/**
 * CSS Variables - Core (Theme-Neutral)
 * 
 * Contains base variables that are shared across all themes:
 * - Spacing & sizing
 * - Transitions & animations
 * - Box shadows
 * - Border radius
 * - Z-index layers
 * 
 * Color variables are defined in theme files:
 * - /css/themes/light.css
 * - /css/themes/dark.css
 */

:root {
    /* -----------------------------------------------------------------------------
       SPACING & SIZING
       ----------------------------------------------------------------------------- */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;

    --container-max-width: 1400px;
    --content-max-width: 900px;

    /* -----------------------------------------------------------------------------
       TRANSITIONS & ANIMATIONS
       ----------------------------------------------------------------------------- */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 350ms ease;

    /* -----------------------------------------------------------------------------
       BOX SHADOWS
       ----------------------------------------------------------------------------- */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

    /* -----------------------------------------------------------------------------
       BORDER RADIUS
       ----------------------------------------------------------------------------- */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-full: 9999px;

    /* -----------------------------------------------------------------------------
       Z-INDEX LAYERS
       ----------------------------------------------------------------------------- */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;

    /* -----------------------------------------------------------------------------
       TYPOGRAPHY
       ----------------------------------------------------------------------------- */
    --font-family-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-family-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, "Courier New", monospace;

    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;

    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;

    /* -----------------------------------------------------------------------------
       LAYOUT
       ----------------------------------------------------------------------------- */
    --header-height: 60px;
    --footer-height: auto;
    --sidebar-width: 250px;
}