/* ====================================
   DESIGN SYSTEM: ELITE OPERATOR PORTFOLIO
   ====================================
   
   Inspired by: Stripe, Linear, Notion
   Philosophy: Typography-heavy, whitespace-first
   Palette: Black, White, Neutral Grey, 1 Accent
   
==================================== */

/* ---- VARIABLES ---- */
:root {
  /* Color Palette — Premium Light Executive */
  --color-black: #0b0f1a;
  --color-white: #ffffff;
  --color-gray-50: #f7f4ef;
  --color-gray-100: #f1f4f9;
  --color-gray-200: #e2e8f0;
  --color-gray-300: #cbd5f5;
  --color-gray-400: #94a3b8;
  --color-gray-500: #64748b;
  --color-gray-600: #475569;
  --color-gray-700: #334155;
  --color-gray-800: #1e293b;
  --color-gray-900: #0f172a;
  
  /* Accent: Single premium deep blue */
  --color-accent: #1d4ed8;      /* deep blue */
  --color-accent-light: #e8edff; /* soft blue wash */
  --color-accent-strong: #0b3abf;
  
  /* Semantic */
  --color-text-primary: #0f172a;
  --color-text-secondary: #475569;
  --color-text-tertiary: #94a3b8;
  --color-border: #e2e8f0;
  --color-border-strong: #cbd5e1;
  --color-bg-primary: #f7f4ef;
  --color-bg-secondary: #ffffff;
  --color-bg-surface: #eef1f6;
  --color-bg-glass: rgba(255, 255, 255, 0.72);
  
  /* Typography */
  --font-family-serif: 'Playfair Display', serif;
  --font-family-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  
  --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: 3.25rem;        /* 52px */
  
  --line-height-tight: 1.25;
  --line-height-snug: 1.375;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.625;
  --line-height-loose: 1.875;
  
  --font-weight-light: 300;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  /* Spacing */
  --space-0: 0;
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.25rem;   /* 20px */
  --space-6: 1.5rem;    /* 24px */
  --space-8: 2rem;      /* 32px */
  --space-10: 2.5rem;   /* 40px */
  --space-12: 3rem;     /* 48px */
  --space-16: 4rem;     /* 64px */
  --space-20: 5rem;     /* 80px */
  --space-24: 6rem;     /* 96px */
  
  /* Layout */
  --max-width-content: 48rem;      /* 768px */
  --max-width-wide: 64rem;         /* 1024px */
  --max-width-full: 80rem;         /* 1280px */
  
  /* Radius */
  --radius-none: 0;
  --radius-sm: 0.25rem;   /* 4px */
  --radius-md: 0.5rem;    /* 8px */
  --radius-lg: 0.75rem;   /* 12px */
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 12px 24px rgba(15, 23, 42, 0.12);
  --shadow-lg: 0 20px 40px rgba(15, 23, 42, 0.16);
  --shadow-xl: 0 30px 60px rgba(15, 23, 42, 0.22);
  
  /* Transitions */
  --transition-fast: 160ms ease-out;
  --transition-base: 240ms ease-out;
  --transition-slow: 420ms ease-out;
  
  /* Z-index */
  --z-base: 0;
  --z-dropdown: 10;
  --z-sticky: 20;
  --z-fixed: 30;
  --z-modal: 40;
  --z-popover: 50;
}

/* ---- DARK MODE ---- */
@media (prefers-color-scheme: dark) {
  :root {
    --color-text-primary: #f8fafc;
    --color-text-secondary: #cbd5f5;
    --color-text-tertiary: #94a3b8;
    --color-border: #243041;
    --color-border-strong: #334155;
    --color-bg-primary: #0b0f1a;
    --color-bg-secondary: #121826;
    --color-bg-surface: #141b2d;
    --color-bg-glass: rgba(15, 23, 42, 0.7);
    --color-accent: #3b82f6;
    --color-accent-light: #1e2b4a;
    --color-accent-strong: #1d4ed8;
  }
}

:root[data-theme="dark"] {
  --color-text-primary: #f8fafc;
  --color-text-secondary: #cbd5f5;
  --color-text-tertiary: #94a3b8;
  --color-border: #243041;
  --color-border-strong: #334155;
  --color-bg-primary: #0b0f1a;
  --color-bg-secondary: #121826;
  --color-bg-surface: #141b2d;
  --color-bg-glass: rgba(15, 23, 42, 0.7);
  --color-accent: #3b82f6;
  --color-accent-light: #1e2b4a;
  --color-accent-strong: #1d4ed8;
}

/* ====================================
   RESET & BASE
==================================== */

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family-sans);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  background-image: radial-gradient(1200px 600px at 8% -10%, rgba(29, 78, 216, 0.06), transparent 60%),
    radial-gradient(900px 500px at 90% 0%, rgba(15, 23, 42, 0.04), transparent 60%);
  transition: background-color var(--transition-base), color var(--transition-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body.page-transition {
  opacity: 0;
  transform: translateY(8px);
}

body.page-transition.page-loaded {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 700ms ease, transform 700ms ease;
}

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

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-snug);
  margin: 0;
}

h1 {
  font-size: var(--font-size-5xl);
  font-weight: var(--font-weight-semibold);
  letter-spacing: -0.02em;
  margin-bottom: var(--space-6);
}

h2 {
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-semibold);
  letter-spacing: -0.01em;
  margin-bottom: var(--space-4);
  margin-top: var(--space-12);
}

h3 {
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--space-3);
  margin-top: var(--space-6);
}

h4 {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  margin-bottom: var(--space-2);
}

p {
  margin-bottom: var(--space-4);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

p strong {
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
}

/* ---- SPECIAL TEXT ---- */

.lead {
  font-size: var(--font-size-lg);
  line-height: var(--line-height-relaxed);
  color: var(--color-text-primary);
  font-weight: var(--font-weight-normal);
  margin-bottom: var(--space-8);
}

.text-secondary {
  color: var(--color-text-secondary);
}

.text-tertiary {
  color: var(--color-text-tertiary);
}

/* ====================================
   LINKS
==================================== */

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
  border-bottom: 1px solid transparent;
}

a:hover {
  opacity: 0.7;
  border-bottom-color: var(--color-accent);
}

/* ====================================
   LISTS
==================================== */

ul, ol {
  margin-bottom: var(--space-4);
  padding-left: var(--space-8);
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

li {
  margin-bottom: var(--space-3);
}

li strong {
  color: var(--color-text-primary);
}

/* ====================================
   CONTAINER & LAYOUT
==================================== */

.container {
  width: 100%;
  max-width: var(--max-width-content);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.container-wide {
  max-width: var(--max-width-wide);
}

.container-full {
  max-width: var(--max-width-full);
}

/* ====================================
   BUTTONS
==================================== */

.btn {
  display: inline-block;
  padding: var(--space-3) var(--space-6);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  text-align: center;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: transform var(--transition-base), box-shadow var(--transition-base), background-color var(--transition-base), color var(--transition-base);
  background-color: transparent;
  color: inherit;
  text-decoration: none;
}

.btn-primary {
  background-color: var(--color-accent);
  color: var(--color-bg-primary);
  border-color: var(--color-accent);
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background-color: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}

.btn-secondary:hover {
  background-color: var(--color-accent-light);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

/* ====================================
   SECTION SPACING
==================================== */

section {
  margin-bottom: var(--space-20);
}

section:last-child {
  margin-bottom: var(--space-12);
}

/* ====================================
   UTILITIES
==================================== */

.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-accent);
  color: var(--color-bg-primary);
  padding: var(--space-2) var(--space-4);
  text-decoration: none;
  z-index: var(--z-popover);
}

.skip-link:focus {
  top: 0;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* ====================================
   PREMIUM UTILITIES
==================================== */

.eyebrow {
  font-size: var(--font-size-sm);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-4);
}

.display {
  font-family: var(--font-family-serif);
  font-weight: var(--font-weight-semibold);
  letter-spacing: -0.02em;
}

.card {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-border-strong);
}

.glass {
  background: var(--color-bg-glass);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  backdrop-filter: blur(16px);
  box-shadow: var(--shadow-sm);
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border-radius: 999px;
  background-color: var(--color-accent-light);
  color: var(--color-accent-strong);
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-semibold);
}

.link-underline {
  background-image: linear-gradient(currentColor, currentColor);
  background-size: 0% 1px;
  background-position: 0% 100%;
  background-repeat: no-repeat;
  transition: background-size var(--transition-base);
  border-bottom: none;
}

.link-underline:hover {
  background-size: 100% 1px;
}

.fade-section {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 700ms ease, transform 700ms ease;
}

.fade-section.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ====================================
   RESPONSIVE
==================================== */

@media (max-width: 768px) {
  h1 {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--space-4);
  }
  
  h2 {
    font-size: var(--font-size-2xl);
    margin-top: var(--space-8);
  }
  
  .container {
    padding: 0 var(--space-4);
  }
}

@media (max-width: 640px) {
  h1 {
    font-size: var(--font-size-3xl);
  }
  
  h2 {
    font-size: var(--font-size-xl);
    margin-top: var(--space-6);
  }
  
  .lead {
    font-size: var(--font-size-base);
  }
}