/* ─── Design Tokens ───────────────────────────────────────────────── */
:root {
  --font-body: 'Space Grotesk', 'Helvetica Neue', sans-serif;
  --font-mono: 'Space Mono', 'Courier New', monospace;

  --text-xs:   clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem, 1.2rem + 1.25vw, 2.25rem);
  --text-2xl:  clamp(2rem, 1.2rem + 2.5vw, 3.5rem);

  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;

  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  --transition-fast: 120ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-med: 200ms cubic-bezier(0.16, 1, 0.3, 1);

  --content-wide: 1280px;
}

/* ─── Color Palette — Payments Dark/Finance Theme ────────────────── */
:root, [data-theme="dark"] {
  --color-bg:             #0d0f14;
  --color-surface:        #131720;
  --color-surface-2:      #181d27;
  --color-surface-offset: #1e2433;
  --color-divider:        #252c3d;
  --color-border:         #2e3650;

  --color-text:           #e2e6f0;
  --color-text-muted:     #7a82a0;
  --color-text-faint:     #414866;

  /* Finance green primary */
  --color-primary:        #00d4a1;
  --color-primary-dim:    rgba(0, 212, 161, 0.12);
  --color-primary-glow:   rgba(0, 212, 161, 0.25);

  /* Accent gold */
  --color-accent:         #f5c542;
  --color-accent-dim:     rgba(245, 197, 66, 0.12);

  /* Category colors */
  --cat-p2p:         #5b8cff;
  --cat-rails:       #00d4a1;
  --cat-mobile:      #a78bfa;
  --cat-faster:      #38bdf8;
  --cat-crypto:      #f5c542;
  --cat-regulation:  #fb7185;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.4);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.5);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.6);
}

[data-theme="light"] {
  --color-bg:             #f4f6fb;
  --color-surface:        #ffffff;
  --color-surface-2:      #f9fafc;
  --color-surface-offset: #eef1f8;
  --color-divider:        #dde1ef;
  --color-border:         #c8cfe3;

  --color-text:           #0d1225;
  --color-text-muted:     #5a6282;
  --color-text-faint:     #9ba5c0;

  --color-primary:        #009e78;
  --color-primary-dim:    rgba(0, 158, 120, 0.1);
  --color-primary-glow:   rgba(0, 158, 120, 0.2);

  --color-accent:         #c49a00;
  --color-accent-dim:     rgba(196, 154, 0, 0.1);

  --cat-p2p:         #3b6ef5;
  --cat-rails:       #009e78;
  --cat-mobile:      #7c5ce8;
  --cat-faster:      #0284c7;
  --cat-crypto:      #c49a00;
  --cat-regulation:  #e84565;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.1);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.14);
}

/* ─── Reset ───────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  scroll-padding-top: 80px;
}
body {
  min-height: 100dvh;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  transition: background var(--transition-med), color var(--transition-med);
}

/* ─── Header ──────────────────────────────────────────────────────── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
}
.header-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-3) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
}
.header-brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.brand-title {
  display: block;
  font-size: var(--text-base);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--color-text);
  line-height: 1.2;
}
.brand-sub {
  display: block;
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  color: var(--color-primary);
  letter-spacing: 0.08em;
}
.header-controls {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-wrap: wrap;
}
.filter-pills {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}
.pill {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 500;
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  border: 1px solid var(--color-border);
  background: transparent;
  color: var(--color-text-muted);
  cursor: pointer;
  transition: all var(--transition-fast);
  letter-spacing: 0.02em;
}
.pill:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
  border-color: var(--color-text-faint);
}
.pill.active {
  background: var(--color-primary);
  color: #000;
  border-color: var(--color-primary);
  font-weight: 700;
}
.theme-toggle {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background: transparent;
  color: var(--color-text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}
.theme-toggle:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
}

/* ─── Stat Bar ────────────────────────────────────────────────────── */
.stat-bar {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}
.stat-bar-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-5) var(--space-6);
  display: flex;
  align-items: center;
  gap: var(--space-6);
  flex-wrap: wrap;
}
.stat-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.stat-value {
  font-size: var(--text-xl);
  font-weight: 700;
  font-family: var(--font-mono);
  color: var(--color-primary);
  letter-spacing: -0.03em;
  line-height: 1;
}
.stat-label {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  font-weight: 500;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}
.stat-divider {
  width: 1px;
  height: 40px;
  background: var(--color-border);
  flex-shrink: 0;
}

/* ─── Volume Chart ────────────────────────────────────────────────── */
.chart-section {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-10) var(--space-6) var(--space-6);
}
.chart-header {
  margin-bottom: var(--space-6);
}
.chart-header h2 {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}
.chart-sub {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  margin-top: var(--space-1);
  display: block;
}
.chart-container {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6) var(--space-6) var(--space-4);
  overflow-x: auto;
}
.chart-bars {
  display: flex;
  align-items: flex-end;
  gap: var(--space-3);
  height: 160px;
  min-width: 600px;
}
.chart-bar-group {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
  cursor: default;
}
.chart-bar-wrap {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-end;
  height: 140px;
  position: relative;
}
.chart-bar {
  width: 100%;
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
  background: var(--color-primary);
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  min-height: 3px;
  position: relative;
  overflow: visible;
}
.chart-bar:hover { opacity: 0.85; transform: scaleY(1.03); transform-origin: bottom; }
.chart-bar-label {
  position: absolute;
  top: -22px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.6rem;
  font-family: var(--font-mono);
  color: var(--color-primary);
  font-weight: 700;
  white-space: nowrap;
}
.chart-year {
  font-size: 0.65rem;
  font-family: var(--font-mono);
  color: var(--color-text-muted);
  text-align: center;
  letter-spacing: 0.04em;
}

/* ─── Timeline Section ────────────────────────────────────────────── */
.timeline-section {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-6) var(--space-6) var(--space-16);
}
.timeline-wrapper {
  position: relative;
}
.timeline-spine {
  position: absolute;
  left: 50%;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(to bottom, var(--color-primary) 0%, var(--color-accent) 50%, var(--cat-regulation) 100%);
  transform: translateX(-50%);
  opacity: 0.35;
  border-radius: 2px;
}
.timeline-events {
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* Year Banner */
.year-banner {
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
  padding: var(--space-8) 0 var(--space-4);
  z-index: 2;
}
.year-badge {
  background: var(--color-bg);
  border: 2px solid var(--color-primary);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  padding: var(--space-2) var(--space-5);
  border-radius: var(--radius-full);
  letter-spacing: 0.1em;
  box-shadow: 0 0 24px var(--color-primary-glow);
}

/* Milestone Event Card */
.event-row {
  display: grid;
  grid-template-columns: 1fr 48px 1fr;
  gap: 0;
  align-items: start;
  position: relative;
  margin-bottom: var(--space-4);
  transition: opacity var(--transition-med);
}
.event-row.hidden { display: none; }

/* Left and right slot */
.event-left,
.event-right {
  padding: 0 var(--space-5);
}
.event-left { text-align: right; }
.event-right { text-align: left; }

/* Center spine node */
.event-node {
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
  padding-top: var(--space-3);
}
.node-dot {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  border: 2px solid var(--color-bg);
  flex-shrink: 0;
  position: relative;
  z-index: 2;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}
.event-row:hover .node-dot {
  transform: scale(1.4);
  box-shadow: 0 0 12px currentColor;
}

/* Card */
.event-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-4) var(--space-5);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast), transform var(--transition-fast);
  cursor: default;
}
.event-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.card-meta {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}
.event-left .card-meta { justify-content: flex-end; flex-direction: row-reverse; }
.card-month {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.card-cat-badge {
  font-size: 0.65rem;
  font-weight: 700;
  padding: 2px var(--space-2);
  border-radius: var(--radius-full);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: #000;
}
.card-title {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.01em;
  line-height: 1.3;
  margin-bottom: var(--space-2);
}
.card-body {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  line-height: 1.6;
  max-width: 52ch;
}
.event-left .card-body { margin-left: auto; }
.card-volume {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  margin-top: var(--space-2);
  padding: var(--space-1) var(--space-2);
  background: var(--color-surface-offset);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 700;
  color: var(--color-text-muted);
  letter-spacing: 0.04em;
}
.card-volume::before {
  content: '▸';
  font-size: 0.5rem;
}

/* Critical milestone highlight */
.event-card.critical {
  border-width: 2px;
}
.event-card.critical .card-title {
  font-size: var(--text-base);
}

/* Category color assignments */
.cat-p2p        { --cat-color: var(--cat-p2p); }
.cat-rails      { --cat-color: var(--cat-rails); }
.cat-mobile     { --cat-color: var(--cat-mobile); }
.cat-faster     { --cat-color: var(--cat-faster); }
.cat-crypto     { --cat-color: var(--cat-crypto); }
.cat-regulation { --cat-color: var(--cat-regulation); }

.event-card { border-color: var(--cat-color); }
.event-card:hover { border-color: var(--cat-color); box-shadow: 0 4px 20px color-mix(in oklab, var(--cat-color) 25%, transparent); }
.node-dot { background: var(--cat-color); color: var(--cat-color); }
.card-cat-badge { background: var(--cat-color); }

/* Critical glow */
.event-card.critical {
  box-shadow: 0 0 0 1px var(--cat-color), 0 4px 24px color-mix(in oklab, var(--cat-color) 30%, transparent);
}

/* ─── Legend dots ─────────────────────────────────────────────────── */
.legend-dot[data-cat="p2p"]        { background: var(--cat-p2p); }
.legend-dot[data-cat="rails"]      { background: var(--cat-rails); }
.legend-dot[data-cat="mobile"]     { background: var(--cat-mobile); }
.legend-dot[data-cat="faster"]     { background: var(--cat-faster); }
.legend-dot[data-cat="crypto"]     { background: var(--cat-crypto); }
.legend-dot[data-cat="regulation"] { background: var(--cat-regulation); }

/* ─── Article Link in card ───────────────────────────────────────── */
.card-article-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  margin-top: var(--space-3);
  padding: var(--space-2) var(--space-3);
  background: var(--cat-color);
  color: #000;
  font-size: var(--text-xs);
  font-weight: 700;
  border-radius: var(--radius-md);
  text-decoration: none;
  letter-spacing: 0.02em;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}
.card-article-link:hover {
  opacity: 0.85;
  transform: translateX(2px);
}

/* ─── Footer ──────────────────────────────────────────────────────── */
.site-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
}
.footer-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-6) var(--space-6);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}
.legend {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  flex-wrap: wrap;
}
.legend-title {
  font-size: var(--text-xs);
  font-weight: 700;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.legend-items {
  display: flex;
  gap: var(--space-4);
  flex-wrap: wrap;
}
.legend-item {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  font-weight: 500;
}
.legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
}
.footer-sources {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  line-height: 1.5;
  font-style: italic;
}

/* ─── Scroll reveal ───────────────────────────────────────────────── */
.event-card {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease, border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.event-card.visible {
  opacity: 1;
  transform: translateY(0);
}
.event-card.critical.visible {
  box-shadow: 0 0 0 1px var(--cat-color), 0 4px 24px color-mix(in oklab, var(--cat-color) 30%, transparent);
}
.event-card.visible:hover {
  transform: translateY(-2px);
}

/* ─── Responsive ──────────────────────────────────────────────────── */
@media (max-width: 768px) {
  .timeline-spine {
    left: var(--space-4);
  }
  .event-row {
    grid-template-columns: 28px 1fr;
    grid-template-rows: auto;
  }
  .event-left {
    display: none;
  }
  .event-node {
    padding-top: var(--space-3);
    align-items: center;
  }
  .event-right {
    text-align: left;
    padding: 0 0 0 var(--space-4);
  }
  .year-banner {
    justify-content: flex-start;
    padding-left: var(--space-8);
  }
  .stat-bar-inner {
    gap: var(--space-4);
  }
  .stat-divider { display: none; }
  .header-inner { padding: var(--space-3) var(--space-4); }
  .chart-section, .timeline-section { padding-left: var(--space-4); padding-right: var(--space-4); }
}

@media (max-width: 480px) {
  .filter-pills { gap: var(--space-1); }
  .pill { padding: var(--space-1) var(--space-2); }
  .stat-value { font-size: var(--text-lg); }
}

/* Grid for left-side events on mobile becomes single-col right */
@media (max-width: 768px) {
  .event-row[data-side="left"] .event-left { display: none; }
  .event-row[data-side="left"] .event-right { display: block; }
}