/* =========================================================================
   Robonaut Labs — design system
   Dependency-free. Dark, sovereign, operator-grade.
   ========================================================================= */

:root {
  color-scheme: dark;

  /* Palette */
  --ink: #f8fbff;
  --muted: #aeb8c7;
  --faint: #7e8aa0;
  --line: rgba(255, 255, 255, 0.1);
  --line-strong: rgba(255, 255, 255, 0.18);
  --gold: #f2cb8a;
  --gold-soft: rgba(242, 203, 138, 0.14);
  --steel: #8fb5d9;
  --steel-soft: rgba(143, 181, 217, 0.12);
  --night: #05070c;
  --surface: rgba(255, 255, 255, 0.022);
  --surface-2: rgba(255, 255, 255, 0.04);
  --surface-alt: #070b13;

  /* Type scale (fluid) */
  --step--1: clamp(0.82rem, 0.78rem + 0.2vw, 0.92rem);
  --step-0: clamp(1rem, 0.96rem + 0.25vw, 1.12rem);
  --step-1: clamp(1.18rem, 1.08rem + 0.5vw, 1.45rem);
  --step-2: clamp(1.5rem, 1.3rem + 1vw, 2.1rem);
  --step-3: clamp(2rem, 1.6rem + 2vw, 3rem);
  --step-4: clamp(2.7rem, 1.9rem + 4vw, 5rem);

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 0.85rem;
  --space-md: 1.35rem;
  --space-lg: 2.2rem;
  --space-xl: clamp(3.5rem, 6vw, 6.5rem);

  /* Geometry */
  --container: 1120px;
  --container-narrow: 760px;
  --radius: 14px;
  --radius-lg: 22px;
  --radius-pill: 999px;
  --header-h: 4.5rem;

  --shadow: 0 24px 60px -28px rgba(0, 0, 0, 0.8);
  --transition: 180ms cubic-bezier(0.4, 0, 0.2, 1);

  --font: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

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

html {
  min-height: 100%;
  background: var(--night);
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 1rem);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  font-size: var(--step-0);
  line-height: 1.6;
  color: var(--ink);
  background:
    radial-gradient(circle at 50% -8%, rgba(143, 181, 217, 0.12), transparent 34rem),
    radial-gradient(circle at 90% 0%, rgba(242, 203, 138, 0.06), transparent 26rem),
    linear-gradient(160deg, #020306 0%, #07101b 46%, #060810 100%);
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img {
  max-width: 100%;
  height: auto;
}

h1,
h2,
h3 {
  margin: 0;
  font-weight: 650;
  letter-spacing: -0.02em;
  line-height: 1.08;
}

p {
  margin: 0;
}

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

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

:focus-visible {
  outline: 2px solid var(--gold);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ---------- Utilities ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: clamp(1.15rem, 4vw, 2.5rem);
}

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

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  border: 0;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  overflow: hidden;
  white-space: nowrap;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -3rem;
  z-index: 100;
  padding: 0.6rem 1rem;
  border-radius: var(--radius);
  background: var(--ink);
  color: var(--night);
  font-weight: 600;
  transition: top var(--transition);
}

.skip-link:focus {
  top: 1rem;
}

/* ---------- Buttons ---------- */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.78rem 1.4rem;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-size: var(--step--1);
  font-weight: 600;
  letter-spacing: 0.01em;
  white-space: nowrap;
  cursor: pointer;
  transition: transform var(--transition), background var(--transition),
    border-color var(--transition), color var(--transition);
}

.button--primary {
  background: linear-gradient(180deg, #f7d8a2, var(--gold));
  color: #2a1c06;
  box-shadow: 0 12px 30px -14px rgba(242, 203, 138, 0.7);
}

.button--primary:hover {
  transform: translateY(-1px);
  background: linear-gradient(180deg, #fbe3b6, #f4d199);
}

.button--ghost {
  border-color: var(--line-strong);
  color: var(--ink);
  background: var(--surface);
}

.button--ghost:hover {
  border-color: var(--steel);
  background: var(--steel-soft);
}

.button--sm {
  padding: 0.55rem 1.05rem;
}

.button--lg {
  padding: 0.95rem 1.8rem;
  font-size: var(--step-0);
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(5, 7, 12, 0.72);
  backdrop-filter: saturate(140%) blur(14px);
  border-bottom: 1px solid var(--line);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: var(--header-h);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  font-weight: 600;
}

.brand__mark {
  width: 1.1rem;
  height: 1.1rem;
  flex: none;
  border-radius: 4px;
  background: linear-gradient(135deg, var(--gold), var(--steel));
  transform: rotate(45deg);
  box-shadow: 0 0 18px -2px rgba(242, 203, 138, 0.5);
}

.brand__word {
  font-size: 1.06rem;
  letter-spacing: -0.01em;
}

.brand__word-accent {
  margin-left: 0.32em;
  color: var(--gold);
}

/* ---------- Navigation ---------- */
.site-nav {
  display: flex;
  align-items: center;
}

.nav-toggle-input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.nav-toggle {
  display: none;
  width: 2.75rem;
  height: 2.75rem;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--surface);
  cursor: pointer;
  align-items: center;
  justify-content: center;
}

.nav-toggle__bars,
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  display: block;
  width: 1.1rem;
  height: 2px;
  border-radius: 2px;
  background: var(--ink);
  transition: transform var(--transition), opacity var(--transition);
}

.nav-toggle__bars {
  position: relative;
}

.nav-toggle__bars::before {
  position: absolute;
  top: -0.4rem;
}

.nav-toggle__bars::after {
  position: absolute;
  top: 0.4rem;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: clamp(1rem, 2.2vw, 2rem);
}

.nav-menu a:not(.button) {
  font-size: var(--step--1);
  font-weight: 500;
  color: var(--muted);
  transition: color var(--transition);
}

.nav-menu a:not(.button):hover {
  color: var(--ink);
}

.nav-menu__cta {
  margin-left: 0.4rem;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  padding-top: clamp(3.5rem, 9vw, 7rem);
  padding-bottom: clamp(3.5rem, 9vw, 7rem);
  text-align: center;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--gold), transparent);
  opacity: 0.5;
}

.hero__inner {
  max-width: 880px;
}

.eyebrow,
.section__eyebrow {
  margin: 0 0 1.1rem;
  color: var(--gold);
  font-size: var(--step--1);
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.hero__title {
  font-size: var(--step-4);
  max-width: 16ch;
  margin-inline: auto;
}

.lede {
  margin: clamp(1.3rem, 3vw, 1.9rem) auto 0;
  max-width: 60ch;
  color: var(--muted);
  font-size: var(--step-1);
  line-height: 1.55;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.9rem;
  margin-top: clamp(1.8rem, 4vw, 2.6rem);
}

.hero__signals {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.8rem clamp(1.2rem, 3vw, 2.4rem);
  margin-top: clamp(2.2rem, 5vw, 3.4rem);
  color: #dce5f1;
  font-size: var(--step--1);
}

.hero__signals li {
  display: inline-flex;
  align-items: center;
}

.hero__signals li::before {
  content: "";
  width: 0.42rem;
  height: 0.42rem;
  margin-right: 0.6rem;
  background: var(--steel);
  transform: rotate(45deg);
}

/* ---------- Sections ---------- */
.section {
  padding-block: var(--space-xl);
  border-top: 1px solid var(--line);
}

.section--alt {
  background: linear-gradient(180deg, var(--surface-alt), transparent);
}

.section__title {
  font-size: var(--step-3);
  max-width: 22ch;
}

.section__lede {
  margin-top: var(--space-md);
  max-width: 62ch;
  color: var(--muted);
  font-size: var(--step-1);
}

.section__note {
  margin-top: var(--space-md);
  color: var(--faint);
  font-size: var(--step--1);
  border-left: 2px solid var(--gold);
  padding-left: 1rem;
}

/* ---------- Grid + cards ---------- */
.grid {
  display: grid;
  gap: clamp(1rem, 2.2vw, 1.5rem);
  margin-top: var(--space-lg);
}

.grid--2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid--3 {
  grid-template-columns: repeat(3, 1fr);
}

.card {
  padding: clamp(1.4rem, 2.5vw, 1.9rem);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  transition: transform var(--transition), border-color var(--transition),
    background var(--transition);
}

.card:hover {
  transform: translateY(-3px);
  border-color: var(--line-strong);
  background: var(--surface-2);
}

.card__title {
  font-size: var(--step-1);
  margin-bottom: 0.6rem;
}

.card--principle .card__title {
  color: var(--ink);
}

.card--principle .card__title::before {
  content: "";
  display: inline-block;
  width: 0.5rem;
  height: 0.5rem;
  margin-right: 0.6rem;
  background: var(--gold);
  transform: rotate(45deg);
  vertical-align: middle;
}

.card__body {
  color: var(--muted);
  font-size: var(--step-0);
}

/* ---------- Steps ---------- */
.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: clamp(1rem, 2.2vw, 1.5rem);
  margin-top: var(--space-lg);
  counter-reset: step;
}

.step {
  position: relative;
  padding: clamp(1.4rem, 2.5vw, 1.9rem);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.step__index {
  display: block;
  margin-bottom: 0.9rem;
  font-size: var(--step-2);
  font-weight: 700;
  color: var(--steel);
  font-variant-numeric: tabular-nums;
}

.step__title {
  font-size: var(--step-1);
  margin-bottom: 0.5rem;
}

.step__body {
  color: var(--muted);
  font-size: var(--step-0);
}

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

.feature-list {
  display: grid;
  gap: 0.9rem;
}

.feature {
  padding: 1.1rem 1.25rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.feature__title {
  font-size: var(--step-0);
  font-weight: 600;
  margin-bottom: 0.3rem;
}

.feature__title::before {
  content: "";
  display: inline-block;
  width: 0.42rem;
  height: 0.42rem;
  margin-right: 0.6rem;
  background: var(--steel);
  transform: rotate(45deg);
  vertical-align: middle;
}

.feature__body {
  color: var(--muted);
  font-size: var(--step--1);
}

/* ---------- FAQ ---------- */
.faq {
  margin-top: var(--space-lg);
  border-top: 1px solid var(--line);
}

.faq__item {
  border-bottom: 1px solid var(--line);
}

.faq__question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.25rem 0;
  font-size: var(--step-1);
  font-weight: 550;
  cursor: pointer;
  list-style: none;
}

.faq__question::-webkit-details-marker {
  display: none;
}

.faq__question::after {
  content: "";
  flex: none;
  width: 0.62rem;
  height: 0.62rem;
  border-right: 2px solid var(--gold);
  border-bottom: 2px solid var(--gold);
  transform: rotate(45deg);
  transition: transform var(--transition);
}

.faq__item[open] .faq__question::after {
  transform: rotate(-135deg);
}

.faq__answer {
  padding-bottom: 1.4rem;
  max-width: 64ch;
  color: var(--muted);
}

/* ---------- CTA ---------- */
.cta {
  padding-block: var(--space-xl);
  border-top: 1px solid var(--line);
  background:
    radial-gradient(circle at 50% 0%, rgba(242, 203, 138, 0.1), transparent 22rem),
    var(--surface-alt);
  text-align: center;
}

.cta__inner {
  max-width: 640px;
}

.cta__title {
  font-size: var(--step-3);
}

.cta__body {
  margin: var(--space-md) auto 0;
  max-width: 52ch;
  color: var(--muted);
  font-size: var(--step-1);
}

.cta__actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.9rem;
  margin-top: var(--space-lg);
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--line);
  padding-block: clamp(2.5rem, 5vw, 4rem);
}

.site-footer__inner {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: var(--space-lg);
  align-items: start;
}

.site-footer__tagline {
  margin-top: 0.6rem;
  color: var(--faint);
  font-size: var(--step--1);
  max-width: 32ch;
}

.site-footer__nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem 1.4rem;
  justify-content: flex-end;
}

.site-footer__nav a {
  color: var(--muted);
  font-size: var(--step--1);
  transition: color var(--transition);
}

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

.site-footer__legal {
  grid-column: 1 / -1;
  padding-top: var(--space-md);
  border-top: 1px solid var(--line);
  color: var(--faint);
  font-size: var(--step--1);
}

/* ---------- Error page ---------- */
.error-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  text-align: center;
  padding: clamp(1.5rem, 6vw, 4rem);
}

.error-shell__inner {
  max-width: 540px;
}

.error-shell .brand {
  justify-content: center;
}

.error-shell__eyebrow {
  margin-top: 2rem;
}

.error-shell__title {
  font-size: var(--step-3);
}

.error-shell .button {
  margin-top: var(--space-lg);
}

/* =========================================================================
   Responsive
   ========================================================================= */
@media (max-width: 880px) {
  .grid--3,
  .steps {
    grid-template-columns: repeat(2, 1fr);
  }

  .split {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .nav-toggle {
    display: inline-flex;
  }

  .nav-menu {
    position: absolute;
    inset: var(--header-h) 0 auto;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 0.5rem clamp(1.15rem, 4vw, 2.5rem) 1.25rem;
    background: #060810;
    border-bottom: 1px solid var(--line);
    box-shadow: var(--shadow);
    transform: translateY(-8px);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition), transform var(--transition),
      visibility var(--transition);
  }

  .nav-toggle-input:checked ~ .nav-menu {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav-menu li {
    padding-block: 0.35rem;
    border-bottom: 1px solid var(--line);
  }

  .nav-menu li:last-child {
    border-bottom: 0;
  }

  .nav-menu a:not(.button) {
    display: block;
    padding-block: 0.55rem;
    font-size: var(--step-0);
  }

  .nav-menu__cta {
    margin-left: 0;
    margin-top: 0.6rem;
  }

  .nav-menu__cta .button {
    width: 100%;
  }
}

@media (max-width: 560px) {
  .grid--2,
  .grid--3,
  .steps {
    grid-template-columns: 1fr;
  }

  .site-footer__inner {
    grid-template-columns: 1fr;
  }

  .site-footer__nav {
    justify-content: flex-start;
  }
}

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

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}