/* ============================================================
   MERCURY DESIGN SYSTEM — tokens + components (portfolio subset)
   ------------------------------------------------------------
   Adapted from the Mercury design system for a static site.
   Dark mode follows the visitor's OS preference automatically
   via @media (prefers-color-scheme: dark) instead of the
   design system's opt-in [data-theme="dark"] selector.
   ============================================================ */

/* Fonts are linked from index.html <head> for faster loading. */

:root {
  /* ─── Font families ─────────────────────────────────────── */
  --mer-font-sans: "Geist", ui-sans-serif, -apple-system, "Helvetica Neue", Arial, sans-serif;
  --mer-font-mono: "Geist Mono", ui-monospace, "SF Mono", "JetBrains Mono", Menlo, monospace;
  --mer-font-serif: "Instrument Serif", "Times New Roman", Georgia, serif;

  /* ─── Ink scale (cool neutrals, slightly blue-tinted) ───── */
  --mer-ink-00: #FAFBFC;
  --mer-ink-05: #F4F5F7;
  --mer-ink-10: #ECEEF2;
  --mer-ink-15: #E2E5EB;
  --mer-ink-20: #D4D8E0;
  --mer-ink-30: #B7BCC6;
  --mer-ink-40: #939AA6;
  --mer-ink-50: #6E747E;
  --mer-ink-60: #4A4F58;
  --mer-ink-70: #2D3138;
  --mer-ink-80: #1F2227;
  --mer-ink-90: #16181C;
  --mer-ink-100: #0A0B0D;

  /* ─── Accent: quicksilver blue ──────────────────────────── */
  --mer-accent-50:  oklch(0.97 0.02 240);
  --mer-accent-100: oklch(0.93 0.05 240);
  --mer-accent-200: oklch(0.86 0.09 240);
  --mer-accent-300: oklch(0.76 0.12 240);
  --mer-accent-400: oklch(0.68 0.14 240);
  --mer-accent-500: oklch(0.60 0.15 240);   /* primary */
  --mer-accent-600: oklch(0.52 0.16 244);
  --mer-accent-700: oklch(0.44 0.15 248);
  --mer-accent-900: oklch(0.28 0.10 252);

  /* ─── Signals ───────────────────────────────────────────── */
  --mer-positive: oklch(0.62 0.13 155);
  --mer-positive-soft: oklch(0.94 0.04 155);
  --mer-warning:  oklch(0.74 0.14 75);
  --mer-warning-soft: oklch(0.96 0.05 80);
  --mer-critical: oklch(0.58 0.18 25);
  --mer-critical-soft: oklch(0.95 0.04 25);

  /* ─── Semantic surfaces ─────────────────────────────────── */
  --mer-bg:        var(--mer-ink-00);
  --mer-bg-sunken: var(--mer-ink-05);
  --mer-surface:  #FFFFFF;
  --mer-surface-2: var(--mer-ink-05);
  --mer-overlay:   rgba(10, 11, 13, 0.48);

  --mer-fg:        var(--mer-ink-100);
  --mer-fg-muted:  var(--mer-ink-60);
  --mer-fg-subtle: var(--mer-ink-50);
  --mer-fg-faint:  var(--mer-ink-40);
  --mer-fg-on-accent: #FFFFFF;

  --mer-border:        var(--mer-ink-15);
  --mer-border-strong: var(--mer-ink-20);
  --mer-border-faint:  var(--mer-ink-10);
  --mer-divider:       var(--mer-ink-10);

  /* ─── Radii ─────────────────────────────────────────────── */
  --mer-r-xs: 2px;
  --mer-r-sm: 4px;
  --mer-r-md: 6px;
  --mer-r-lg: 10px;
  --mer-r-xl: 16px;
  --mer-r-pill: 999px;

  /* ─── Shadows (ink-tinted, hairline + lift) ─────────────── */
  --mer-shadow-hair: 0 0 0 0.5px rgba(10, 11, 13, 0.08);
  --mer-shadow-1: 0 1px 2px rgba(10, 11, 13, 0.05), 0 0 0 0.5px rgba(10, 11, 13, 0.05);
  --mer-shadow-2: 0 4px 12px rgba(10, 11, 13, 0.06), 0 0 0 0.5px rgba(10, 11, 13, 0.06);
  --mer-shadow-3: 0 16px 40px rgba(10, 11, 13, 0.10), 0 0 0 0.5px rgba(10, 11, 13, 0.06);
  --mer-shadow-focus: 0 0 0 3px oklch(0.86 0.09 240 / 0.45);

  /* ─── Easing & motion ───────────────────────────────────── */
  --mer-ease: cubic-bezier(0.2, 0.7, 0.1, 1);
  --mer-ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --mer-dur-1: 120ms;
  --mer-dur-2: 220ms;
  --mer-dur-3: 380ms;

  /* ─── Type scale (micro used below) ─────────────────────── */
  --mer-text-body: 15px;
  --mer-lh-body: 1.55;
  --mer-text-micro: 11px;
  --mer-lh-micro: 1.4;
}

/* ─── Dark mode — follows the visitor's OS preference ─────── */
@media (prefers-color-scheme: dark) {
  :root {
    --mer-bg:        var(--mer-ink-100);
    --mer-bg-sunken: #050608;
    --mer-surface:   var(--mer-ink-90);
    --mer-surface-2: var(--mer-ink-80);
    --mer-overlay:   rgba(0, 0, 0, 0.6);

    --mer-fg:        var(--mer-ink-00);
    --mer-fg-muted:  var(--mer-ink-30);
    --mer-fg-subtle: var(--mer-ink-40);
    --mer-fg-faint:  var(--mer-ink-50);

    --mer-border:        var(--mer-ink-80);
    --mer-border-strong: var(--mer-ink-70);
    --mer-border-faint:  var(--mer-ink-90);
    --mer-divider:       var(--mer-ink-80);

    --mer-shadow-hair: 0 0 0 0.5px rgba(255, 255, 255, 0.06);
    --mer-shadow-1: 0 1px 2px rgba(0, 0, 0, 0.5), 0 0 0 0.5px rgba(255, 255, 255, 0.04);
    --mer-shadow-2: 0 4px 16px rgba(0, 0, 0, 0.5), 0 0 0 0.5px rgba(255, 255, 255, 0.05);
    --mer-shadow-3: 0 24px 56px rgba(0, 0, 0, 0.6), 0 0 0 0.5px rgba(255, 255, 255, 0.06);
  }
}

/* ============================================================
   BASE
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--mer-bg);
  color: var(--mer-fg);
  font-family: var(--mer-font-sans);
  font-size: var(--mer-text-body);
  line-height: var(--mer-lh-body);
  font-feature-settings: "ss01", "cv11";
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img { display: block; max-width: 100%; }
a { color: inherit; }
[id] { scroll-margin-top: 88px; }

/* ─── Type helpers ──────────────────────────────────────── */
.mer-micro {
  font-size: var(--mer-text-micro);
  line-height: var(--mer-lh-micro);
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-family: var(--mer-font-mono);
}
.mer-mono { font-family: var(--mer-font-mono); font-feature-settings: "ss02"; }
.mer-serif { font-family: var(--mer-font-serif); font-weight: 400; }

/* ============================================================
   CARD
   ============================================================ */
.mer-card {
  background: var(--mer-surface);
  border: 1px solid var(--mer-border);
  border-radius: var(--mer-r-lg);
  box-shadow: var(--mer-shadow-1);
  padding: 20px;
}

/* ============================================================
   BADGE
   ============================================================ */
.mer-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 2px 8px;
  height: 22px;
  border-radius: var(--mer-r-pill);
  font-family: var(--mer-font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.02em;
  background: var(--mer-ink-10);
  color: var(--mer-ink-80);
}
.mer-badge--accent { background: var(--mer-accent-100); color: var(--mer-accent-700); }

/* ============================================================
   VERTICAL TIMELINE
   ============================================================ */
.mer-vtimeline {
  display: flex;
  flex-direction: column;
  position: relative;
}
.mer-vtimeline-item {
  position: relative;
  display: grid;
  grid-template-columns: 24px 1fr;
  gap: 14px;
  padding-bottom: 22px;
}
.mer-vtimeline-item:last-child { padding-bottom: 0; }

.mer-vtimeline-rail {
  position: relative;
  display: flex;
  justify-content: center;
}
/* connecting line drawn downward from each node (static base track) */
.mer-vtimeline-item:not(:last-child) .mer-vtimeline-rail::after {
  content: "";
  position: absolute;
  top: 20px;
  bottom: -22px;
  left: 50%;
  width: 1.5px;
  transform: translateX(-50%);
  background: var(--mer-border-strong);
}

/* node dot — default */
.mer-tl-dot {
  position: relative;
  z-index: 1;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--mer-ink-30);
  box-shadow: 0 0 0 3px var(--mer-surface), 0 0 0 4px var(--mer-border-strong);
  margin-top: 3px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--mer-surface);
  flex-shrink: 0;
}

/* dot state colors */
.mer-tl-node--done .mer-tl-dot   { background: var(--mer-ink-100); }
.mer-tl-node--active .mer-tl-dot { background: var(--mer-accent-500); }

/* active dot pulse ring */
.mer-tl-node--active .mer-tl-dot::before {
  content: "";
  position: absolute;
  inset: -5px;
  border-radius: 50%;
  border: 1.5px solid var(--mer-accent-500);
  opacity: 0.35;
}

/* content */
.mer-vtimeline-content { padding-top: 1px; min-width: 0; }
.mer-tl-time {
  font-family: var(--mer-font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  color: var(--mer-fg-subtle);
  margin-bottom: 3px;
}
.mer-tl-title {
  font-size: 14px;
  font-weight: 600;
  letter-spacing: -0.006em;
  color: var(--mer-fg);
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.mer-tl-desc {
  font-size: 13px;
  color: var(--mer-fg-muted);
  line-height: 1.5;
  margin-top: 3px;
}
