* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  color-scheme: light;
  --bg: #f6f7fb;
  --card: #ffffff;
  --ink: #121826;
  --muted: #5f6b7b;
  --border: #e4e7ec;
  --accent: #2563eb;
  --accent-soft: rgba(37, 99, 235, 0.15);
  --warning: #d97706;
}

body {
  font-family: "Inter", "Segoe UI", system-ui, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.5;
}

.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: 32px 24px 48px;
}

.hero {
  margin-bottom: 28px;
}

.hero h1 {
  font-size: 2.2rem;
  margin: 6px 0 12px;
  letter-spacing: -0.02em;
}

.eyebrow {
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 0.15em;
  color: var(--accent);
}

.subhead {
  color: var(--muted);
  max-width: 720px;
}

.layout {
  display: grid;
  grid-template-columns: minmax(260px, 320px) minmax(0, 1fr);
  gap: 20px;
  align-items: start;
}

.panel {
  display: grid;
  gap: 16px;
}

.panel-block,
.canvas-card,
.graph-card {
  background: var(--card);
  border-radius: 16px;
  padding: 18px 20px;
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.06);
  border: 1px solid var(--border);
}

.panel-block h2,
.canvas-card h2,
.graph-card h2 {
  font-size: 1rem;
  margin-bottom: 12px;
  color: var(--ink);
}

.control {
  display: grid;
  gap: 8px;
  margin-bottom: 16px;
  font-size: 0.95rem;
  color: var(--muted);
}

.control strong {
  color: var(--ink);
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

select {
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #fff;
  font-size: 0.95rem;
}

.metrics {
  display: grid;
  gap: 12px;
}

.metric {
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: var(--muted);
  font-size: 0.95rem;
}

.metric strong {
  color: var(--ink);
  font-size: 1.1rem;
}

.warning {
  margin-top: 12px;
  padding: 10px 12px;
  border-radius: 10px;
  background: rgba(217, 119, 6, 0.12);
  color: var(--warning);
  font-weight: 600;
  font-size: 0.9rem;
}

.hidden {
  display: none;
}

.assumptions {
  list-style: none;
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: 0.9rem;
}

.visual {
  display: grid;
  gap: 16px;
}

.canvas-card {
  position: relative;
}

#flowCanvas {
  width: 100%;
  height: 360px;
  border-radius: 12px;
  background: linear-gradient(180deg, #f8fafc 0%, #eef2ff 100%);
}

.legend {
  display: flex;
  gap: 16px;
  align-items: center;
  font-size: 0.85rem;
  color: var(--muted);
  margin-top: 12px;
}

.legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
  margin-right: 6px;
}

.legend-dot.upper {
  background: var(--accent);
}

.legend-dot.lower {
  background: rgba(37, 99, 235, 0.4);
}

.graphs {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
  margin-top: 24px;
}

.graph-card canvas {
  width: 100%;
  height: 220px;
  border-radius: 10px;
  background: #fbfdff;
  border: 1px solid var(--border);
}

@media (max-width: 960px) {
  .layout {
    grid-template-columns: 1fr;
  }
}