:root {
  /* Brand */
  --rb-navy: #021E51;
  --rb-messenger-blue: #0084FF;
  --rb-active-blue: #0084FF;

  /* Light theme (default values) */
  --rb-bg: #FFFFFF;
  --rb-bg-secondary: #F0F2F5;
  --rb-bg-tertiary: #E4E6EB;
  --rb-surface: #FFFFFF;
  --rb-text: #050505;
  --rb-text-secondary: #65676B;
  --rb-text-tertiary: #8A8D91;
  --rb-border: #CED0D4;
  --rb-nav-bg: #FFFFFF;
  --rb-nav-border: #CED0D4;
  --rb-shadow: rgba(0, 0, 0, 0.1);
  --rb-danger: #E41E3F;
  --rb-success: #31A24C;
  --rb-warning: #F7B928;

  /* Reading defaults */
  --rb-reading-bg: #F8F1E3; /* Premium Ivory */
  --rb-reading-text: #1A1A1A;
  --rb-reading-margin: 16px;
  --rb-font-size: 18px;
  --rb-line-height: 1.6;
  --rb-paragraph-spacing: 1em;

  /* Sizing */
  --rb-nav-height: 56px;
  --rb-touch-min: 44px;
  --rb-radius: 12px;
  --rb-radius-sm: 8px;
}

/* System / Light */
[data-theme="light"],
:root:not([data-theme="dark"]) {
  color-scheme: light;
}

/* Dark theme */
[data-theme="dark"] {
  color-scheme: dark;
  --rb-bg: #18191A;
  --rb-bg-secondary: #242526;
  --rb-bg-tertiary: #3A3B3C;
  --rb-surface: #242526;
  --rb-text: #E4E6EB;
  --rb-text-secondary: #B0B3B8;
  --rb-text-tertiary: #8A8D91;
  --rb-border: #3A3B3C;
  --rb-nav-bg: #242526;
  --rb-nav-border: #3A3B3C;
  --rb-shadow: rgba(0, 0, 0, 0.4);
}

/* System preference fallback when data-theme="system" */
@media (prefers-color-scheme: dark) {
  :root[data-theme="system"] {
    color-scheme: dark;
    --rb-bg: #18191A;
    --rb-bg-secondary: #242526;
    --rb-bg-tertiary: #3A3B3C;
    --rb-surface: #242526;
    --rb-text: #E4E6EB;
    --rb-text-secondary: #B0B3B8;
    --rb-text-tertiary: #8A8D91;
    --rb-border: #3A3B3C;
    --rb-nav-bg: #242526;
    --rb-nav-border: #3A3B3C;
    --rb-shadow: rgba(0, 0, 0, 0.4);
  }
}

/* Reading background presets (independent of app theme) */
[data-reading-bg="classic-white"] {
  --rb-reading-bg: #FFFFFF;
  --rb-reading-text: #1A1A1A;
}
[data-reading-bg="premium-ivory"] {
  --rb-reading-bg: #F8F1E3;
  --rb-reading-text: #1A1A1A;
}
[data-reading-bg="warm-paper"] {
  --rb-reading-bg: #F5ECD7;
  --rb-reading-text: #2C2416;
}
[data-reading-bg="soft-cream"] {
  --rb-reading-bg: #FFF8E7;
  --rb-reading-text: #2A2A2A;
}
[data-reading-bg="sepia"] {
  --rb-reading-bg: #F4ECD8;
  --rb-reading-text: #5B4636;
}
[data-reading-bg="dark-reading"] {
  --rb-reading-bg: #1C1C1E;
  --rb-reading-text: #E8E6E3;
}