/* ===================================
   CSS CUSTOM PROPERTIES
   Design System Variables
   =================================== */

:root {
  /* ========== GRADIENTS - Professional Engineering Theme ========== */

  /* Primary Gradients - Deep Blue to Cyan (Corporate Professional) */
  --gradient-primary: linear-gradient(135deg, #0f2027 0%, #203a43 50%, #2c5364 100%);
  --gradient-secondary: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
  --gradient-accent: linear-gradient(135deg, #00d2ff 0%, #3a7bd5 100%);
  --gradient-tech: linear-gradient(135deg, #134e5e 0%, #71b280 100%);
  --gradient-ai: linear-gradient(135deg, #2193b0 0%, #6dd5ed 100%);

  /* Special Gradients */
  --gradient-hero: linear-gradient(135deg, #0f2027 0%, #203a43 30%, #2c5364 60%, #00d2ff 100%);
  --gradient-data: linear-gradient(135deg, #1e3c72 0%, #2a5298 50%, #00d2ff 100%);

  /* Professional Spectrum for Skills/Charts */
  --gradient-spectrum: linear-gradient(135deg, #134e5e 0%, #2193b0 25%, #3a7bd5 50%, #00d2ff 75%, #6dd5ed 100%);

  /* Animated Gradients */
  --gradient-animated-1: linear-gradient(45deg, #0f2027, #203a43, #2c5364, #00d2ff);
  --gradient-animated-2: linear-gradient(270deg, #1e3c72, #2a5298, #3a7bd5, #6dd5ed);

  /* ========== COLORS ========== */

  /* Text Colors */
  --color-text-primary: #1a1a2e;
  --color-text-secondary: #4a4a68;
  --color-text-light: #8b8b9e;
  --color-text-white: #ffffff;

  /* Background Colors */
  --color-bg-primary: #ffffff;
  --color-bg-secondary: #f8f9fa;
  --color-bg-dark: #0f0f23;
  --color-bg-overlay: rgba(0, 0, 0, 0.5);

  /* Accent Colors - Professional Engineering Theme */
  --color-accent-navy: #0f2027;
  --color-accent-blue: #2a5298;
  --color-accent-cyan: #00d2ff;
  --color-accent-teal: #2193b0;
  --color-accent-green: #71b280;

  /* Status Colors */
  --color-success: #6bcf7f;
  --color-error: #f5576c;
  --color-warning: #fee140;
  --color-info: #4facfe;

  /* ========== SPACING ========== */
  --spacing-xs: 0.5rem;      /* 8px */
  --spacing-sm: 1rem;        /* 16px */
  --spacing-md: 2rem;        /* 32px */
  --spacing-lg: 4rem;        /* 64px */
  --spacing-xl: 8rem;        /* 128px */
  --spacing-2xl: 12rem;      /* 192px */

  /* Container */
  --container-max-width: 1200px;
  --container-padding: 2rem;

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

  /* Font Families */
  --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto',
                  'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans',
                  'Helvetica Neue', sans-serif;
  --font-heading: 'Inter', var(--font-primary);
  --font-mono: 'Fira Code', 'Courier New', monospace;

  /* Font Sizes - Fluid Typography */
  --font-size-xs: clamp(0.75rem, 1vw, 0.875rem);      /* 12-14px */
  --font-size-sm: clamp(0.875rem, 1.5vw, 1rem);       /* 14-16px */
  --font-size-base: clamp(1rem, 2vw, 1.125rem);       /* 16-18px */
  --font-size-md: clamp(1.125rem, 2.5vw, 1.25rem);    /* 18-20px */
  --font-size-lg: clamp(1.25rem, 3vw, 1.5rem);        /* 20-24px */
  --font-size-xl: clamp(1.5rem, 4vw, 2rem);           /* 24-32px */
  --font-size-2xl: clamp(2rem, 5vw, 3rem);            /* 32-48px */
  --font-size-3xl: clamp(2.5rem, 6vw, 3.5rem);        /* 40-56px */
  --font-size-4xl: clamp(3rem, 8vw, 5rem);            /* 48-80px */

  /* Font Weights */
  --font-weight-light: 300;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  --font-weight-black: 900;

  /* Line Heights */
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.8;

  /* Letter Spacing */
  --letter-spacing-tight: -0.02em;
  --letter-spacing-normal: 0;
  --letter-spacing-wide: 0.05em;

  /* ========== SHADOWS ========== */
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.15);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.2);
  --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.25);

  /* Colored Shadows - Professional Blue */
  --shadow-glow-navy: 0 0 20px rgba(15, 32, 39, 0.5);
  --shadow-glow-blue: 0 0 20px rgba(42, 82, 152, 0.5);
  --shadow-glow-cyan: 0 0 20px rgba(0, 210, 255, 0.5);
  --shadow-glow-tech: 0 0 30px rgba(0, 210, 255, 0.3),
                       0 0 60px rgba(42, 82, 152, 0.2);

  /* ========== BORDER RADIUS ========== */
  --radius-xs: 0.25rem;    /* 4px */
  --radius-sm: 0.5rem;     /* 8px */
  --radius-md: 1rem;       /* 16px */
  --radius-lg: 1.5rem;     /* 24px */
  --radius-xl: 2rem;       /* 32px */
  --radius-full: 9999px;   /* Fully rounded */

  /* ========== TRANSITIONS ========== */
  --transition-fast: 0.15s ease-in-out;
  --transition-base: 0.3s ease-in-out;
  --transition-slow: 0.5s ease-in-out;
  --transition-very-slow: 0.8s ease-in-out;

  /* Easing Functions */
  --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-out: cubic-bezier(0, 0, 0.2, 1);
  --ease-in: cubic-bezier(0.4, 0, 1, 1);
  --ease-bounce: cubic-bezier(0.68, -0.55, 0.265, 1.55);

  /* ========== Z-INDEX LAYERS ========== */
  --z-base: 1;
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-fixed: 300;
  --z-modal-backdrop: 400;
  --z-modal: 500;
  --z-popover: 600;
  --z-tooltip: 700;

  /* ========== BREAKPOINTS ========== */
  --breakpoint-mobile: 320px;
  --breakpoint-tablet: 768px;
  --breakpoint-desktop: 1024px;
  --breakpoint-wide: 1440px;

  /* ========== EFFECTS ========== */

  /* Glassmorphism */
  --glass-bg: rgba(255, 255, 255, 0.1);
  --glass-border: rgba(255, 255, 255, 0.2);
  --glass-blur: blur(10px);

  /* Backdrop Filters */
  --backdrop-blur-sm: blur(8px);
  --backdrop-blur-md: blur(12px);
  --backdrop-blur-lg: blur(16px);

  /* ========== ANIMATION DURATIONS ========== */
  --duration-instant: 0.1s;
  --duration-fast: 0.2s;
  --duration-normal: 0.3s;
  --duration-slow: 0.5s;
  --duration-very-slow: 1s;
  --duration-extra-slow: 2s;

  /* ========== MISCELLANEOUS ========== */

  /* Header */
  --header-height: 80px;
  --header-height-mobile: 60px;

  /* Section Padding */
  --section-padding: clamp(4rem, 10vw, 8rem);
  --section-padding-small: clamp(2rem, 5vw, 4rem);

  /* Grid Gaps */
  --gap-xs: 0.5rem;
  --gap-sm: 1rem;
  --gap-md: 2rem;
  --gap-lg: 3rem;
  --gap-xl: 4rem;
}

/* ===================================
   DARK MODE VARIABLES (Optional)
   =================================== */
@media (prefers-color-scheme: dark) {
  :root {
    --color-text-primary: #ffffff;
    --color-text-secondary: #b8b8c8;
    --color-text-light: #8b8b9e;

    --color-bg-primary: #0f0f23;
    --color-bg-secondary: #1a1a2e;
    --color-bg-overlay: rgba(255, 255, 255, 0.05);

    --glass-bg: rgba(26, 26, 46, 0.3);
    --glass-border: rgba(255, 255, 255, 0.1);
  }
}

/* ===================================
   GRADIENT ANIMATION KEYFRAMES
   =================================== */
@keyframes gradient-shift {
  0%, 100% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
}

@keyframes gradient-rotate {
  0% {
    background-position: 0% 50%;
  }
  25% {
    background-position: 50% 100%;
  }
  50% {
    background-position: 100% 50%;
  }
  75% {
    background-position: 50% 0%;
  }
  100% {
    background-position: 0% 50%;
  }
}