/* 1. TYPOGRAPHY: Native system fonts */
:root {
  --sy-f-sys: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --sy-f-mono: ui-monospace, SFMono-Regular, "JetBrains Mono", monospace;
}

/* 2. LIGHT MODE COLORS */
html[data-theme="light"] {
  --sy-c-text: #334155;
  --sy-c-heading: #0f172a;
  --sy-c-bg: #f8fafc;
}

/* 3. DARK MODE COLORS */
html[data-theme="dark"] {
  --sy-c-bg: #0f172a;       /* Deep slate background instead of pure black */
  --sy-c-text: #cbd5e1;     /* Softer text */
}

/* 4. STRUCTURE: Underline Headers (applies to both modes) */
main h1, 
main h2,
.document h1,
.document h2 {
  border-bottom: 1px solid var(--sy-c-divider);
  padding-bottom: 0.3em;
  margin-top: 1.5em;
  margin-bottom: 0.8em;
}

/* 5. CODE BLOCKS (applies to both modes) */
div.highlight {
  border: 1px solid var(--sy-c-divider);
  border-radius: 6px;
}