/* =========================================================================
   Victor Karalkin — AI systems integration
   Static landing page. No build step, no external requests, no fonts to fetch.
   Values mirror landing-source-spec.py: content width 1080 on a 1440 page.
   ========================================================================= */

:root {
  --ink:    #14263B;
  --ink2:   #1C3247;
  --ink3:   #0E1C2B;  /* footer */
  --accent: #C2691C;
  --accent-hover: #A8570F;
  --slate:  #5B6B7C;
  --paper:  #FAF8F5;
  --white:  #FFFFFF;
  --graybx: #EFEDE8;
  --ambbx:  #FBF2E6;
  --line:   #DFDBD3;
  --muted:  #8A98A6;
  --light:  #C7D2DC;
  --hairline-dark: #24384B;
  --ghost-border:  #4A6076;

  --wrap: 1080px;
  --pad: 24px;
  --nav-h: 88px;

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial,
          "Helvetica Neue", sans-serif;
}

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

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background: var(--white);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; }

h1, h2, h3 { margin: 0; font-weight: 700; letter-spacing: -0.01em; }

p { margin: 0; }

b, strong { font-weight: 700; }

/* Content column is exactly --wrap wide; padding sits outside it, so the
   desktop layout matches the 1080-in-1440 preview to the pixel. */
.wrap {
  width: 100%;
  max-width: calc(var(--wrap) + var(--pad) * 2);
  margin: 0 auto;
  padding: 0 var(--pad);
}

.accent { color: var(--accent); }

/* Anchor targets clear the sticky nav */
[id] { scroll-margin-top: calc(var(--nav-h) + 16px); }

/* ---------------------------------------------------------------- shared */

.kicker {
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 14px;
}
.kicker--sm { font-size: 11px; margin-bottom: 12px; }

section > .wrap > h2 {
  font-size: clamp(26px, 3.4vw, 34px);
  line-height: 1.2;
  margin-bottom: 30px;
}

/* ---------------------------------------------------------------- buttons */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  text-decoration: none;
  font-weight: 700;
  border-radius: 7px;
  transition: background-color .15s ease, border-color .15s ease, color .15s ease;
}
.btn:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }

.btn--accent { background: var(--accent); color: var(--white); }
.btn--accent:hover { background: var(--accent-hover); }

.btn--ghost {
  border: 1.4px solid var(--ghost-border);
  color: var(--light);
  font-weight: 400;
}
.btn--ghost:hover { border-color: var(--light); color: var(--white); }

.btn--sm { height: 40px; padding: 0 22px; font-size: 14px; border-radius: 6px; }
.btn--lg { min-height: 56px; padding: 12px 28px; font-size: 16px; }
.btn--xl { min-height: 58px; padding: 12px 40px; font-size: 17px; }

/* ---------------------------------------------------------------- nav */

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--white);
  border-bottom: 1px solid var(--line);
}

.nav__inner {
  height: var(--nav-h);
  display: flex;
  align-items: center;
  gap: 20px;
}

.nav__brand {
  display: flex;
  align-items: baseline;
  gap: 14px;
  text-decoration: none;
  margin-right: auto;
}
.nav__name { font-size: 19px; font-weight: 700; color: var(--ink); }
.nav__tagline { font-size: 13px; color: var(--muted); }

.nav__links { display: flex; gap: 28px; }
.nav__links a {
  font-size: 14px;
  color: var(--slate);
  text-decoration: none;
  transition: color .15s ease;
}
.nav__links a:hover { color: var(--ink); }

/* ---------------------------------------------------------------- hero */

.hero {
  background: var(--ink);
  color: var(--white);
  border-top: 6px solid var(--accent);
  padding: 100px 0 84px;
}

.hero__h1 {
  font-size: clamp(32px, 4.4vw, 52px);
  line-height: 1.21;
  max-width: 900px;
}

.hero__sub {
  margin-top: 28px;
  max-width: 760px;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.56;
  color: var(--light);
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 22px;
  margin-top: 40px;
}
.hero__actions .btn--accent { min-width: 420px; }
.hero__actions .btn--ghost { min-width: 200px; }

.hero__note {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 48px;
  margin-top: 36px;
  font-size: 13px;
  color: var(--muted);
}

/* ---------------------------------------------------------------- problem */

.problem { background: var(--paper); padding: 74px 0; }
.problem__text {
  max-width: 960px;
  margin: 0 auto;
  text-align: center;
  font-size: clamp(19px, 2.2vw, 25px);
  line-height: 1.52;
}

/* ---------------------------------------------------------------- demo */

.demo { background: var(--white); padding: 76px 0; }

.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 34px;
}
.tab {
  appearance: none;
  border: 0;
  cursor: pointer;
  font-family: inherit;
  font-size: 14px;
  font-weight: 700;
  height: 40px;
  padding: 0 22px;
  border-radius: 20px;
  background: var(--graybx);
  color: var(--slate);
  transition: background-color .15s ease, color .15s ease;
}
.tab:hover { background: #E4E1DA; }
.tab.is-active { background: var(--ink); color: var(--white); }
.tab:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

.panel[hidden] { display: none; }

.panel__q {
  font-size: clamp(18px, 2vw, 22px);
  font-weight: 700;
  font-style: italic;
  line-height: 1.35;
  margin-bottom: 26px;
}

.answers {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 34px;
}

.answer { padding: 26px 28px; }
.answer--before { background: var(--graybx); }
.answer--after  { background: var(--ambbx); border-left: 4px solid var(--accent); }

.answer__label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  margin-bottom: 12px;
}
.answer--before .answer__label { color: var(--slate); }
.answer--after  .answer__label { color: var(--accent); }

.answer__body { font-size: 15px; line-height: 1.53; }
.answer--before .answer__body { color: var(--slate); }
.answer--after  .answer__body { color: var(--ink); }

.panel__caption {
  margin-top: 28px;
  font-size: 15px;
  font-style: italic;
  color: var(--slate);
}

.panel .kicker--sm { margin-top: 30px; }

.value {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}
.value li {
  position: relative;
  padding-left: 20px;
  font-size: 15px;
  line-height: 1.4;
}
.value li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 7px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
}

/* ---------------------------------------------------------------- security */

.security { background: var(--paper); padding: 76px 0; }

.cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.card { background: var(--graybx); padding: 24px 18px; }
/* left padding trimmed by the width of the rule, so labels get the same
   text column as the plain cards and stay on one line */
.card--accent { background: var(--ambbx); border-left: 4px solid var(--accent); padding-left: 14px; }

.card__label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.015em;
  text-transform: uppercase;
  color: var(--slate);
  margin-bottom: 12px;
}
.card--accent .card__label { color: var(--accent); }

.card__body { font-size: 14px; line-height: 1.5; }

.bus {
  margin-top: 34px;
  background: var(--ink);
  border-left: 4px solid var(--accent);
  padding: 26px 28px;
}
.bus__label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 14px;
}
.bus__body { font-size: 14.5px; line-height: 1.52; color: var(--light); }
.bus__body b { color: var(--white); }

/* ---------------------------------------------------------------- scope */

.scope { background: var(--white); padding: 76px 0; }

.scope__cols {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
}
.scope__col h3 { font-size: 19px; margin-bottom: 24px; }

.list { list-style: none; margin: 0; padding: 0; }
.list li {
  position: relative;
  padding-left: 26px;
  font-size: 15px;
  line-height: 1.4;
  margin-bottom: 16px;
}
.list--do li { color: var(--ink); }
.list--do li::before { content: "\2192"; position: absolute; left: 0; color: var(--accent); font-weight: 700; }
.list--dont li { color: var(--slate); }
.list--dont li b { color: var(--slate); }
.list--dont li::before { content: "\2014"; position: absolute; left: 0; color: var(--slate); font-weight: 700; }

.plumber {
  margin-top: 30px;
  background: var(--ambbx);
  border-left: 4px solid var(--accent);
  padding: 24px;
}
.plumber .card__label { color: var(--accent); }
.plumber .card__body { font-size: 15px; line-height: 1.47; }

/* ---------------------------------------------------------------- principles */

.principles { background: var(--paper); padding: 76px 0; }

.principles__intro {
  max-width: 960px;
  font-size: clamp(16px, 1.7vw, 18px);
  line-height: 1.56;
  margin-bottom: 38px;
}

.principle {
  border-left: 4px solid var(--accent);
  padding-left: 26px;
  margin-bottom: 34px;
  max-width: 990px;
}
.principle h3 { font-size: 19px; line-height: 1.3; margin-bottom: 12px; }
.principle p { font-size: 15px; line-height: 1.47; color: var(--slate); }

.bio {
  background: var(--graybx);
  padding: 24px 26px;
  font-size: 14.5px;
  line-height: 1.45;
  color: var(--slate);
}
.bio a { color: var(--slate); }
.bio a:hover { color: var(--accent); }

/* ---------------------------------------------------------------- steps */

.steps { background: var(--white); padding: 76px 0; }

.steps__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.step {
  background: var(--ink);
  border-top: 5px solid var(--accent);
  padding: 26px 24px 30px;
  color: var(--white);
}
.step__num { font-size: 30px; font-weight: 700; color: var(--accent); line-height: 1; margin-bottom: 22px; }
.step__head { font-size: 16px; font-weight: 700; line-height: 1.3; margin-bottom: 12px; }
.step__body { font-size: 13.5px; line-height: 1.4; color: var(--light); }

/* ---------------------------------------------------------------- cta */

.cta {
  background: var(--ink);
  color: var(--white);
  text-align: center;
  padding: 88px 0 96px;
}
.cta__h2 {
  font-size: clamp(26px, 3.8vw, 38px);
  line-height: 1.21;
}
.cta__sub {
  max-width: 720px;
  margin: 22px auto 34px;
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.53;
  color: var(--light);
}

/* ---------------------------------------------------------------- footer */

.footer { background: var(--ink3); color: var(--white); padding: 62px 0 60px; }

.footer__top {
  display: flex;
  flex-wrap: wrap;
  gap: 30px;
  justify-content: space-between;
  align-items: flex-start;
}
.footer__name { font-size: 20px; font-weight: 700; }
.footer__meta { margin-top: 10px; font-size: 15px; color: var(--muted); }

.footer__contacts {
  list-style: none;
  margin: 0;
  padding: 0;
  text-align: right;
  font-size: 15px;
  color: var(--light);
}
.footer__contacts li + li { margin-top: 8px; }
.footer__contacts a { text-decoration: none; transition: color .15s ease; }
.footer__contacts a:hover { color: var(--accent); }

.footer__tech {
  margin-top: 32px;
  padding-top: 30px;
  border-top: 1px solid var(--hairline-dark);
  max-width: 780px;
  font-size: 13px;
  line-height: 1.46;
  color: var(--muted);
}
.footer__tech b { color: var(--light); }

/* ---------------------------------------------------------------- 404 */
/* Lives here rather than in a <style> block so the CSP can stay style-src 'self'. */

.notfound {
  background: var(--ink);
  color: var(--white);
  min-height: 100vh;
  display: flex;
  align-items: center;
  border-top: 6px solid var(--accent);
}
.notfound h1 { font-size: clamp(30px, 4vw, 46px); line-height: 1.2; }
.notfound p {
  margin-top: 20px;
  max-width: 560px;
  font-size: 17px;
  line-height: 1.56;
  color: var(--light);
}
.notfound .btn { margin-top: 34px; }

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

@media (max-width: 980px) {
  .cards         { grid-template-columns: repeat(2, 1fr); }
  .steps__grid   { grid-template-columns: repeat(2, 1fr); }
  .scope__cols   { grid-template-columns: 1fr; gap: 44px; }
  .value         { grid-template-columns: repeat(3, 1fr); gap: 22px; }
  .hero          { padding: 76px 0 68px; }
}

@media (max-width: 760px) {
  :root { --nav-h: 72px; --pad: 20px; }

  .nav__links { display: none; }
  .nav__brand { flex-direction: column; align-items: flex-start; gap: 2px; }
  .nav__name { font-size: 17px; }

  .hero { padding: 56px 0 52px; }
  .hero__actions { flex-direction: column; gap: 14px; align-items: stretch; }
  .hero__actions .btn { min-width: 0; width: 100%; }
  .hero__note { flex-direction: column; gap: 6px; }

  .problem { padding: 56px 0; }
  .problem__text { text-align: left; }

  .demo, .security, .scope, .principles, .steps { padding: 56px 0; }

  .answers       { grid-template-columns: 1fr; gap: 18px; }
  .value         { grid-template-columns: 1fr; gap: 14px; }
  .cards         { grid-template-columns: 1fr; }
  .steps__grid   { grid-template-columns: 1fr; }

  .principle { padding-left: 20px; margin-bottom: 28px; }

  .cta { padding: 64px 0 68px; }

  .footer { padding: 48px 0; }
  .footer__contacts { text-align: left; }
}

@media (max-width: 420px) {
  .tabs { gap: 10px; }
  .tab { padding: 0 16px; font-size: 13px; }
  .btn--sm { padding: 0 16px; font-size: 13px; }
}