:root {
  --bg: #07080f;
  --bg-2: #0b0d18;
  --panel: rgba(14, 18, 32, 0.78);
  --fg: #e8eef8;
  --fg-dim: #8b93a7;
  --fg-dimmer: #5b6378;
  --line: #2a3352;
  --line-muted: #1a2040;
  --accent: #00d4e4;

  --act-1: #22c55e;
  --act-2: #f59e0b;
  --act-3: #ef4444;

  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --sans: -apple-system, "SF Pro Display", "Inter", system-ui, sans-serif;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background:
    radial-gradient(ellipse at 20% 0%, #101630 0%, transparent 50%),
    radial-gradient(ellipse at 80% 100%, #1a0c30 0%, transparent 50%),
    var(--bg);
  color: var(--fg);
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}

kbd {
  display: inline-block;
  padding: 2px 6px;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 10px;
  color: var(--fg);
  margin: 0 2px;
}

code {
  font-family: var(--mono);
  background: rgba(0, 212, 228, 0.1);
  color: var(--accent);
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 0.9em;
}

/* ----- Header ----- */
#title {
  max-width: 1200px;
  margin: 0 auto;
  padding: 48px 32px 24px;
}

#title h1 {
  margin: 0;
  font-size: 32px;
  font-weight: 800;
  letter-spacing: -0.8px;
}

#title .sub-accent {
  color: var(--fg-dim);
  font-weight: 400;
  font-size: 22px;
}

#title .sub {
  margin: 8px 0 0 0;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--fg-dim);
  letter-spacing: -0.2px;
}

/* ----- Legend ----- */
#legend {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 32px 32px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.4px;
  color: var(--fg);
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--line);
  border-radius: 999px;
}

.badge b {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  font-weight: 700;
  font-size: 11px;
  color: #0b0d18;
}

.badge-1 b { background: var(--act-1); }
.badge-2 b { background: var(--act-2); }
.badge-3 b { background: var(--act-3); }

.badge-1 { border-color: rgba(34, 197, 94, 0.35); }
.badge-2 { border-color: rgba(245, 158, 11, 0.35); }
.badge-3 { border-color: rgba(239, 68, 68, 0.35); }

/* ----- Sequence wrap ----- */
#sequence-wrap {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 16px 180px;
  position: relative;
}

/* Sticky actor row */
#actors {
  position: sticky;
  top: 0;
  z-index: 20;
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 0;
  padding: 14px 0;
  background: linear-gradient(to bottom, var(--bg) 0%, rgba(7, 8, 15, 0.96) 80%, rgba(7, 8, 15, 0.3) 100%);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line-muted);
}

.actor {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 6px;
}

.actor .ico {
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  background: var(--panel);
  border: 1px solid var(--line);
  font-size: 22px;
  backdrop-filter: blur(8px);
  transition: border-color 0.2s, box-shadow 0.2s, transform 0.2s;
}

.actor.highlight .ico {
  border-color: var(--actor-accent, var(--accent));
  box-shadow: 0 0 20px var(--actor-accent, var(--accent));
  transform: translateY(-1px);
}

.actor .name {
  font-size: 12px;
  font-weight: 600;
  color: var(--fg);
}

.actor .note {
  font-size: 9px;
  font-family: var(--mono);
  color: var(--fg-dimmer);
  letter-spacing: 0.2px;
}

/* ----- Diagram ----- */
#diagram {
  display: block;
  width: 100%;
  height: auto;
}

/* Lifelines */
.lifeline {
  stroke: var(--line-muted);
  stroke-width: 1;
  stroke-dasharray: 3 6;
}

/* Act band */
.act-band rect {
  rx: 8;
  ry: 8;
}

.act-band text {
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 2px;
  text-transform: uppercase;
  fill: var(--fg);
}

.act-band .act-sub {
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0;
  text-transform: none;
  fill: var(--fg-dim);
}

/* Messages */
.msg {
  cursor: pointer;
}

.msg .line {
  fill: none;
  stroke-width: 1.5;
  transition: stroke-width 0.15s, opacity 0.15s;
}

.msg .label {
  font-family: var(--sans);
  font-size: 12px;
  font-weight: 500;
  fill: var(--fg);
  pointer-events: none;
}

.msg .sublabel {
  font-family: var(--mono);
  font-size: 10px;
  fill: var(--fg-dim);
  pointer-events: none;
}

.msg .hit {
  fill: transparent;
}

/* Active message */
.msg.active .line {
  stroke-width: 2.5;
  filter: drop-shadow(0 0 6px var(--msg-color, var(--accent)));
}

.msg.active .label {
  fill: #ffffff;
  font-weight: 600;
}

.msg:hover .line {
  stroke-width: 2.2;
}

.msg:hover .label {
  fill: #ffffff;
}

/* Step marker */
.msg .step-marker {
  fill: var(--bg-2);
  stroke-width: 1.5;
}

.msg .step-num {
  font-family: var(--mono);
  font-size: 10px;
  font-weight: 700;
  fill: var(--fg);
  text-anchor: middle;
  dominant-baseline: middle;
  pointer-events: none;
}

/* ----- Detail panel ----- */
#detail {
  position: fixed;
  bottom: 48px;
  left: 50%;
  transform: translateX(-50%);
  width: min(780px, calc(100vw - 32px));
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 16px 20px;
  backdrop-filter: blur(18px);
  z-index: 30;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
}

#detail-head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.pill {
  display: inline-flex;
  align-items: center;
  padding: 3px 10px;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 1px;
  text-transform: uppercase;
  border-radius: 999px;
  background: rgba(0, 212, 228, 0.12);
  color: var(--accent);
  border: 1px solid rgba(0, 212, 228, 0.3);
}

.pill-act {
  background: rgba(255, 255, 255, 0.05);
  color: var(--fg-dim);
  border-color: var(--line);
}

.pill-act.pill-act-1 { background: rgba(34, 197, 94, 0.12); color: var(--act-1); border-color: rgba(34, 197, 94, 0.35); }
.pill-act.pill-act-2 { background: rgba(245, 158, 11, 0.12); color: var(--act-2); border-color: rgba(245, 158, 11, 0.35); }
.pill-act.pill-act-3 { background: rgba(239, 68, 68, 0.12); color: var(--act-3); border-color: rgba(239, 68, 68, 0.35); }

#detail .flow {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--fg-dim);
  letter-spacing: -0.2px;
}

#detail-body {
  margin: 0;
  font-size: 14px;
  line-height: 1.55;
  color: var(--fg);
}

/* ----- Takeaways ----- */
#takeaways {
  max-width: 1200px;
  margin: 40px auto 0;
  padding: 48px 32px 24px;
  border-top: 1px solid var(--line-muted);
}

#takeaways h2 {
  margin: 0 0 28px 0;
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.4px;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 18px;
}

.card {
  padding: 20px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 12px;
  position: relative;
}

.card-num {
  position: absolute;
  top: 14px;
  right: 16px;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 2px;
  color: var(--fg-dimmer);
}

.card h3 {
  margin: 0 0 8px 0;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: -0.2px;
}

.card p {
  margin: 0;
  font-size: 13px;
  line-height: 1.55;
  color: var(--fg-dim);
}

.card code { font-size: 0.92em; }

/* ----- Footer hint ----- */
#foot {
  max-width: 1200px;
  margin: 16px auto 24px;
  padding: 0 32px 120px;
  font-family: var(--mono);
  font-size: 10px;
  color: var(--fg-dimmer);
  text-align: center;
  letter-spacing: 0.2px;
}

/* ----- Responsive ----- */
@media (max-width: 960px) {
  #sequence-wrap { padding-left: 0; padding-right: 0; overflow-x: auto; padding-bottom: 220px; }
  #actors, #diagram { min-width: 900px; }
  #title h1 { font-size: 24px; }
  #title .sub-accent { font-size: 18px; }
  #takeaways h2 { font-size: 18px; }
  #detail { bottom: 24px; width: calc(100vw - 16px); }
}