:root {
  --color-primary: #003882;
  --color-primary-hover: #002860;
  --color-accent: #0F766E;
  --color-bg: #F8FAFC;
  --color-surface: #FFFFFF;
  --color-border: #E2E8F0;
  --color-text-main: #0F172A;
  --color-text-muted: #475569;
  --color-tag-bg: #EBF3FC;
  --color-tag-text: #003882;
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  --max-width: 860px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06), 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 4px 6px -1px rgba(15, 23, 42, 0.08), 0 2px 4px -2px rgba(15, 23, 42, 0.06);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-primary: #3B82F6;
    --color-primary-hover: #60A5FA;
    --color-accent: #14B8A6;
    --color-bg: #0B132B;
    --color-surface: #131E3A;
    --color-border: #1E2D4A;
    --color-text-main: #F1F5F9;
    --color-text-muted: #94A3B8;
    --color-tag-bg: #1E2E4E;
    --color-tag-text: #93C5FD;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  }
}

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

body {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text-main);
  line-height: 1.65;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

/* Header & Navigation */
header {
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 1.5rem;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--color-text-main);
  font-weight: 700;
  font-size: 1.25rem;
}

.brand-badge {
  font-size: 0.75rem;
  font-weight: 600;
  background-color: var(--color-tag-bg);
  color: var(--color-tag-text);
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
}

.nav-links {
  display: flex;
  gap: 1.25rem;
  list-style: none;
}

.nav-links a {
  text-decoration: none;
  color: var(--color-text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  transition: color 0.15s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-primary);
}

/* Main Container */
main {
  max-width: var(--max-width);
  margin: 2.5rem auto;
  padding: 0 1.5rem;
}

/* Hero & Title */
.doc-header {
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--color-border);
}

.doc-header h1 {
  font-size: 2.1rem;
  color: var(--color-text-main);
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

.doc-meta {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.doc-meta-item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

/* Content Blocks */
.content-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 2.25rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-sm);
}

h2 {
  font-size: 1.4rem;
  color: var(--color-text-main);
  margin-top: 1.8rem;
  margin-bottom: 0.8rem;
  letter-spacing: -0.01em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

h2:first-of-type {
  margin-top: 0;
}

h3 {
  font-size: 1.15rem;
  color: var(--color-text-main);
  margin-top: 1.4rem;
  margin-bottom: 0.5rem;
}

p {
  margin-bottom: 1rem;
  color: var(--color-text-main);
}

p.muted {
  color: var(--color-text-muted);
}

ul, ol {
  margin: 0.75rem 0 1.25rem 1.5rem;
  color: var(--color-text-main);
}

li {
  margin-bottom: 0.45rem;
}

a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 2px;
}

a:hover {
  color: var(--color-primary-hover);
}

/* Callout Box */
.callout {
  background-color: var(--color-tag-bg);
  border-left: 4px solid var(--color-primary);
  padding: 1rem 1.25rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 1.25rem 0;
  font-size: 0.95rem;
}

.callout p {
  margin-bottom: 0;
  color: var(--color-tag-text);
  font-weight: 500;
}

/* Home Feature Grid */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.25rem;
  margin: 2rem 0;
}

.feature-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
}

.feature-card h3 {
  margin-top: 0;
  color: var(--color-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.feature-card p {
  margin-bottom: 0;
  font-size: 0.95rem;
  color: var(--color-text-muted);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.65rem 1.25rem;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  text-decoration: none;
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-primary {
  background-color: var(--color-primary);
  color: #FFFFFF !important;
  text-decoration: none;
}

.btn-primary:hover {
  background-color: var(--color-primary-hover);
}

.btn-outline {
  border: 1px solid var(--color-border);
  background-color: transparent;
  color: var(--color-text-main) !important;
}

.btn-outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary) !important;
}

/* Footer */
footer {
  border-top: 1px solid var(--color-border);
  background-color: var(--color-surface);
  padding: 2.5rem 1.5rem;
  margin-top: 4rem;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.footer-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1.5rem;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.footer-links a {
  color: var(--color-text-muted);
  text-decoration: none;
}

.footer-links a:hover {
  color: var(--color-primary);
  text-decoration: underline;
}

@media (max-width: 640px) {
  .content-card {
    padding: 1.5rem;
  }
  .doc-header h1 {
    font-size: 1.65rem;
  }
}