:root {
  --text: #1f2328;
  --muted: #6b7280;
  --bg: #ffffff;
  --surface: #f6f7f9;
  --line: #e2e5ea;
  --a: #b4452f;
  --b: #2f6f8f;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Lato", system-ui, sans-serif;
  font-size: 1.0625rem;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
}

main {
  max-width: 48rem;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}

a { color: inherit; }

nav { font-size: 0.9rem; color: var(--muted); }

h1 { font-size: 2.25rem; font-weight: 900; line-height: 1.2; margin: 1rem 0 0.5rem; }
h2 { font-size: 1.4rem; font-weight: 700; margin: 2.5rem 0 0.5rem; }

.spark {
  font-size: 1.25rem;
  font-weight: 300;
  color: var(--muted);
  margin: 0 0 2rem;
}

/* Two concepts side by side; stacked on narrow screens */
.versus {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 2rem;
}

.concept { border-top: 4px solid var(--line); padding-top: 0.5rem; }
.concept.a { border-color: var(--a); }
.concept.b { border-color: var(--b); }
.concept h2 { margin: 0; }
.concept p { margin: 0.25rem 0 0; color: var(--muted); }
.concept img { width: 100%; height: auto; display: block; }

/* Tables */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
}

table {
  width: 100%;
  table-layout: fixed;
  border-collapse: collapse;
  font-size: 0.95rem;
}

th, td {
  text-align: left;
  vertical-align: top;
  padding: 0.65rem 0.9rem;
  border-bottom: 1px solid var(--line);
}

td img { display: block; max-width: 100%; height: auto; }

thead th {
  background: var(--surface);
  font-weight: 700;
  border-bottom: 2px solid var(--line);
}
thead th:first-child { width: 26%; }
thead th.a, thead th.b { text-align: center; }
thead th.a { color: var(--a); }
thead th.b { color: var(--b); }

tbody th { font-weight: 700; width: 26%; }
tbody tr:nth-child(even) { background: var(--surface); }
tbody tr:last-child th,
tbody tr:last-child td { border-bottom: 0; }

.example dt { font-weight: 700; margin-top: 0.75rem; }
.example dd { margin: 0; }

.topics { list-style: none; padding: 0; }
.topics li { border-bottom: 1px solid var(--line); }
.topics a {
  display: block;
  padding: 0.9rem 0;
  text-decoration: none;
  font-size: 1.2rem;
  font-weight: 700;
}
.topics a:hover { color: var(--a); }

@media (max-width: 560px) {
  h1 { font-size: 1.8rem; }
  .versus { grid-template-columns: 1fr; }
  th, td { padding: 0.5rem 0.55rem; font-size: 0.85rem; }
  tbody th, thead th:first-child { width: 28%; }
}