:root {
  --color-bg: #F7FBFF;
  --color-surface: #FFFFFF;
  --color-text: #123247;
  --color-muted: #4E6A7A;
  --color-border: #CFE3EF;
  --color-primary: #7FB6D9;
  --color-secondary: #A7D6E8;
  --color-accent: #F2B6C6;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(18, 50, 71, 0.10);
  --space: clamp(14px, 2vw, 22px);
  --font-body: ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, Arial, sans-serif;
  --font-heading: ui-serif, Georgia, Cambria, 'Times New Roman', Times, serif;
}

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

html {
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  font-family: var(--font-body);
  font-size: clamp(16px, 1.8vw, 18px);
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  display: grid;
  grid-template-rows: auto 1fr auto;
  min-height: 100vh;
}

h1, h2, h3 {
  font-family: var(--font-heading);
  line-height: 1.3;
  margin-bottom: 0.8em;
  color: var(--color-text);
}

h1 {
  font-size: clamp(28px, 4vw, 42px);
  margin-top: 0.5em;
}

h2 {
  font-size: clamp(22px, 3vw, 32px);
  margin-top: 1.5em;
}

h3 {
  font-size: clamp(18px, 2.5vw, 24px);
  margin-top: 1.2em;
}

p, li {
  margin-bottom: 1em;
}

ul, ol {
  margin-left: 1.5em;
}

a {
  color: var(--color-primary);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
  transition: color 160ms ease, text-decoration-thickness 160ms ease;
}

a:hover {
  color: var(--color-accent);
  text-decoration-thickness: 2px;
}

a:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: 2px;
}

header {
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space) calc(var(--space) * 1.5);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space);
}

.site-name {
  font-family: var(--font-heading);
  font-size: clamp(20px, 2.5vw, 26px);
  font-weight: 600;
  color: var(--color-primary);
}

nav[aria-label="Main navigation"] {
  display: flex;
  gap: calc(var(--space) * 1.2);
  flex-wrap: wrap;
}

nav[aria-label="Main navigation"] a {
  text-decoration: none;
  font-weight: 500;
  color: var(--color-text);
  transition: color 160ms ease;
}

nav[aria-label="Main navigation"] a:hover {
  color: var(--color-primary);
}

nav[aria-label="Main navigation"] a:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: 2px;
}

.breadcrumb {
  background-color: var(--color-surface);
  padding: calc(var(--space) * 0.6) calc(var(--space) * 1.5);
  border-bottom: 1px solid var(--color-border);
}

.breadcrumb ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5em;
  margin: 0;
  font-size: 0.9em;
  color: var(--color-muted);
}

.breadcrumb li:not(:last-child)::after {
  content: '/';
  margin-left: 0.5em;
  color: var(--color-border);
}

.breadcrumb a {
  color: var(--color-primary);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

main {
  padding: calc(var(--space) * 2) calc(var(--space) * 1.5);
  max-width: 1400px;
  width: 100%;
  margin: 0 auto;
}

@media (min-width: 1024px) {
  main {
    display: grid;
    grid-template-columns: 1fr 320px;
    gap: calc(var(--space) * 3);
    align-items: start;
  }
}

article {
  background-color: var(--color-surface);
  padding: calc(var(--space) * 2);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

section {
  margin-bottom: calc(var(--space) * 2);
}

aside {
  background-color: var(--color-surface);
  padding: calc(var(--space) * 1.5);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  border-left: 4px solid var(--color-primary);
}

@media (min-width: 1024px) {
  aside#external-links,
  aside#sources {
    grid-column: 2;
    grid-row: 1;
  }
}

aside h2 {
  font-size: clamp(18px, 2.2vw, 22px);
  margin-top: 0;
}

aside ul {
  margin-left: 1.2em;
}

aside.checkpoint {
  background-color: rgba(127, 182, 217, 0.08);
  border-left-color: var(--color-accent);
  margin: calc(var(--space) * 1.5) 0;
}

blockquote {
  border-left: 4px solid var(--color-primary);
  background-color: rgba(167, 214, 232, 0.1);
  padding: calc(var(--space) * 1.2);
  margin: calc(var(--space) * 1.5) 0;
  font-style: italic;
  color: var(--color-muted);
  border-radius: 4px;
}

blockquote p {
  margin-bottom: 0;
}

.table-wrapper {
  overflow-x: auto;
  margin: calc(var(--space) * 1.5) 0;
  border-radius: var(--radius);
  box-shadow: 0 2px 8px rgba(18, 50, 71, 0.06);
}

table {
  width: 100%;
  border-collapse: collapse;
  background-color: var(--color-surface);
  font-size: 0.95em;
}

caption {
  font-family: var(--font-heading);
  font-size: 1.1em;
  font-weight: 600;
  text-align: left;
  padding: calc(var(--space) * 0.8);
  background-color: var(--color-primary);
  color: var(--color-surface);
  border-radius: var(--radius) var(--radius) 0 0;
}

thead {
  background-color: rgba(127, 182, 217, 0.15);
}

th {
  text-align: left;
  padding: calc(var(--space) * 0.8);
  font-weight: 600;
  color: var(--color-text);
  border-bottom: 2px solid var(--color-border);
}

td {
  padding: calc(var(--space) * 0.8);
  border-bottom: 1px solid var(--color-border);
}

tbody tr:nth-child(even) {
  background-color: rgba(167, 214, 232, 0.08);
}

tbody tr:hover {
  background-color: rgba(127, 182, 217, 0.12);
}

details {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  margin-bottom: calc(var(--space) * 1);
  overflow: hidden;
  transition: border-color 160ms ease;
}

details[open] {
  border-color: var(--color-primary);
}

summary {
  padding: calc(var(--space) * 1);
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  color: var(--color-text);
  transition: background-color 160ms ease, color 160ms ease;
  position: relative;
  padding-left: calc(var(--space) * 2.5);
}

summary::before {
  content: '▸';
  position: absolute;
  left: calc(var(--space) * 1);
  color: var(--color-accent);
  transition: transform 160ms ease;
}

details[open] summary::before {
  transform: rotate(90deg);
}

summary:hover {
  background-color: rgba(127, 182, 217, 0.08);
  color: var(--color-primary);
}

summary:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: -3px;
}

details p {
  padding: 0 calc(var(--space) * 1) calc(var(--space) * 1) calc(var(--space) * 1);
}

footer {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: calc(var(--space) * 1.5);
  text-align: center;
  color: var(--color-muted);
  font-size: 0.9em;
}

footer nav {
  display: flex;
  justify-content: center;
  gap: calc(var(--space) * 1.2);
  flex-wrap: wrap;
  margin-bottom: calc(var(--space) * 0.8);
}

footer nav a {
  color: var(--color-primary);
  text-decoration: none;
  font-weight: 500;
}

footer nav a:hover {
  text-decoration: underline;
}

footer p {
  margin: 0;
}

@media (min-width: 768px) {
  header {
    padding: calc(var(--space) * 1.5) calc(var(--space) * 2.5);
  }
  main {
    padding: calc(var(--space) * 3) calc(var(--space) * 2.5);
  }
  article {
    padding: calc(var(--space) * 2.5);
  }
}

@media (prefers-reduced-motion: reduce) {
  a, summary, details, tr {
    transition: none;
  }
}