/**
 * Theme: Blue (Professional & Trustworthy)
 * Modern, SPA-like design with a professional blue color scheme
 * Perfect for learning and education platforms
 */

:root {
  /* ============================================
     COLOR PALETTE - Blue Theme
     ============================================ */

  /* Primary Colors - Blue */
  --color-primary: #2563eb;
  --color-primary-dark: #1e40af;
  --color-primary-light: #3b82f6;
  --color-primary-lighter: #60a5fa;
  --color-primary-lightest: #dbeafe;

  /* Secondary Colors - Slate/Gray */
  --color-secondary: #64748b;
  --color-secondary-dark: #475569;
  --color-secondary-light: #94a3b8;
  --color-secondary-lighter: #cbd5e1;
  --color-secondary-lightest: #f1f5f9;

  /* Accent Colors */
  --color-accent: #0ea5e9;
  --color-accent-light: #38bdf8;

  /* Semantic Colors */
  --color-success: #10b981;
  --color-success-light: #34d399;
  --color-success-bg: #d1fae5;

  --color-warning: #f59e0b;
  --color-warning-light: #fbbf24;
  --color-warning-bg: #fef3c7;

  --color-danger: #ef4444;
  --color-danger-light: #f87171;
  --color-danger-bg: #fee2e2;

  --color-info: #06b6d4;
  --color-info-light: #22d3ee;
  --color-info-bg: #cffafe;

  /* Neutral Colors */
  --color-text-primary: #0f172a;
  --color-text-secondary: #475569;
  --color-text-muted: #64748b;
  --color-text-light: #94a3b8;
  --color-text-inverse: #ffffff;

  /* Background Colors */
  --color-bg-primary: #ffffff;
  --color-bg-secondary: #f8fafc;
  --color-bg-tertiary: #f1f5f9;
  --color-bg-hover: #f8fafc;
  --color-bg-active: #e2e8f0;

  /* Border Colors */
  --color-border: #e2e8f0;
  --color-border-light: #f1f5f9;
  --color-border-dark: #cbd5e1;
  --color-border-focus: #2563eb;

  /* ============================================
     TYPOGRAPHY
     ============================================ */

  --font-family-base: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-family-heading: -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;      /* 12px */
  --font-size-sm: 0.875rem;    /* 14px */
  --font-size-base: 1rem;       /* 16px */
  --font-size-lg: 1.125rem;     /* 18px */
  --font-size-xl: 1.25rem;      /* 20px */
  --font-size-2xl: 1.5rem;      /* 24px */
  --font-size-3xl: 1.875rem;    /* 30px */
  --font-size-4xl: 2.25rem;     /* 36px */
  --font-size-5xl: 3rem;        /* 48px */

  --font-weight-light: 300;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

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

  /* ============================================
     SPACING SCALE
     ============================================ */

  --spacing-0: 0;
  --spacing-1: 0.25rem;   /* 4px */
  --spacing-2: 0.5rem;    /* 8px */
  --spacing-3: 0.75rem;   /* 12px */
  --spacing-4: 1rem;      /* 16px */
  --spacing-5: 1.25rem;   /* 20px */
  --spacing-6: 1.5rem;    /* 24px */
  --spacing-8: 2rem;      /* 32px */
  --spacing-10: 2.5rem;   /* 40px */
  --spacing-12: 3rem;     /* 48px */
  --spacing-16: 4rem;     /* 64px */
  --spacing-20: 5rem;     /* 80px */
  --spacing-24: 6rem;     /* 96px */

  /* ============================================
     BORDERS & RADIUS
     ============================================ */

  --border-width: 1px;
  --border-width-thick: 2px;
  --border-style: solid;

  --border-radius-none: 0;
  --border-radius-sm: 0.25rem;   /* 4px */
  --border-radius-md: 0.375rem;  /* 6px */
  --border-radius-lg: 0.5rem;    /* 8px */
  --border-radius-xl: 0.75rem;   /* 12px */
  --border-radius-2xl: 1rem;     /* 16px */
  --border-radius-full: 9999px;

  /* ============================================
     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);
  --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.06);
  --shadow-none: none;

  /* ============================================
     TRANSITIONS
     ============================================ */

  --transition-fast: 150ms ease-in-out;
  --transition-base: 200ms ease-in-out;
  --transition-slow: 300ms ease-in-out;

  /* ============================================
     Z-INDEX SCALE
     ============================================ */

  --z-index-dropdown: 1000;
  --z-index-sticky: 1020;
  --z-index-fixed: 1030;
  --z-index-modal-backdrop: 1040;
  --z-index-modal: 1050;
  --z-index-popover: 1060;
  --z-index-tooltip: 1070;

  /* ============================================
     LAYOUT
     ============================================ */

  --container-max-width: 1200px;
  --container-padding: var(--spacing-4);

  /* ============================================
     COMPONENT-SPECIFIC
     ============================================ */

  /* Buttons */
  --btn-padding-y: 0.625rem;
  --btn-padding-x: 1.25rem;
  --btn-font-size: var(--font-size-base);
  --btn-font-weight: var(--font-weight-medium);
  --btn-border-radius: var(--border-radius-lg);

  /* Cards */
  --card-padding: var(--spacing-6);
  --card-border-radius: var(--border-radius-xl);
  --card-shadow: var(--shadow-md);
  --card-bg: var(--color-bg-primary);

  /* Forms */
  --form-input-padding-y: 0.625rem;
  --form-input-padding-x: 0.875rem;
  --form-input-border-radius: var(--border-radius-lg);
  --form-input-border: var(--border-width) var(--border-style) var(--color-border);
  --form-input-focus-border: var(--border-width-thick) var(--border-style) var(--color-border-focus);

  /* Modals */
  --modal-backdrop-bg: rgba(15, 23, 42, 0.75);
  --modal-border-radius: var(--border-radius-xl);
  --modal-shadow: var(--shadow-xl);
}

/* ============================================
   GLOBAL STYLES
   ============================================ */

body {
  font-family: var(--font-family-base);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-secondary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Smooth scrolling */
html {
  scroll-behavior: smooth;
}

/* Focus styles for accessibility */
*:focus-visible {
  outline: 2px solid var(--color-border-focus);
  outline-offset: 2px;
}

/* Selection styles */
::selection {
  background-color: var(--color-primary-lightest);
  color: var(--color-primary-dark);
}