/* ==========================================================================
   Mac Fold — Apple Design System Foundation
   Inspired by Apple.com & Apple Developer Design Language
   Author: Dalchand Rana (@dalchandrana)
   ========================================================================== */

:root {
  /* Color Palette — Apple Space Black / Dark Mode Default */
  --bg-primary: #000000;
  --bg-secondary: #0a0a0c;
  --bg-tertiary: #141418;
  --bg-card: rgba(26, 26, 32, 0.65);
  --bg-card-hover: rgba(36, 36, 46, 0.8);
  --bg-glass: rgba(18, 18, 22, 0.72);
  --bg-glass-elevated: rgba(28, 28, 35, 0.85);

  /* Apple Aluminum & Metallic Tones */
  --metal-space-black: #1a1a1e;
  --metal-highlight: #3a3a44;
  --metal-lip: #2d2d34;
  --metal-notch: #070709;

  /* Typography Colors */
  --text-primary: #f5f5f7;
  --text-secondary: #86868b;
  --text-tertiary: #515154;
  --text-quaternary: #333336;
  --text-inverse: #000000;

  /* Mac Fold Brand Accent (International Orange from native macOS UI) */
  --accent-brand: #ff6b18;
  --accent-brand-subtle: rgba(255, 107, 24, 0.12);
  --accent-brand-border: rgba(255, 107, 24, 0.35);
  --accent-brand-hover: #ff8533;
  --accent-brand-active: #e65600;

  /* Apple System Colors */
  --apple-blue: #2997ff;
  --apple-green: #30d158;
  --apple-yellow: #ffd60a;
  --apple-red: #ff453a;
  --apple-purple: #bf5af2;

  /* Borders & Dividers */
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-regular: rgba(255, 255, 255, 0.14);
  --border-strong: rgba(255, 255, 255, 0.22);
  --border-glow: rgba(255, 107, 24, 0.4);

  /* Shadows */
  --shadow-subtle: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-elevation: 0 12px 36px rgba(0, 0, 0, 0.55);
  --shadow-card: 0 20px 60px rgba(0, 0, 0, 0.7);
  --shadow-glow: 0 0 40px rgba(255, 107, 24, 0.2);

  /* Typography */
  --font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Menlo", "Monaco", "Cascadia Code", monospace;

  /* Layout */
  --max-width: 1200px;
  --max-width-narrow: 980px;
  --max-width-wide: 1360px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-full: 9999px;

  /* Header & Navigation */
  --nav-height: 52px;

  /* Transitions */
  --transition-fast: 0.18s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-smooth: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-slow: 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Light Theme Support */
[data-theme="light"] {
  --bg-primary: #fbfbfd;
  --bg-secondary: #f5f5f7;
  --bg-tertiary: #e8e8ed;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-hover: rgba(255, 255, 255, 1);
  --bg-glass: rgba(255, 255, 255, 0.82);
  --bg-glass-elevated: rgba(255, 255, 255, 0.95);

  --metal-space-black: #e2e2e7;
  --metal-highlight: #ffffff;
  --metal-lip: #d0d0d5;
  --metal-notch: #1d1d1f;

  --text-primary: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #86868b;
  --text-quaternary: #d2d2d7;
  --text-inverse: #ffffff;

  --accent-brand: #c65a16;
  --accent-brand-subtle: rgba(198, 90, 22, 0.08);
  --accent-brand-border: rgba(198, 90, 22, 0.28);
  --accent-brand-hover: #db661b;
  --accent-brand-active: #a84b11;

  --border-subtle: rgba(0, 0, 0, 0.06);
  --border-regular: rgba(0, 0, 0, 0.12);
  --border-strong: rgba(0, 0, 0, 0.2);
  --border-glow: rgba(198, 90, 22, 0.3);

  --shadow-subtle: 0 4px 12px rgba(0, 0, 0, 0.05);
  --shadow-elevation: 0 12px 32px rgba(0, 0, 0, 0.08);
  --shadow-card: 0 20px 48px rgba(0, 0, 0, 0.1);
  --shadow-glow: 0 0 35px rgba(198, 90, 22, 0.15);
}

/* Reset & Global Defaults */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.5;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  overflow-x: hidden;
  position: relative;
}

/* Apple Typography Defaults */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  font-weight: 600;
  line-height: 1.12;
  letter-spacing: -0.025em;
}

h1 {
  font-size: clamp(2.5rem, 5.5vw, 4.5rem);
  letter-spacing: -0.035em;
  font-weight: 700;
}

h2 {
  font-size: clamp(2rem, 3.8vw, 3.25rem);
  letter-spacing: -0.03em;
}

h3 {
  font-size: clamp(1.35rem, 2.2vw, 1.85rem);
  letter-spacing: -0.02em;
}

p {
  color: var(--text-secondary);
  font-size: 1.0625rem;
  line-height: 1.6;
  letter-spacing: -0.01em;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast), opacity var(--transition-fast);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

/* Containers */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.container-narrow {
  width: 100%;
  max-width: var(--max-width-narrow);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.container-wide {
  width: 100%;
  max-width: var(--max-width-wide);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

/* Apple Sticky Navigation Header */
.apple-nav-wrapper {
  position: sticky;
  top: 0;
  z-index: 1000;
  width: 100%;
  background: var(--bg-glass);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--border-subtle);
  transition: background-color var(--transition-smooth), border-color var(--transition-smooth);
}

.apple-nav {
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.apple-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 1.0625rem;
  color: var(--text-primary);
  letter-spacing: -0.015em;
}

.apple-brand img {
  width: 26px;
  height: 26px;
  border-radius: 6px;
  object-fit: cover;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
}

.apple-nav-links {
  display: flex;
  align-items: center;
  gap: 26px;
  list-style: none;
}

.apple-nav-links a {
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-weight: 400;
  letter-spacing: -0.01em;
  padding: 6px 0;
  position: relative;
}

.apple-nav-links a:hover,
.apple-nav-links a.active {
  color: var(--text-primary);
}

.apple-nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* Apple Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 500;
  line-height: 1;
  padding: 11px 22px;
  border-radius: var(--radius-full);
  letter-spacing: -0.01em;
  transition: all var(--transition-fast);
  text-align: center;
  white-space: nowrap;
}

.btn-sm {
  font-size: 0.8125rem;
  padding: 7px 14px;
}

.btn-lg {
  font-size: 1.0625rem;
  padding: 14px 28px;
  font-weight: 600;
}

/* Primary Apple Button — International Orange / Vibrant Accent */
.btn-primary {
  background: linear-gradient(180deg, #ff7b2b 0%, #ff5e0a 100%);
  color: #ffffff;
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow: 0 2px 8px rgba(255, 107, 24, 0.35), inset 0 1px 1px rgba(255, 255, 255, 0.4);
}

.btn-primary:hover {
  background: linear-gradient(180deg, #ff8c42 0%, #ff6e1a 100%);
  box-shadow: 0 4px 18px rgba(255, 107, 24, 0.5), inset 0 1px 1px rgba(255, 255, 255, 0.6);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0);
  background: #e65600;
}

/* Secondary Apple Button — Frosted Glass with Hairline Border */
.btn-secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-regular);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.btn-secondary:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-strong);
  color: #ffffff;
  transform: translateY(-1px);
}

.btn-secondary:active {
  transform: translateY(0);
}

/* Apple Eyebrow / Badges */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-brand);
  background: var(--accent-brand-subtle);
  border: 1px solid var(--accent-brand-border);
  padding: 5px 12px;
  border-radius: var(--radius-full);
  margin-bottom: 16px;
}

.eyebrow .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--accent-brand);
  box-shadow: 0 0 8px var(--accent-brand);
}

.eyebrow-blue {
  color: var(--apple-blue);
  background: rgba(41, 151, 255, 0.1);
  border-color: rgba(41, 151, 255, 0.3);
}
.eyebrow-blue .dot {
  background-color: var(--apple-blue);
  box-shadow: 0 0 8px var(--apple-blue);
}

/* Apple Keycaps `<kbd>` */
kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-primary);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.14) 0%, rgba(255, 255, 255, 0.04) 100%);
  border: 1px solid var(--border-regular);
  border-bottom: 2px solid rgba(0, 0, 0, 0.5);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3), inset 0 1px 0 rgba(255, 255, 255, 0.2);
  border-radius: 6px;
  padding: 3px 8px;
  min-width: 24px;
  height: 24px;
  margin: 0 2px;
}

/* Apple Cards & Glass Panels */
.apple-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: 36px;
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  transition: all var(--transition-smooth);
  position: relative;
  overflow: hidden;
}

.apple-card:hover {
  border-color: var(--border-regular);
  background: var(--bg-card-hover);
  box-shadow: var(--shadow-card);
}

/* Theme Toggle Button */
.theme-toggle {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  border: 1px solid transparent;
}

.theme-toggle:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
  border-color: var(--border-subtle);
}

/* Mobile Nav Toggle */
.mobile-nav-toggle {
  display: none;
  width: 36px;
  height: 36px;
  align-items: center;
  justify-content: center;
  color: var(--text-primary);
}

@media (max-width: 820px) {
  .apple-nav-links {
    display: none;
  }
  .mobile-nav-toggle {
    display: flex;
  }
  .apple-nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--bg-glass-elevated);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    padding: 24px;
    gap: 18px;
    border-bottom: 1px solid var(--border-subtle);
    box-shadow: var(--shadow-elevation);
  }
}