toggle .moon { z-index: 1; }

/* ---------- Buttons ---------- */
.btn { display: inline-flex; align-items: center; gap: 10px; font: 600 .95rem/1 var(--f-ui); text-decoration: none;
  padding: 15px 22px; border-radius: 4px; border: 1px solid transparent; cursor: pointer; transition: transform .2s, background-color .2s, border-color .2s; }
.btn-primary { background: var(--accent); color: var(--on-accent); }
.btn-primary:hover { background: color-mix(in srgb, var(--accent) 88%, var(--text)); }
.btn-ghost { color: var(--text); border-color: var(--line-strong); background: transparent; }
.btn-ghost:hover { border-color: var(--text); }
.btn .arr { transition: transform .2s; }
.btn:hover .arr { transform: translateX(3px); }

/* ---------- Footer ---------- */
.site-foot { border-top: 1px solid var(--line); margin-top: 48px; }
.site-foot .inner { max-width: var(--maxw); margin: 0 auto; padding: 40px var(--gutter) 48px; display: grid; gap: 28px;
  grid-template-columns: 1.3fr 1fr 1fr; color: var(--muted); font-size: .88rem; }
.site-foot h4 { margin: 0 0 10px; font: 500 .72rem/1 var(--f-mono); letter-spacing: .14em; text-transform: uppercase; color: var(--text); }
.site-foot p { margin: 6px 0; max-width: 46ch; }
.site-foot ul { list-style: none; padding: 0; margin: 0; display: grid; gap: 6px; }
.site-foot a { color: var(--muted); text-decoration: none; }
.site-foot a:hover { color: var(--text); text-decoration: underline; }
.site-foot .legal { grid-column: 1 / -1; border-top: 1px solid var(--line); padding-top: 18px; font: 400 .74rem/1.5 var(--f-mono); }

@media (max-width: 820px) {
  .nav-toggle { display: inline-flex; width: 40px; height: 36px; align-items: center; justify-content: center; border: 1px solid var(--line-strong);
    border-radius: 4px; background: var(--surface); color: var(--text); cursor: pointer; }
  .site-nav { position: absolute; top: 100%; left: 0; right: 0; flex-direction: column; align-items: stretch; background: var(--surface);
    border-bottom: 1px solid var(--line); padding: 8px var(--gutter) 14px; display: none; }
  .site-nav.open { display: flex; }
  .head-tools { margin-left: auto; }
  .site-foot .inner { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}
/* Uppercase labels: keep units such as µm lower-case (an uppercased µ reads as "M") */
.keep-case, .eyebrow .u, .tag-chip .u { text-transform: none; letter-spacing: .04em; }