:root {
  color-scheme: light;
  --navy: #001e5f;
  --blue: #0066fd;
  --blue-soft: #eef5ff;
  --yellow: #ffd82b;
  --yellow-soft: #fff9d8;
  --ink: #172033;
  --muted: #5b6678;
  --line: #d8e0eb;
  --bg: #f7f9fc;
  --surface: #ffffff;
  --green: #0b6b42;
  --red: #a12020;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.55;
}

a {
  color: inherit;
}

.topbar {
  background: #ffffff;
  border-bottom: 1px solid var(--line);
}

.topbar-inner,
.page {
  max-width: 1180px;
  margin: 0 auto;
  padding-inline: clamp(1rem, 3vw, 1.5rem);
}

.topbar-inner {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: center;
  padding-block: 0.75rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 1rem;
  text-decoration: none;
}

.brand img {
  width: 230px;
  max-width: 46vw;
  height: auto;
}

.brand span {
  padding-left: 1rem;
  border-left: 1px solid var(--line);
  color: var(--navy);
  font-weight: 900;
}

.page {
  padding-block: 1.15rem 2.5rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 36px;
  padding: 0.55rem 0.85rem;
  border: 1px solid var(--navy);
  border-radius: 6px;
  background: var(--navy);
  color: #ffffff;
  font-size: 0.9rem;
  font-weight: 850;
  text-decoration: none;
}

.button.secondary {
  border-color: var(--line);
  background: #ffffff;
  color: var(--navy);
}

.hero,
.panel,
.topic-card {
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--surface);
  box-shadow: 0 18px 44px -38px rgba(0, 30, 95, 0.45);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 1rem;
  align-items: end;
  padding: clamp(1rem, 3vw, 1.4rem);
}

.label {
  margin: 0 0 0.45rem;
  color: var(--blue);
  font-size: 0.78rem;
  font-weight: 900;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  color: var(--navy);
  line-height: 1.15;
}

h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.55rem);
}

.lead {
  max-width: 760px;
  margin: 0.55rem 0 0;
  color: var(--muted);
  font-size: 1.02rem;
}

.grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 0.9rem;
  margin-top: 0.9rem;
}

.panel {
  padding: 1rem;
}

.panel h2 {
  margin: 0 0 0.55rem;
  font-size: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.panel p,
.panel li {
  color: #2f394b;
}

.panel ul {
  margin: 0;
  padding-left: 1.15rem;
}

.stack {
  display: grid;
  gap: 0.9rem;
}

.mini-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
}

.callout {
  border-left: 5px solid var(--yellow);
  background: var(--yellow-soft);
}

.practice-options {
  display: grid;
  gap: 0.5rem;
  margin-top: 0.7rem;
}

.practice-options button {
  width: 100%;
  padding: 0.7rem 0.8rem;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #ffffff;
  color: var(--navy);
  font: inherit;
  font-weight: 750;
  text-align: left;
  cursor: pointer;
}

.practice-options button.correct {
  border-color: rgba(11, 107, 66, 0.55);
  background: rgba(11, 107, 66, 0.08);
  color: var(--green);
}

.practice-options button.incorrect {
  border-color: rgba(161, 32, 32, 0.45);
  background: rgba(161, 32, 32, 0.08);
  color: var(--red);
}

.feedback {
  display: none;
  margin-top: 0.65rem;
  padding: 0.7rem;
  border-radius: 6px;
  background: var(--blue-soft);
  color: var(--navy);
  font-weight: 750;
}

.topic-list {
  display: grid;
  gap: 1rem;
  margin-top: 0.9rem;
}

.topic-group {
  display: grid;
  gap: 0.7rem;
}

.topic-group h2 {
  margin: 0;
  color: var(--navy);
  font-size: 0.95rem;
  letter-spacing: 0;
  text-transform: uppercase;
}

.topic-list-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.85rem;
}

.topic-card {
  display: grid;
  min-height: 160px;
  padding: 1rem;
  color: var(--navy);
  text-decoration: none;
}

.topic-card span {
  color: var(--muted);
}

.related-panel {
  margin-top: 0.9rem;
}

.anchor-panel {
  margin-top: 0.9rem;
}

.anchor-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 0.9rem;
}

.anchor-grid h3 {
  margin: 0 0 0.45rem;
  color: var(--navy);
  font-size: 0.86rem;
  letter-spacing: 0;
  text-transform: uppercase;
}

.source-list {
  display: grid;
  gap: 0.45rem;
  padding-left: 1rem;
}

.source-list li {
  color: var(--muted);
  font-size: 0.9rem;
}

.source-list a {
  color: var(--navy);
  font-weight: 850;
}

.source-list span {
  display: block;
  margin-top: 0.1rem;
  color: var(--muted);
}

.related-links {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.55rem;
}

.related-links a {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  align-items: center;
  min-height: 42px;
  padding: 0.62rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #ffffff;
  color: var(--navy);
  font-size: 0.9rem;
  font-weight: 800;
  text-decoration: none;
}

.related-links a:hover,
.related-links a:focus-visible {
  background: var(--blue-soft);
  outline: 3px solid rgba(0, 102, 253, 0.14);
  outline-offset: 1px;
}

.related-links span {
  color: var(--blue);
  font-weight: 950;
}

footer {
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.85rem;
}

@media (max-width: 860px) {
  .topbar-inner,
  .brand,
  .hero {
    align-items: flex-start;
    flex-direction: column;
  }

  .brand span {
    padding-left: 0;
    border-left: 0;
  }

  .grid,
  .mini-grid,
  .topic-list-grid,
  .anchor-grid,
  .related-links {
    grid-template-columns: 1fr;
  }
}