/* ==========================================================================
   Gostack — brand tokens
   Mood: midnight engineering workshop. Oxidized-teal console light, copper
   verdigris accent. Committed dark strategy; the teal carries identity.
   ========================================================================== */

:root {
  /* surfaces */
  --bg:          oklch(0.165 0.018 174);
  --bg-elev:     oklch(0.195 0.020 174);
  --surface:     oklch(0.230 0.024 174);
  --surface-2:   oklch(0.270 0.028 174);
  --line:        oklch(0.320 0.028 174);
  --line-soft:   oklch(0.260 0.022 174);

  /* ink */
  --ink:         oklch(0.960 0.006 174);
  --muted:       oklch(0.745 0.018 174);
  --faint:       oklch(0.560 0.020 174);

  /* brand */
  --primary:     oklch(0.640 0.120 174);
  --primary-strong: oklch(0.560 0.145 174);
  --primary-deep:   oklch(0.420 0.110 174);
  --accent:      oklch(0.760 0.130 47);
  --accent-soft: oklch(0.720 0.090 47);

  /* type */
  --font-display: "Space Grotesk", "Inter", system-ui, sans-serif;
  --font-body:    "Inter", system-ui, -apple-system, sans-serif;
  --font-mono:    "JetBrains Mono", ui-monospace, "SFMono-Regular", monospace;

  /* shape */
  --radius: 14px;
  --radius-sm: 8px;
  --radius-pill: 999px;

  /* layout */
  --maxw: 1240px;
  --gutter: clamp(1.25rem, 4vw, 2.5rem);

  /* ease */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-out-quart: cubic-bezier(0.25, 1, 0.5, 1);
}

/* ==========================================================================
   Reset
   ========================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: clamp(1rem, 0.96rem + 0.2vw, 1.0625rem);
  line-height: 1.6;
  color: var(--ink);
  background-color: var(--bg);
  background-image:
    radial-gradient(120% 80% at 80% -10%, oklch(0.30 0.06 174 / 0.35), transparent 60%),
    radial-gradient(90% 60% at 0% 10%, oklch(0.36 0.05 47 / 0.10), transparent 55%);
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

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

a { color: inherit; text-decoration: none; }

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

::selection { background: var(--primary); color: var(--bg); }

:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ==========================================================================
   Layout primitives
   ========================================================================== */

.wrap {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section {
  padding-block: clamp(4.5rem, 9vw, 8rem);
  position: relative;
}

.section--tight { padding-block: clamp(3rem, 6vw, 5rem); }

.divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line) 20%, var(--line) 80%, transparent);
  border: 0;
  margin: 0;
}

/* ==========================================================================
   Type
   ========================================================================== */

.display {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.02;
  letter-spacing: -0.025em;
  text-wrap: balance;
  margin: 0;
}

.display--xl { font-size: clamp(2.6rem, 1.4rem + 5.4vw, 5.4rem); }
.display--lg { font-size: clamp(2.1rem, 1.3rem + 3.6vw, 3.6rem); }
.display--md { font-size: clamp(1.6rem, 1.1rem + 2.2vw, 2.4rem); }

.lead {
  font-size: clamp(1.05rem, 1rem + 0.4vw, 1.3rem);
  line-height: 1.55;
  color: var(--muted);
  max-width: 62ch;
  text-wrap: pretty;
}

.prose { max-width: 68ch; }
.prose p { color: var(--muted); }

.mono {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.04em;
  color: var(--faint);
  text-transform: uppercase;
}

/* ==========================================================================
   Nav
   ========================================================================== */

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(12px);
  background: oklch(0.165 0.018 174 / 0.72);
  border-bottom: 1px solid transparent;
  transition: border-color 0.4s var(--ease-out), background 0.4s var(--ease-out);
}

.nav--scrolled {
  border-bottom-color: var(--line-soft);
  background: oklch(0.165 0.018 174 / 0.88);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  height: 72px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
}

.brand__mark { width: 30px; height: 30px; flex: none; }

.nav__links {
  display: flex;
  align-items: center;
  gap: 2rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav__links a {
  font-size: 0.9375rem;
  color: var(--muted);
  transition: color 0.2s var(--ease-out);
  position: relative;
}

.nav__links a:hover { color: var(--ink); }

.nav__cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.nav__burger {
  display: none;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line);
  align-items: center;
  justify-content: center;
}

.nav__burger span,
.nav__burger span::before,
.nav__burger span::after {
  content: "";
  display: block;
  width: 18px;
  height: 1.5px;
  background: var(--ink);
  border-radius: 2px;
  transition: transform 0.3s var(--ease-out);
}
.nav__burger span::before { transform: translateY(-5px); position: absolute; }
.nav__burger span::after  { transform: translateY(5px); position: absolute; }

/* ==========================================================================
   Buttons
   ========================================================================== */

.btn {
  --btn-bg: var(--primary);
  --btn-fg: var(--bg);
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.8rem 1.4rem;
  border-radius: var(--radius-pill);
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: -0.005em;
  background: var(--btn-bg);
  color: var(--btn-fg);
  border: 1px solid transparent;
  transition: transform 0.25s var(--ease-out), background 0.25s var(--ease-out), border-color 0.25s var(--ease-out);
  will-change: transform;
}

.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }

.btn--primary {
  --btn-bg: var(--primary);
  --btn-fg: oklch(0.14 0.02 174);
}

.btn--primary:hover { background: var(--primary-strong); }

.btn--ghost {
  --btn-bg: transparent;
  --btn-fg: var(--ink);
  border-color: var(--line);
}

.btn--ghost:hover { border-color: var(--primary); background: oklch(0.23 0.024 174 / 0.6); }

.btn .arrow { transition: transform 0.25s var(--ease-out); }
.btn:hover .arrow { transform: translateX(3px); }

/* ==========================================================================
   Hero
   ========================================================================== */

.hero {
  position: relative;
  padding-top: clamp(3rem, 7vw, 6rem);
  padding-bottom: clamp(4rem, 8vw, 7rem);
  overflow: hidden;
}

.hero__grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: clamp(2rem, 5vw, 4rem);
  align-items: center;
}

.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-pill);
  border: 1px solid var(--line);
  background: oklch(0.23 0.024 174 / 0.5);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  color: var(--muted);
  text-transform: uppercase;
}

.hero__eyebrow .dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--primary);
  box-shadow: 0 0 0 4px oklch(0.64 0.12 174 / 0.18);
  animation: pulse 2.6s var(--ease-out) infinite;
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 oklch(0.64 0.12 174 / 0.35); }
  50% { box-shadow: 0 0 0 6px oklch(0.64 0.12 174 / 0); }
}

.hero__title { margin-top: 1.6rem; }

.hero__title em {
  font-style: normal;
  color: var(--primary);
}

.hero__sub {
  margin-top: 1.6rem;
  max-width: 54ch;
}

.hero__actions {
  margin-top: 2.2rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
}

.hero__meta {
  margin-top: 2.6rem;
  display: flex;
  gap: clamp(1.5rem, 4vw, 3rem);
  flex-wrap: wrap;
  color: var(--muted);
  font-size: 0.9rem;
}

.hero__meta strong {
  display: block;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.5rem;
  color: var(--ink);
  letter-spacing: -0.02em;
}

.hero__meta span { font-family: var(--font-mono); font-size: 0.78rem; color: var(--faint); text-transform: uppercase; letter-spacing: 0.05em; }

/* hero stack visual */
.stack {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  max-width: 460px;
  margin-inline: auto;
  perspective: 1200px;
  perspective-origin: 50% 40%;
}

.stack__scene {
  position: absolute;
  inset: 0;
  transform-style: preserve-3d;
  transform: rotateX(52deg) rotateZ(-32deg);
}

.stack__layer {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 62%;
  aspect-ratio: 1.55 / 1;
  border-radius: 12px;
  transform: translate(-50%, -50%) translateZ(var(--z, 0px));
  background: var(--surface);
  border: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  box-shadow: 0 30px 60px -30px oklch(0.10 0.02 174 / 0.8);
  transition: transform 0.6s var(--ease-out), box-shadow 0.6s var(--ease-out);
}

.stack__layer--accent {
  background: var(--primary-deep);
  border-color: var(--primary);
  color: oklch(0.92 0.02 174);
}

.stack__layer--copper {
  background: oklch(0.42 0.10 47);
  border-color: var(--accent-soft);
  color: oklch(0.93 0.03 47);
}

.stack:hover .stack__layer { transform: translate(-50%, -50%) translateZ(var(--z, 0px)) translateY(-6px); }

.stack__glow {
  position: absolute;
  inset: 15%;
  border-radius: 50%;
  background: radial-gradient(circle, oklch(0.64 0.12 174 / 0.35), transparent 65%);
  filter: blur(40px);
  transform: translateZ(-80px);
  z-index: -1;
}

/* ==========================================================================
   Capabilities — editorial definition list, not identical cards
   ========================================================================== */

.cap__head {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  max-width: 60ch;
  margin-bottom: clamp(2.5rem, 5vw, 4rem);
}

.cap__list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line-soft);
}

.cap__item {
  display: grid;
  grid-template-columns: 0.5fr 1fr 2fr;
  gap: clamp(1rem, 3vw, 2.5rem);
  align-items: baseline;
  padding: clamp(1.4rem, 2.6vw, 2rem) 0;
  border-bottom: 1px solid var(--line-soft);
  transition: background 0.3s var(--ease-out);
}

.cap__item:hover { background: oklch(0.23 0.024 174 / 0.35); }

.cap__num {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--faint);
  letter-spacing: 0.06em;
}

.cap__name {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.05rem, 1rem + 0.5vw, 1.3rem);
  letter-spacing: -0.015em;
  color: var(--ink);
}

.cap__desc { color: var(--muted); line-height: 1.55; }

.cap__item:hover .cap__name { color: var(--primary); }

/* ==========================================================================
   Approach — real numbered sequence
   ========================================================================== */

.approach__head {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(2rem, 5vw, 4rem);
  align-items: end;
  margin-bottom: clamp(2.5rem, 5vw, 4rem);
}

.approach__steps {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  overflow: hidden;
}

.step {
  background: var(--bg);
  padding: clamp(1.6rem, 3vw, 2.4rem);
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  transition: background 0.3s var(--ease-out);
}

.step:hover { background: var(--bg-elev); }

.step__num {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  letter-spacing: 0.08em;
}

.step__title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.15rem, 1rem + 0.6vw, 1.45rem);
  letter-spacing: -0.015em;
}

.step__body { color: var(--muted); }

/* ==========================================================================
   Principles band
   ========================================================================== */

.principles {
  background: var(--bg-elev);
  border-block: 1px solid var(--line-soft);
}

.principles__grid {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: clamp(2rem, 5vw, 4rem);
  align-items: center;
}

.principles__words {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.4rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.4rem, 1rem + 1.8vw, 2.2rem);
  letter-spacing: -0.02em;
}

.principles__words span:nth-child(1) { color: var(--ink); }
.principles__words span:nth-child(2) { color: var(--primary); }
.principles__words span:nth-child(3) { color: var(--accent); }
.principles__words span:nth-child(4) { color: var(--muted); font-size: 0.6em; font-weight: 500; }

.principles__note { color: var(--muted); max-width: 56ch; }

/* ==========================================================================
   CTA / contact
   ========================================================================== */

.cta {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background:
    radial-gradient(120% 120% at 100% 0%, oklch(0.42 0.11 174 / 0.35), transparent 55%),
    var(--surface);
  padding: clamp(2.5rem, 5vw, 4rem);
}

.cta__grid {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: clamp(2rem, 5vw, 3.5rem);
  align-items: center;
}

.cta__form { display: grid; gap: 0.85rem; }

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.field label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--faint);
}

.field input,
.field textarea {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 0.7rem 0.9rem;
  color: var(--ink);
  font: inherit;
  font-size: 0.95rem;
  transition: border-color 0.2s var(--ease-out);
}

.field input::placeholder,
.field textarea::placeholder { color: var(--faint); }

.field input:focus,
.field textarea:focus {
  outline: none;
  border-color: var(--primary);
}

.field textarea { resize: vertical; min-height: 96px; }

.cta__form .btn { justify-self: start; margin-top: 0.4rem; }

/* ==========================================================================
   Footer
   ========================================================================== */

.footer {
  padding-block: clamp(3rem, 6vw, 4.5rem) clamp(2rem, 4vw, 3rem);
  border-top: 1px solid var(--line-soft);
}

.footer__grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: clamp(2rem, 5vw, 3rem);
  margin-bottom: clamp(2.5rem, 5vw, 3.5rem);
}

.footer__about p { color: var(--muted); max-width: 38ch; margin-top: 1rem; }

.footer__col h4 {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--faint);
  margin: 0 0 1rem;
  font-weight: 500;
}

.footer__col ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.6rem; }
.footer__col a { color: var(--muted); font-size: 0.9375rem; transition: color 0.2s var(--ease-out); }
.footer__col a:hover { color: var(--ink); }

.footer__base {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  padding-top: 1.8rem;
  border-top: 1px solid var(--line-soft);
  color: var(--faint);
  font-size: 0.85rem;
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

/* ==========================================================================
   Reveal on scroll
   ========================================================================== */

[data-reveal] {
  opacity: 1;
  transform: none;
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
  transform: translateY(18px);
  opacity: 0;
}

[data-reveal].is-in {
  opacity: 1;
  transform: none;
}

[data-reveal][data-stagger] > * {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.6s var(--ease-out), transform 0.6s var(--ease-out);
}

[data-reveal][data-stagger].is-in > * {
  opacity: 1;
  transform: none;
}

[data-reveal][data-stagger].is-in > *:nth-child(1) { transition-delay: 0.05s; }
[data-reveal][data-stagger].is-in > *:nth-child(2) { transition-delay: 0.12s; }
[data-reveal][data-stagger].is-in > *:nth-child(3) { transition-delay: 0.19s; }
[data-reveal][data-stagger].is-in > *:nth-child(4) { transition-delay: 0.26s; }
[data-reveal][data-stagger].is-in > *:nth-child(5) { transition-delay: 0.33s; }
[data-reveal][data-stagger].is-in > *:nth-child(6) { transition-delay: 0.40s; }
[data-reveal][data-stagger].is-in > *:nth-child(7) { transition-delay: 0.47s; }
[data-reveal][data-stagger].is-in > *:nth-child(8) { transition-delay: 0.54s; }

@media (prefers-reduced-motion: reduce) {
  [data-reveal], [data-reveal][data-stagger] > * {
    opacity: 1 !important;
    transform: none !important;
    transition: none !important;
  }
  .hero__eyebrow .dot { animation: none; }
}

/* ==========================================================================
   Responsive
   ========================================================================== */

@media (max-width: 920px) {
  .hero__grid { grid-template-columns: 1fr; }
  .stack { max-width: 360px; order: 2; margin-top: 2rem; }
  .approach__head { grid-template-columns: 1fr; align-items: start; }
  .principles__grid { grid-template-columns: 1fr; }
  .cta__grid { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr 1fr; }
  .footer__about { grid-column: 1 / -1; }
}

@media (max-width: 680px) {
  .nav__links { display: none; }
  .nav__burger { display: inline-flex; }
  .nav__cta .btn { display: none; }
  .cap__item { grid-template-columns: 1fr; gap: 0.4rem; }
  .cap__num { order: 2; }
  .approach__steps { grid-template-columns: 1fr; }
  .hero__meta { gap: 1.5rem; }
  .footer__grid { grid-template-columns: 1fr; }
  .footer__base { flex-direction: column; align-items: flex-start; }
}

/* mobile menu */
.mobile-menu {
  position: fixed;
  inset: 72px 0 auto 0;
  background: var(--bg);
  border-bottom: 1px solid var(--line-soft);
  padding: 1.5rem var(--gutter) 2rem;
  transform: translateY(-12px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s var(--ease-out), transform 0.3s var(--ease-out);
  z-index: 49;
}
.mobile-menu.is-open { opacity: 1; transform: none; pointer-events: auto; }
.mobile-menu ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.4rem; }
.mobile-menu a { display: block; padding: 0.7rem 0; font-size: 1.1rem; color: var(--ink); }