/* ============================================================
   АРК Формат — корпоративный сайт
   Единая таблица стилей. Без зависимостей и сборки.
   ============================================================ */

:root {
  --c-bg: #ffffff;
  --c-bg-soft: #f6f8fb;
  --c-dark: #101216;
  --c-dark-2: #181b20;
  --c-text: #1a2233;
  --c-text-soft: #5a6478;
  --c-accent: #16181d;
  --c-accent-hover: #000000;
  --c-accent-soft: #f1f3f6;
  --c-border: #e3e8f0;
  --c-white: #ffffff;
  --radius: 14px;
  --radius-sm: 10px;
  --shadow: 0 10px 30px rgba(14, 21, 38, 0.08);
  --shadow-lg: 0 20px 60px rgba(14, 21, 38, 0.14);
  --font: "Inter", "Helvetica Neue", Arial, "Segoe UI", sans-serif;
  --container: 1160px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  color: var(--c-text);
  background: var(--c-bg);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

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

a { color: var(--c-accent); text-decoration: none; }
a:hover { color: var(--c-accent-hover); }

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Типографика ---------- */

h1, h2, h3, h4 { line-height: 1.25; font-weight: 700; letter-spacing: -0.01em; }

h1 { font-size: clamp(32px, 5vw, 54px); }
h2 { font-size: clamp(26px, 3.6vw, 38px); }
h3 { font-size: 20px; }

.section-title { margin-bottom: 16px; }

.section-sub {
  color: var(--c-text-soft);
  font-size: 18px;
  max-width: 720px;
  margin-bottom: 48px;
}

.eyebrow {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--c-accent);
  margin-bottom: 14px;
}

/* ---------- Кнопки ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  border-radius: 999px;
  font-size: 16px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-primary {
  background: var(--c-accent);
  color: var(--c-white);
}
.btn-primary:hover { background: var(--c-accent-hover); color: var(--c-white); transform: translateY(-1px); }

.btn-ghost {
  background: transparent;
  color: var(--c-white);
  border: 1px solid rgba(255, 255, 255, 0.35);
}
.btn-ghost:hover { border-color: var(--c-white); color: var(--c-white); }

.btn-outline {
  background: transparent;
  color: var(--c-text);
  border: 1px solid var(--c-border);
}
.btn-outline:hover { border-color: var(--c-accent); color: var(--c-accent); }

/* ---------- Шапка ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--c-border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.logo {
  display: flex;
  align-items: center;
  color: var(--c-text);
  font-weight: 700;
}

.logo:hover { color: var(--c-text); }

.logo-img {
  display: block;
  height: 40px;
  width: auto;
}

.logo-img-footer { height: 44px; }

.main-nav ul {
  display: flex;
  gap: 30px;
  list-style: none;
}

.main-nav a {
  color: var(--c-text);
  font-weight: 500;
  font-size: 15px;
  padding: 6px 0;
  border-bottom: 2px solid transparent;
  transition: border-color 0.2s;
}

.main-nav a:hover,
.main-nav a.active { color: var(--c-accent); border-bottom-color: var(--c-accent); }

.header-cta { display: flex; align-items: center; gap: 16px; }
.header-cta .btn { padding: 10px 22px; font-size: 15px; }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}
.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--c-text);
  margin: 5px 0;
  border-radius: 2px;
  transition: 0.25s;
}

/* ---------- Hero ---------- */

.hero {
  background:
    radial-gradient(1200px 500px at 80% -10%, rgba(160, 170, 185, 0.14), transparent 60%),
    radial-gradient(900px 500px at 10% 110%, rgba(160, 170, 185, 0.09), transparent 55%),
    var(--c-dark);
  color: var(--c-white);
  padding: 110px 0 130px;
}

.hero-inner { max-width: 860px; }

.hero .eyebrow { color: #b9c1cc; }

.hero h1 { margin-bottom: 24px; }

.hero .lead {
  font-size: 20px;
  color: rgba(255, 255, 255, 0.78);
  max-width: 700px;
  margin-bottom: 40px;
}

.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }

.hero-note {
  margin-top: 28px;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.55);
}

/* ---------- Полоса цифр ---------- */

.stats-strip {
  background: var(--c-dark-2);
  color: var(--c-white);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  padding: 40px 0;
}

.stat b {
  display: block;
  font-size: 34px;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.stat span {
  font-size: 14px;
  color: rgba(255, 255, 255, 0.65);
}

/* ---------- Секции ---------- */

.section { padding: 96px 0; }
.section-soft { background: var(--c-bg-soft); }
.section-dark {
  background: var(--c-dark);
  color: var(--c-white);
}
.section-dark .section-sub { color: rgba(255, 255, 255, 0.7); }

/* ---------- «Мы подходим, если» ---------- */

.fit-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.fit-card {
  background: var(--c-white);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
}

.fit-card .fit-icon { font-size: 28px; margin-bottom: 16px; }

.fit-card h3 { margin-bottom: 10px; font-size: 18px; }

.fit-card p { color: var(--c-text-soft); font-size: 15px; }

/* ---------- Услуги ---------- */

.services-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.service-card {
  background: var(--c-white);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 30px;
  display: flex;
  flex-direction: column;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.service-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.service-num {
  font-size: 13px;
  font-weight: 700;
  color: var(--c-accent);
  margin-bottom: 18px;
  letter-spacing: 0.08em;
}

.service-card h3 { margin-bottom: 12px; }

.service-card p { color: var(--c-text-soft); font-size: 15px; margin-bottom: 18px; }

.service-list {
  list-style: none;
  margin-top: auto;
}

.service-list li {
  position: relative;
  padding-left: 22px;
  margin-bottom: 8px;
  font-size: 14px;
  color: var(--c-text-soft);
}

.service-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 9px;
  width: 10px;
  height: 10px;
  border-radius: 3px;
  background: var(--c-accent-soft);
  border: 2px solid var(--c-accent);
  box-sizing: border-box;
}

/* ---------- Процесс ---------- */

.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.step-card {
  background: var(--c-bg-soft);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 28px;
}

.step-card p { color: var(--c-text-soft); font-size: 15px; }

/* Вариант карточки на тёмном фоне */

.section-dark .step-card {
  background: rgba(255, 255, 255, 0.04);
  border-color: rgba(255, 255, 255, 0.1);
}

.section-dark .step-card p { color: rgba(255, 255, 255, 0.7); }

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border-radius: 12px;
  background: var(--c-accent);
  color: var(--c-white);
  font-weight: 800;
  font-size: 18px;
  margin-bottom: 18px;
}

.step-card h3 { margin-bottom: 10px; font-size: 18px; }

/* Тёмные секции: бейдж-цифра почти чёрная — нужен контур */
.section-dark .step-num {
  border: 1px solid rgba(255, 255, 255, 0.4);
}

/* ---------- Принципы ---------- */

.principles-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.principle-card {
  background: var(--c-white);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 30px;
}

.principle-card h3 { margin-bottom: 10px; font-size: 18px; }
.principle-card p { color: var(--c-text-soft); font-size: 15px; }

/* ---------- Кейсы ---------- */

.cases-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.case-card {
  background: var(--c-white);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 32px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.case-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }

.case-tag {
  display: inline-block;
  align-self: flex-start;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--c-accent);
  background: var(--c-accent-soft);
  border-radius: 999px;
  padding: 6px 14px;
}

.case-card h3 { font-size: 20px; }
.case-card > p { color: var(--c-text-soft); font-size: 15px; }

.case-result {
  margin-top: auto;
  padding-top: 16px;
  border-top: 1px dashed var(--c-border);
  font-size: 14px;
}

.case-result b { color: var(--c-text); }

/* ---------- Команда ---------- */

.team-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.team-card {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius);
  padding: 28px;
}

.team-role { font-weight: 700; margin-bottom: 8px; font-size: 17px; }
.team-card p { color: rgba(255, 255, 255, 0.7); font-size: 15px; }

/* ---------- Технологии ---------- */

.stack-groups { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }

.stack-group {
  background: var(--c-white);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 26px;
}

.stack-group h3 { font-size: 16px; margin-bottom: 16px; }

.stack-tags { display: flex; flex-wrap: wrap; gap: 8px; }

.tag {
  font-size: 13px;
  font-weight: 500;
  background: var(--c-bg-soft);
  border: 1px solid var(--c-border);
  color: var(--c-text);
  border-radius: 999px;
  padding: 6px 14px;
}

/* ---------- Модели сотрудничества ---------- */

.models-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.model-card {
  background: var(--c-white);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 30px;
}

.model-card .model-name {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 12px;
}

.model-card p { color: var(--c-text-soft); font-size: 15px; margin-bottom: 14px; }

.model-card ul { list-style: none; }

.model-card li {
  position: relative;
  padding-left: 20px;
  font-size: 14px;
  color: var(--c-text-soft);
  margin-bottom: 6px;
}

.model-card li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--c-accent);
  font-weight: 700;
}

/* ---------- FAQ ---------- */

.faq-item {
  background: var(--c-white);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  margin-bottom: 12px;
  overflow: hidden;
}

.faq-item summary {
  cursor: pointer;
  padding: 20px 24px;
  font-weight: 600;
  font-size: 16px;
  list-style: none;
  position: relative;
  padding-right: 56px;
}

.faq-item summary::-webkit-details-marker { display: none; }

.faq-item summary::after {
  content: "+";
  position: absolute;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 24px;
  font-weight: 400;
  color: var(--c-accent);
  transition: transform 0.2s;
}

.faq-item[open] summary::after { transform: translateY(-50%) rotate(45deg); }

.faq-item .faq-body {
  padding: 0 24px 20px;
  color: var(--c-text-soft);
  font-size: 15px;
}

/* ---------- CTA-блок ---------- */

.cta-box {
  background:
    radial-gradient(700px 300px at 90% 0%, rgba(160, 170, 185, 0.16), transparent 60%),
    var(--c-dark);
  border-radius: 24px;
  color: var(--c-white);
  padding: 72px 64px;
  text-align: center;
}

.cta-box h2 { margin-bottom: 16px; }

.cta-box p {
  color: rgba(255, 255, 255, 0.75);
  max-width: 560px;
  margin: 0 auto 36px;
  font-size: 17px;
}

.cta-actions { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

/* ---------- Контакты ---------- */

.contact-layout {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 48px;
  align-items: start;
}

.contact-list { list-style: none; }

.contact-list li { margin-bottom: 22px; }

.contact-list .label {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--c-text-soft);
  margin-bottom: 4px;
}

.contact-list .value { font-size: 17px; font-weight: 600; }

.contact-form {
  background: var(--c-white);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 36px;
  box-shadow: var(--shadow);
}

.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }

.form-group { margin-bottom: 18px; }

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 13px 16px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 15px;
  color: var(--c-text);
  background: var(--c-bg);
  transition: border-color 0.2s;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--c-accent);
}

.form-group textarea { resize: vertical; min-height: 120px; }

.form-note {
  font-size: 13px;
  color: var(--c-text-soft);
  margin-top: 12px;
}

.form-status {
  margin-top: 14px;
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  background: var(--c-accent-soft);
  border: 1px solid #d9dfe7;
  font-size: 14px;
}

/* ---------- Футер ---------- */

.site-footer {
  background: var(--c-dark);
  color: rgba(255, 255, 255, 0.7);
  padding: 64px 0 32px;
  font-size: 14px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 48px;
}

.footer-brand p {
  margin-top: 16px;
  max-width: 300px;
  color: rgba(255, 255, 255, 0.55);
}

.footer-col h4 {
  color: var(--c-white);
  font-size: 15px;
  margin-bottom: 18px;
}

.footer-col ul { list-style: none; }

.footer-col li { margin-bottom: 10px; }

.footer-col a { color: rgba(255, 255, 255, 0.65); }

.footer-col a:hover { color: var(--c-white); }

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 28px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  color: rgba(255, 255, 255, 0.45);
}

/* ---------- Анимации появления ---------- */
/* Применяются только когда JS работает (html.has-js);
   без JS весь контент виден сразу. */

.has-js .reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.has-js .reveal.visible {
  opacity: 1;
  transform: none;
}

/* ---------- Адаптив ---------- */

@media (max-width: 960px) {
  .fit-grid, .services-grid, .steps-grid, .models-grid, .team-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .cases-grid, .principles-grid, .stack-groups { grid-template-columns: 1fr; }
  .contact-layout { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
  .fit-grid, .services-grid, .steps-grid, .models-grid, .team-grid {
    grid-template-columns: 1fr;
  }
  .section { padding: 64px 0; }
  .hero { padding: 72px 0 88px; }
  .cta-box { padding: 48px 28px; }
  .form-row { grid-template-columns: 1fr; }

  .main-nav {
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    background: var(--c-white);
    border-bottom: 1px solid var(--c-border);
    display: none;
    padding: 16px 24px 24px;
  }
  .main-nav.open { display: block; }
  .main-nav ul { flex-direction: column; gap: 4px; }
  .main-nav a { display: block; padding: 12px 0; border-bottom: none; font-size: 17px; }

  .nav-toggle { display: block; }
  .header-cta .btn { display: none; }
}