:root {
  --serif: 'Source Serif 4', Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono: 'JetBrains Mono', 'SFMono-Regular', Menlo, monospace;

  --bg: #fdfcf9;
  --paper: #ffffff;
  --text: #2f2a22;
  --muted: #6e665b;
  --border: #e2d8c6;
  --accent: #2c6fb7;
  --accent-hover: #1e528a;
  --warm: #d9622b;
  --warm-soft: #fad9c8;
  --cool-soft: #e2eaf5;
  --target: #d9622b;
  --network: #2c6fb7;
  --neuron: #1e7770;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--serif);
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
}

.article { max-width: 980px; margin: 0 auto; padding: 2.5rem 1.5rem 5rem; }

.back-link {
  display: inline-block;
  margin-bottom: 1.5rem;
  color: var(--muted);
  text-decoration: none;
  font-family: var(--sans);
  font-size: 0.9rem;
  transition: color 0.2s;
}
.back-link:hover { color: var(--text); }

.article-header { margin-bottom: 3rem; text-align: center; }
.kicker {
  margin: 0 0 0.75rem;
  font-family: var(--sans);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--muted);
}
h1 {
  margin: 0 auto 1rem;
  font-size: clamp(2.3rem, 5vw, 3.4rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  max-width: 16ch;
  color: #1a1815;
}
.abstract {
  margin: 0 auto;
  max-width: 62ch;
  font-size: 1.15rem;
  color: #4d463d;
}
.byline {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 1.4rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.92rem;
}

.step-section {
  position: relative;
  margin-top: 4rem;
  padding: 3rem 2.5rem;
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.03);
}

.step-badge {
  position: absolute;
  top: -16px;
  left: 32px;
  background: var(--accent);
  color: white;
  font-family: var(--sans);
  font-weight: 700;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.4rem 1.2rem;
  border-radius: 999px;
  box-shadow: 0 4px 12px rgba(44, 111, 183, 0.25);
}

h2 {
  margin: 0 0 1rem;
  font-size: clamp(1.6rem, 3.5vw, 2.2rem);
  line-height: 1.15;
  color: #1a1815;
}
h3 {
  margin-top: 2rem;
  margin-bottom: 0.8rem;
  font-size: 1.25rem;
  color: #1a1815;
}
p { max-width: 68ch; font-size: 1.1rem; }

code {
  font-family: var(--mono);
  font-size: 0.92em;
  background: rgba(0, 0, 0, 0.05);
  padding: 0.2em 0.4em;
  border-radius: 6px;
}

.button-row {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin: 1.5rem 0 0.5rem;
}
.mode-button {
  border: 1px solid var(--border);
  background: white;
  color: var(--text);
  padding: 0.7rem 1.2rem;
  border-radius: 999px;
  font: 600 0.95rem var(--sans);
  cursor: pointer;
  transition: all 150ms ease;
  box-shadow: 0 2px 8px rgba(0,0,0,0.02);
}
.mode-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.06);
  border-color: var(--accent);
}
.mode-button.is-active {
  background: var(--text);
  color: white;
  border-color: var(--text);
}

.action-btn {
  border: none;
  background: var(--text);
  color: white;
  padding: 0.8rem 1.4rem;
  border-radius: 12px;
  font: 600 1rem var(--sans);
  cursor: pointer;
  transition: all 150ms ease;
  box-shadow: 0 4px 14px rgba(0,0,0,0.1);
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
}
.action-btn:hover {
  transform: translateY(-2px);
  background: #1a1815;
  box-shadow: 0 6px 20px rgba(0,0,0,0.15);
}
.action-btn:disabled { opacity: 0.5; cursor: not-allowed; transform: none; }
.action-btn--primary {
  background: var(--accent);
  font-size: 1.1rem;
  padding: 0.9rem 2.2rem;
  border-radius: 14px;
}
.action-btn--primary:hover { background: var(--accent-hover); }
.action-btn--ghost {
  background: white;
  color: var(--text);
  border: 1px solid var(--border);
  box-shadow: none;
}
.action-btn--ghost:hover { background: #f5f0e5; color: var(--text); }

.interactive-figure {
  margin: 2rem 0;
  padding: 1.5rem 2rem;
  background: white;
  border: 1px solid var(--border);
  border-radius: 20px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.04);
}
canvas { width: 100%; height: auto; display: block; }
figcaption {
  margin-top: 1rem;
  color: var(--muted);
  font-size: 0.95rem;
  text-align: center;
  font-family: var(--sans);
}

.math-block {
  margin: 1.2rem 0;
  text-align: center;
  overflow-x: auto;
}

.callout {
  margin: 1.5rem 0;
  padding: 1rem 1.2rem;
  border-radius: 0 12px 12px 0;
  font-size: 1rem;
}
.callout strong { font-family: var(--sans); font-size: 0.9rem; }
.callout--think { border-left: 3px solid var(--accent); background: rgba(44, 111, 183, 0.04); }
.callout--warn { border-left: 3px solid var(--warm); background: rgba(217, 98, 43, 0.04); }

.explanation-list {
  max-width: 68ch;
  font-size: 1.1rem;
  padding-left: 1.5rem;
}
.explanation-list li { margin-bottom: 0.8rem; }

.control-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  margin: 1rem 0 1.5rem;
}
.control-block {
  background: #faf7ef;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1.2rem;
}
.control-block label {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-family: var(--sans);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.5rem;
}
.control-block label span {
  font-family: var(--mono);
  font-size: 1rem;
  color: var(--text);
  font-weight: 700;
  text-transform: none;
  letter-spacing: 0;
}
.control-block input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

.chip-row {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-top: 0.25rem;
}
.chip {
  padding: 0.3rem 0.8rem;
  border-radius: 999px;
  background: white;
  border: 1px solid var(--border);
  font: 600 0.82rem var(--sans);
  cursor: pointer;
  transition: all 150ms ease;
  color: var(--muted);
}
.chip:hover {
  border-color: var(--accent);
  color: var(--text);
}
.chip.is-active {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

.stat-strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  margin: 1rem 0 0.5rem;
}
.stat-pill {
  background: white;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 0.9rem 1rem;
  text-align: center;
}
.stat-label {
  display: block;
  margin-bottom: 0.3rem;
  font-family: var(--sans);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
}
.stat-value {
  font: 700 1.5rem var(--sans);
  color: var(--text);
  line-height: 1;
}
.stat-pill--accent .stat-value { color: var(--accent); }
.stat-pill--warm .stat-value { color: var(--warm); }

.train-row {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  align-items: center;
  margin-top: 0.5rem;
}

.misconception-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}
.misconception-card {
  padding: 1.2rem;
  border: 1px solid rgba(200, 50, 50, 0.15);
  border-radius: 14px;
  background: rgba(200, 50, 50, 0.03);
}
.misconception-card p { margin: 0; font-size: 0.95rem; line-height: 1.55; }
.misconception-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.2rem 0.8rem;
  border-radius: 16px;
  background: rgba(200, 50, 50, 0.1);
  color: #c03030;
  font-family: var(--sans);
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.examples-table-wrap { overflow-x: auto; margin: 1.5rem 0; }
.examples-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: 0.95rem;
}
.examples-table th,
.examples-table td {
  padding: 0.8rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}
.examples-table th {
  background: rgba(0,0,0,0.02);
  color: var(--muted);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-size: 0.82rem;
}

.reveal-card {
  background: #1a1815;
  color: white;
  border-radius: 22px;
  padding: 2.2rem 2rem;
  text-align: center;
  margin: 2rem 0 1rem;
  box-shadow: 0 20px 50px rgba(0,0,0,0.12);
}
.reveal-card h3 {
  margin: 0 0 0.4rem;
  font-size: 1.25rem;
  font-weight: 500;
  color: #e2d8c6;
}
.reveal-number {
  font: 700 3rem var(--sans);
  color: #ffc266;
  line-height: 1.1;
}
.reveal-card p {
  margin: 0.8rem auto 0;
  max-width: 56ch;
  color: #c8beae;
  font-size: 1rem;
}

@media (max-width: 880px) {
  .control-row, .stat-strip { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .article { padding-inline: 1rem; }
  .step-section { padding: 2rem 1.5rem; }
  .action-btn { width: 100%; justify-content: center; }
}