/* =========================================================
   Knowtifyi — Design System
   Aesthetic: editorial-tech, engineering-journal,
   refined dark theme with electric chartreuse accent.
   ========================================================= */

@import url('https://fonts.googleapis.com/css2?family=Fraunces:opsz,wght@9..144,300;9..144,400;9..144,500;9..144,600;9..144,700&family=JetBrains+Mono:wght@300;400;500;600&family=Inter+Tight:wght@300;400;500;600;700&display=swap');

:root {
  /* Color tokens */
  --ink-950: #0a0e14;
  --ink-900: #0f141c;
  --ink-800: #161c26;
  --ink-700: #1f2733;
  --ink-600: #2a3340;
  --ink-500: #3a4554;
  --ink-400: #5a6678;
  --ink-300: #8a95a8;
  --ink-200: #b8c1d0;
  --ink-100: #e4e8f0;
  --ink-50:  #f4f6fa;
  --paper:   #f9f7f2;

  --accent:        #c8f04c;   /* electric chartreuse */
  --accent-dim:    #9bc02e;
  --accent-glow:   rgba(200, 240, 76, 0.18);
  --warn:          #ff8a4c;
  --danger:        #f25c5c;
  --ok:            #5cdba0;

  /* Type */
  --font-display: 'Fraunces', Georgia, serif;
  --font-body:    'Inter Tight', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono:    'JetBrains Mono', 'SFMono-Regular', Menlo, monospace;

  /* Geometry */
  --radius-sm: 4px;
  --radius:    8px;
  --radius-lg: 16px;
  --gutter:    clamp(1.25rem, 3vw, 2rem);
  --maxw:      1240px;

  --shadow-1: 0 1px 0 rgba(255,255,255,0.04) inset, 0 1px 2px rgba(0,0,0,0.4);
  --shadow-2: 0 20px 60px -20px rgba(0,0,0,0.6);
}

*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--ink-950);
  color: var(--ink-100);
  line-height: 1.55;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

/* Atmospheric background — subtle grid + radial glow */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.018) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.018) 1px, transparent 1px);
  background-size: 48px 48px;
  pointer-events: none;
  z-index: 0;
  mask-image: radial-gradient(ellipse at top, black 30%, transparent 80%);
}

body::after {
  content: "";
  position: fixed;
  top: -200px; right: -200px;
  width: 600px; height: 600px;
  background: radial-gradient(circle, var(--accent-glow), transparent 60%);
  filter: blur(40px);
  pointer-events: none;
  z-index: 0;
}

main, header, footer, nav { position: relative; z-index: 1; }

/* Typography */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 500;
  letter-spacing: -0.02em;
  line-height: 1.05;
  margin: 0 0 0.6em;
  color: var(--ink-50);
}

h1 { font-size: clamp(2.5rem, 6vw, 4.75rem); font-weight: 400; }
h2 { font-size: clamp(1.875rem, 4vw, 2.75rem); }
h3 { font-size: clamp(1.25rem, 2.4vw, 1.625rem); font-weight: 600; }
h4 { font-size: 1.05rem; font-weight: 600; letter-spacing: 0; }

p { margin: 0 0 1em; color: var(--ink-200); max-width: 65ch; }

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 120ms;
}
a:hover { color: var(--ink-50); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1rem;
}
.eyebrow::before {
  content: "";
  width: 24px;
  height: 1px;
  background: var(--accent);
}

.mono { font-family: var(--font-mono); }
.serif { font-family: var(--font-display); font-style: italic; }

/* Container */
.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

/* Header / Nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(14px);
  background: rgba(10, 14, 20, 0.7);
  border-bottom: 1px solid var(--ink-700);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.1rem 0;
  gap: 2rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-family: var(--font-display);
  font-weight: 500;
  font-size: 1.25rem;
  color: var(--ink-50);
  letter-spacing: -0.02em;
}
.brand:hover { color: var(--ink-50); }

.brand-mark {
  width: 38px;
  height: 38px;
  display: inline-grid;
  place-items: center;
  border: 1px solid var(--accent);
  border-radius: 6px;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  background: var(--accent-glow);
}

.nav-links {
  display: flex;
  gap: 1.7rem;
  list-style: none;
  margin: 0; padding: 0;
  align-items: center;
}
.nav-links a {
  color: var(--ink-200);
  font-size: 0.9rem;
  font-weight: 500;
  position: relative;
  padding: 0.3rem 0;
}
.nav-links a:hover { color: var(--ink-50); }
.nav-links a.active { color: var(--accent); }
.nav-links a.active::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -4px;
  height: 2px;
  background: var(--accent);
}
.nav-links a.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--accent);
  color: var(--ink-950);
  padding: 0.6rem 1.1rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.9rem;
  border: 1px solid var(--accent);
  transition: transform 150ms, box-shadow 150ms;
}
.nav-links a.nav-cta:hover {
  color: var(--ink-950);
  transform: translateY(-1px);
  box-shadow: 0 8px 24px -8px var(--accent);
}
.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--ink-600);
  color: var(--ink-100);
  border-radius: 6px;
  padding: 0.45rem 0.6rem;
  cursor: pointer;
}

/* Sections */
.section {
  padding: clamp(4rem, 9vw, 7rem) 0;
  position: relative;
}
.section-tight { padding: clamp(3rem, 6vw, 5rem) 0; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.85rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  cursor: pointer;
  font-family: var(--font-body);
  transition: all 150ms;
  text-decoration: none;
}
.btn-primary {
  background: var(--accent);
  color: var(--ink-950);
  border-color: var(--accent);
}
.btn-primary:hover {
  color: var(--ink-950);
  transform: translateY(-1px);
  box-shadow: 0 10px 30px -10px var(--accent);
}
.btn-ghost {
  background: transparent;
  color: var(--ink-100);
  border-color: var(--ink-600);
}
.btn-ghost:hover {
  color: var(--ink-50);
  border-color: var(--ink-400);
  background: var(--ink-800);
}

/* Cards */
.card {
  background: linear-gradient(180deg, var(--ink-800), var(--ink-900));
  border: 1px solid var(--ink-700);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  position: relative;
  transition: border-color 200ms, transform 200ms;
}
.card:hover {
  border-color: var(--ink-500);
  transform: translateY(-2px);
}

.card-corner {
  position: absolute;
  top: 14px; right: 14px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--ink-400);
  letter-spacing: 0.1em;
}

/* Grid utilities */
.grid { display: grid; gap: 1.5rem; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 900px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .nav-links { display: none; }
  .nav-toggle { display: inline-flex; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%; left: 0; right: 0;
    background: var(--ink-900);
    border-bottom: 1px solid var(--ink-700);
    padding: 1.5rem var(--gutter);
    gap: 1rem;
    align-items: flex-start;
  }
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--ink-700);
  background: var(--ink-900);
  padding: 4rem 0 2rem;
  margin-top: 4rem;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1fr;
  gap: 2.5rem;
}
.footer-grid h4 {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-400);
  margin-bottom: 1rem;
}
.footer-grid ul {
  list-style: none;
  padding: 0; margin: 0;
  display: flex; flex-direction: column;
  gap: 0.55rem;
}
.footer-grid a {
  color: var(--ink-200);
  font-size: 0.92rem;
}
.footer-grid a:hover { color: var(--accent); }
.footer-bottom {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--ink-800);
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-400);
}
@media (max-width: 800px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .footer-bottom { flex-direction: column; gap: 0.6rem; }
}

/* Forms */
.field { margin-bottom: 1.25rem; }
.field label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-300);
  margin-bottom: 0.45rem;
}
.field input,
.field select,
.field textarea {
  width: 100%;
  background: var(--ink-900);
  border: 1px solid var(--ink-600);
  border-radius: var(--radius);
  padding: 0.85rem 1rem;
  color: var(--ink-50);
  font-family: var(--font-body);
  font-size: 0.95rem;
  transition: border-color 150ms, box-shadow 150ms;
}
.field input:focus,
.field select:focus,
.field textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}
.field textarea { min-height: 140px; resize: vertical; }

.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
@media (max-width: 600px) { .form-row { grid-template-columns: 1fr; } }

/* Tag / Pills */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.3rem 0.65rem;
  background: var(--ink-800);
  border: 1px solid var(--ink-600);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  color: var(--ink-200);
}
.tag.accent {
  background: var(--accent-glow);
  color: var(--accent);
  border-color: var(--accent);
}

/* Animated reveal */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 700ms ease, transform 700ms cubic-bezier(0.16, 1, 0.3, 1);
}
.reveal.in {
  opacity: 1;
  transform: none;
}

/* Page intro block (used on inner pages) */
.page-intro {
  padding: clamp(4rem, 9vw, 7rem) 0 clamp(2rem, 4vw, 3rem);
  border-bottom: 1px solid var(--ink-800);
}
.page-intro h1 { max-width: 18ch; }
.page-intro p { font-size: 1.1rem; max-width: 60ch; color: var(--ink-300); }

/* Code-style accent block */
.code-line {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.4rem 0.7rem;
  background: var(--ink-800);
  border: 1px solid var(--ink-700);
  border-radius: 6px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-200);
}
.code-line .dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 8px var(--accent);
}

/* Utility */
.center { text-align: center; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mt-6 { margin-top: 3rem; }
.text-dim { color: var(--ink-300); }
.divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--ink-600), transparent);
  margin: 3rem 0;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}