/* ═══════════════════════════════════════════════════════════
   QRForge — Design System
   Apple-inspired, deep navy palette, refined typography
   ═══════════════════════════════════════════════════════════ */

@import url('https://fonts.googleapis.com/css2?family=DM+Sans:ital,opsz,wght@0,9..40,300;0,9..40,400;0,9..40,500;0,9..40,600;1,9..40,300&family=DM+Mono:wght@400;500&display=swap');

/* ─── CSS Variables ─────────────────────────────────────── */
:root {
  /* Core palette */
  --navy-900: #00002a;
  --navy-800: #000838;
  --navy-700: #001050;
  --blue-700: #1a3f75;
  --blue-600: #1e4d8c;
  --blue-500: #2563b0;
  --blue-400: #3b82d4;
  --slate:    #2d4a50;
  --slate-light: #3d5c63;
  --accent:   #c1e8ff;
  --accent-dim: #7bc8f0;
  --accent-bright: #e8f6ff;

  /* Surface colors */
  --surface-0: #00001e;
  --surface-1: #040d2e;
  --surface-2: #081640;
  --surface-3: #0d2054;
  --surface-glass: rgba(26, 63, 117, 0.15);
  --surface-glass-strong: rgba(26, 63, 117, 0.28);

  /* Text */
  --text-primary: #eef4ff;
  --text-secondary: #8faac8;
  --text-muted: #4a6080;
  --text-accent: #c1e8ff;

  /* Borders */
  --border-subtle: rgba(193, 232, 255, 0.08);
  --border-medium: rgba(193, 232, 255, 0.15);
  --border-bright: rgba(193, 232, 255, 0.3);

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.4), 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.5), 0 2px 6px rgba(0,0,42,0.4);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.6), 0 4px 12px rgba(0,0,42,0.5);
  --shadow-glow: 0 0 24px rgba(59,130,212,0.25);
  --shadow-accent: 0 0 32px rgba(193,232,255,0.15);

  /* Spacing */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;
  --space-20: 80px;
  --space-24: 96px;

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-2xl: 32px;
  --radius-full: 9999px;

  /* Typography */
  --font-sans: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'DM Mono', 'SF Mono', monospace;

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out: cubic-bezier(0.45, 0, 0.55, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  --duration-fast: 150ms;
  --duration-base: 250ms;
  --duration-slow: 400ms;
  --duration-xl: 700ms;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: var(--surface-0);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

a {
  color: var(--accent-dim);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out);
}
a:hover { color: var(--accent); }

img, svg { display: block; max-width: 100%; }

button, input, select, textarea {
  font-family: inherit;
  font-size: inherit;
}

/* ─── Scrollbar ─────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--surface-1); }
::-webkit-scrollbar-thumb {
  background: var(--blue-700);
  border-radius: var(--radius-full);
}
::-webkit-scrollbar-thumb:hover { background: var(--blue-500); }

/* ─── Selection ─────────────────────────────────────────── */
::selection {
  background: rgba(193, 232, 255, 0.2);
  color: var(--accent);
}

/* ─── Typography Scale ──────────────────────────────────── */
.display-xl {
  font-size: clamp(3rem, 7vw, 6.5rem);
  font-weight: 300;
  line-height: 1.05;
  letter-spacing: -0.04em;
}
.display-lg {
  font-size: clamp(2.2rem, 5vw, 4.5rem);
  font-weight: 300;
  line-height: 1.1;
  letter-spacing: -0.03em;
}
.display-md {
  font-size: clamp(1.6rem, 3vw, 2.8rem);
  font-weight: 400;
  line-height: 1.15;
  letter-spacing: -0.025em;
}
.heading-lg { font-size: 1.5rem; font-weight: 500; letter-spacing: -0.02em; }
.heading-md { font-size: 1.25rem; font-weight: 500; letter-spacing: -0.015em; }
.heading-sm { font-size: 1rem; font-weight: 600; letter-spacing: -0.01em; }
.body-lg { font-size: 1.125rem; line-height: 1.7; font-weight: 300; }
.body-md { font-size: 1rem; line-height: 1.65; }
.body-sm { font-size: 0.875rem; line-height: 1.6; }
.caption { font-size: 0.75rem; letter-spacing: 0.04em; text-transform: uppercase; }
.mono { font-family: var(--font-mono); }

/* ─── Gradient Text ─────────────────────────────────────── */
.gradient-text {
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-dim) 50%, var(--blue-400) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ─── Buttons ───────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: 12px 24px;
  border-radius: var(--radius-full);
  border: none;
  cursor: pointer;
  font-weight: 500;
  font-size: 0.9375rem;
  transition:
    transform var(--duration-fast) var(--ease-spring),
    box-shadow var(--duration-base) var(--ease-out),
    background var(--duration-fast) var(--ease-out);
  position: relative;
  overflow: hidden;
  white-space: nowrap;
}
.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0);
  transition: background var(--duration-fast) var(--ease-out);
  border-radius: inherit;
}
.btn:hover::after { background: rgba(255,255,255,0.05); }
.btn:active { transform: scale(0.97); }

.btn-primary {
  background: linear-gradient(135deg, var(--blue-500), var(--blue-700));
  color: var(--accent-bright);
  box-shadow: var(--shadow-md), var(--shadow-glow);
}
.btn-primary:hover {
  box-shadow: var(--shadow-lg), 0 0 40px rgba(59,130,212,0.4);
  transform: translateY(-1px);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border-medium);
}
.btn-ghost:hover {
  border-color: var(--border-bright);
  color: var(--text-primary);
}

.btn-accent {
  background: linear-gradient(135deg, rgba(193,232,255,0.15), rgba(193,232,255,0.08));
  color: var(--accent);
  border: 1px solid var(--border-bright);
  backdrop-filter: blur(8px);
}
.btn-accent:hover {
  background: linear-gradient(135deg, rgba(193,232,255,0.22), rgba(193,232,255,0.12));
  box-shadow: var(--shadow-accent);
}

.btn-sm { padding: 8px 16px; font-size: 0.8125rem; }
.btn-lg { padding: 16px 36px; font-size: 1.0625rem; }
.btn-icon {
  padding: 10px;
  border-radius: var(--radius-md);
  width: 40px;
  height: 40px;
  justify-content: center;
}

/* ─── Glass Card ────────────────────────────────────────── */
.glass {
  background: var(--surface-glass);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
}
.glass-strong {
  background: var(--surface-glass-strong);
  backdrop-filter: blur(32px) saturate(200%);
  -webkit-backdrop-filter: blur(32px) saturate(200%);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-xl);
}

/* ─── Form Controls ─────────────────────────────────────── */
.input-field {
  width: 100%;
  padding: 12px 16px;
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 0.9375rem;
  transition:
    border-color var(--duration-fast) var(--ease-out),
    box-shadow var(--duration-fast) var(--ease-out),
    background var(--duration-fast) var(--ease-out);
  outline: none;
}
.input-field:focus {
  border-color: var(--blue-400);
  background: rgba(255,255,255,0.06);
  box-shadow: 0 0 0 3px rgba(59,130,212,0.15);
}
.input-field::placeholder { color: var(--text-muted); }

.label {
  display: block;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-secondary);
  letter-spacing: 0.02em;
  margin-bottom: var(--space-2);
}

/* Range slider */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 4px;
  background: var(--surface-3);
  border-radius: var(--radius-full);
  outline: none;
  cursor: pointer;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  background: linear-gradient(135deg, var(--blue-400), var(--accent-dim));
  border-radius: 50%;
  box-shadow: 0 2px 8px rgba(0,0,0,0.4);
  transition: transform var(--duration-fast) var(--ease-spring);
  cursor: grab;
}
input[type="range"]::-webkit-slider-thumb:active {
  transform: scale(1.3);
  cursor: grabbing;
}
input[type="range"]::-moz-range-thumb {
  width: 18px; height: 18px;
  background: linear-gradient(135deg, var(--blue-400), var(--accent-dim));
  border-radius: 50%;
  border: none;
  cursor: grab;
}

/* Color picker */
input[type="color"] {
  -webkit-appearance: none;
  appearance: none;
  width: 40px;
  height: 40px;
  border: 2px solid var(--border-medium);
  border-radius: var(--radius-md);
  background: transparent;
  cursor: pointer;
  padding: 2px;
  transition: border-color var(--duration-fast) var(--ease-out);
}
input[type="color"]:hover { border-color: var(--border-bright); }
input[type="color"]::-webkit-color-swatch-wrapper { padding: 0; }
input[type="color"]::-webkit-color-swatch {
  border: none;
  border-radius: calc(var(--radius-md) - 4px);
}

/* Select */
select.input-field {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3E%3Cpath fill='%238faac8' d='M4.5 6l3.5 3.5L11.5 6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
}

/* ─── Divider ───────────────────────────────────────────── */
.divider {
  height: 1px;
  background: var(--border-subtle);
  margin: var(--space-6) 0;
}

/* ─── Badge ─────────────────────────────────────────────── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 4px 10px;
  border-radius: var(--radius-full);
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.badge-blue {
  background: rgba(59,130,212,0.15);
  color: var(--accent-dim);
  border: 1px solid rgba(59,130,212,0.25);
}

/* ─── Nav ───────────────────────────────────────────────── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: 64px;
  display: flex;
  align-items: center;
  padding: 0 var(--space-8);
  background: rgba(0,0,30,0.7);
  backdrop-filter: blur(24px) saturate(180%);
  -webkit-backdrop-filter: blur(24px) saturate(180%);
  border-bottom: 1px solid var(--border-subtle);
  transition: background var(--duration-slow) var(--ease-out);
}
.nav-inner {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
}
.nav-logo-mark {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--blue-500), var(--blue-700));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-glow);
}
.nav-logo-text {
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}
.nav-link {
  padding: 8px 14px;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition:
    color var(--duration-fast) var(--ease-out),
    background var(--duration-fast) var(--ease-out);
}
.nav-link:hover {
  color: var(--text-primary);
  background: rgba(255,255,255,0.05);
}
.nav-link.active { color: var(--accent); }

/* ─── Animated Background ───────────────────────────────── */
.bg-mesh {
  position: fixed;
  inset: 0;
  z-index: -1;
  overflow: hidden;
  pointer-events: none;
}
.bg-mesh::before {
  content: '';
  position: absolute;
  width: 120vmax;
  height: 120vmax;
  top: -40vmax;
  left: -20vmax;
  background: radial-gradient(ellipse at 30% 30%, rgba(26,63,117,0.22) 0%, transparent 60%),
              radial-gradient(ellipse at 70% 70%, rgba(45,74,80,0.18) 0%, transparent 60%),
              radial-gradient(ellipse at 50% 10%, rgba(59,130,212,0.1) 0%, transparent 50%);
  animation: meshDrift 25s ease-in-out infinite alternate;
}
.bg-mesh::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 80% 20%, rgba(193,232,255,0.04) 0%, transparent 45%);
  animation: meshDrift2 18s ease-in-out infinite alternate;
}
@keyframes meshDrift {
  from { transform: translate(0,0) rotate(0deg); }
  to   { transform: translate(3vw, 2vh) rotate(3deg); }
}
@keyframes meshDrift2 {
  from { transform: translate(0,0); }
  to   { transform: translate(-2vw, 3vh); }
}

/* ─── Page Enter Animation ──────────────────────────────── */
.page-enter {
  animation: pageEnter var(--duration-xl) var(--ease-out) forwards;
}
@keyframes pageEnter {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}
.fade-in-up {
  opacity: 0;
  animation: pageEnter var(--duration-xl) var(--ease-out) forwards;
}
.delay-1 { animation-delay: 100ms; }
.delay-2 { animation-delay: 200ms; }
.delay-3 { animation-delay: 350ms; }
.delay-4 { animation-delay: 500ms; }
.delay-5 { animation-delay: 650ms; }

/* ─── Footer ────────────────────────────────────────────── */
.footer {
  border-top: 1px solid var(--border-subtle);
  padding: var(--space-10) var(--space-8);
  margin-top: auto;
}
.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
  flex-wrap: wrap;
}
.footer-copy {
  font-size: 0.8125rem;
  color: var(--text-muted);
}
.footer-github {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: 0.8125rem;
  color: var(--text-secondary);
  padding: 8px 14px;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  transition:
    color var(--duration-fast) var(--ease-out),
    border-color var(--duration-fast) var(--ease-out),
    box-shadow var(--duration-fast) var(--ease-out);
}
.footer-github:hover {
  color: var(--text-primary);
  border-color: var(--border-bright);
  box-shadow: var(--shadow-glow);
}

/* ─── Utility ───────────────────────────────────────────── */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
}
.flex { display: flex; }
.flex-col { display: flex; flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.w-full { width: 100%; }
.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.text-secondary { color: var(--text-secondary); }
.text-accent { color: var(--accent); }
.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.pt-nav { padding-top: 64px; }

/* ─── Responsive ────────────────────────────────────────── */
@media (max-width: 768px) {
  .nav { padding: 0 var(--space-4); }
  .nav-links .btn:not(.nav-link) { display: none; }
  .footer-inner { flex-direction: column; text-align: center; }
}
@media (max-width: 480px) {
  :root {
    --space-8: 20px;
    --space-10: 32px;
    --space-12: 40px;
  }
}