/**
 * v2 — Knowledge hub page: /knowledge (главная Базы знаний).
 *
 * Использует общие переменные --xh-* из home.css. Namespace: xk-hub-*.
 * Заменяет старый kb-hub.css (kb-* префикс) для единого xk-* слоя.
 *
 * Адаптация макета knowledge-base.html. 5 секций: hero/sections/popular/dual/trust/help.
 *
 * @since 2026-05-25
 */

/* ================= HERO ================= */
.xk-hub-hero {
  position: relative;
  z-index: 1;
  padding: 48px 0 56px;
  overflow: hidden;
}
.xk-hub-hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}
.xk-hub-hero-bg picture,
.xk-hub-hero-bg img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: .35;
}
.xk-hub-hero-bg::after {
  content: '';
  position: absolute;
  inset: 0;
  background:
    linear-gradient(135deg, rgba(6,10,20,.78) 0%, rgba(6,10,20,.65) 40%, rgba(6,10,20,.50) 70%),
    linear-gradient(180deg, transparent 50%, var(--xh-bg-deep) 100%);
}
.xk-hub-hero-inner {
  position: relative;
  z-index: 1;
  max-width: var(--xh-max-w);
  margin: 0 auto;
  padding: 0 var(--xh-container-pad);
  display: grid;
  grid-template-columns: 1fr 400px;
  gap: 48px;
  align-items: center;
}
.xk-hub-hero-left { max-width: 600px; }
.xk-hub-hero-inner .xh-breadcrumbs { margin-bottom: 14px; }

.xk-hub-hero-title {
  font-family: var(--xh-font-display);
  font-size: clamp(30px, 4vw, 46px);
  text-transform: uppercase;
  letter-spacing: 1px;
  color: #fff;
  line-height: 1.05;
  margin: 0 0 10px;
}
.xk-hub-hero-subtitle {
  font-family: var(--xh-font-heading);
  font-size: 17px;
  font-weight: 700;
  color: var(--xh-text);
  letter-spacing: .3px;
  margin: 0 0 8px;
}
.xk-hub-hero-desc {
  font-size: 15px;
  color: var(--xh-text-secondary);
  line-height: 1.6;
  margin: 0 0 28px;
  max-width: 480px;
}

/* Search bar */
.xk-hub-search {
  display: flex;
  align-items: center;
  gap: 0;
  background: rgba(12,19,34,.85);
  border: 1px solid var(--xh-border-light);
  border-radius: var(--xh-radius-lg);
  overflow: hidden;
  transition: border-color var(--xh-transition);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  max-width: 520px;
}
.xk-hub-search:focus-within {
  border-color: var(--xh-blue);
  box-shadow: 0 0 0 3px rgba(42,125,225,.18);
}
.xk-hub-search-icon {
  padding: 0 18px;
  color: var(--xh-text-muted);
  display: flex;
  align-items: center;
}
.xk-hub-search-icon svg { width: 20px; height: 20px; }
.xk-hub-search input {
  flex: 1;
  background: none;
  border: none;
  outline: none;
  font-family: var(--xh-font-body);
  font-size: 16px;
  color: var(--xh-text);
  padding: 16px 0;
  min-width: 0;
}
.xk-hub-search input::placeholder { color: var(--xh-text-muted); }
.xk-hub-search-btn {
  padding: 16px 22px;
  background: none;
  border: none;
  border-left: 1px solid var(--xh-border);
  color: var(--xh-blue-light);
  cursor: pointer;
  display: flex;
  align-items: center;
  transition: background var(--xh-transition);
}
.xk-hub-search-btn:hover { background: rgba(42,125,225,.08); }
.xk-hub-search-btn svg { width: 20px; height: 20px; }

/* Fact chips */
.xk-hub-facts {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 24px;
}
.xk-hub-fact {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: var(--xh-radius);
  border: 1px solid var(--xh-border);
  background: rgba(12,19,34,.6);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  font-family: var(--xh-font-heading);
  font-weight: 600;
}
.xk-hub-fact-val { font-size: 18px; color: #fff; line-height: 1; }
.xk-hub-fact-label { font-size: 12px; color: var(--xh-text-muted); line-height: 1.2; }

/* Hero art (illustrative box) */
.xk-hub-hero-art {
  position: relative;
  border-radius: var(--xh-radius-lg);
  overflow: hidden;
  aspect-ratio: 4/3;
  border: 1px solid var(--xh-border-light);
  background: linear-gradient(135deg, #0a1428 0%, #14233f 50%, #1a2848 100%);
  display: flex;
  align-items: center;
  justify-content: center;
}
.xk-hub-hero-art::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 60% 40%, rgba(232,132,30,.08) 0%, transparent 60%);
  pointer-events: none;
}
.xk-hub-hero-art img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ================= SECTIONS (5 разделов) ================= */
.xk-hub-sections {
  position: relative;
  z-index: 1;
  padding: 56px 0;
}
.xk-hub-sections-inner {
  max-width: var(--xh-max-w);
  margin: 0 auto;
  padding: 0 var(--xh-container-pad);
}
.xk-hub-sec-title {
  font-family: var(--xh-font-heading);
  font-size: 24px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: #fff;
  margin: 0 0 28px;
  text-align: center;
}
.xk-hub-sec-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
}
.xk-hub-sec-card {
  background: var(--xh-bg-card);
  border: 1px solid var(--xh-border);
  border-radius: var(--xh-radius-lg);
  padding: 24px 20px;
  transition: border-color var(--xh-transition), transform var(--xh-transition), box-shadow var(--xh-transition);
  display: flex;
  flex-direction: column;
  position: relative;
  overflow: hidden;
}
.xk-hub-sec-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  border-radius: var(--xh-radius-lg) var(--xh-radius-lg) 0 0;
}
.xk-hub-sec-card:hover {
  border-color: var(--xh-border-light);
  transform: translateY(-4px);
  box-shadow: 0 10px 32px rgba(0,0,0,.35);
}
/* Color accents (3px top stripe + icon background) */
.xk-hub-sec-card--enc::before   { background: var(--xh-teal); }
.xk-hub-sec-card--guide::before { background: var(--xh-orange); }
.xk-hub-sec-card--top::before   { background: var(--xh-purple); }
.xk-hub-sec-card--mech::before  { background: var(--xh-blue); }
.xk-hub-sec-card--dict::before  { background: var(--xh-yellow); }

.xk-hub-sec-icon {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 14px;
  flex-shrink: 0;
}
.xk-hub-sec-icon svg { width: 20px; height: 20px; }
.xk-hub-sec-icon--enc   { background: rgba(32,176,184,.10); border: 1px solid rgba(32,176,184,.28); color: var(--xh-teal); }
.xk-hub-sec-icon--guide { background: rgba(232,132,30,.10); border: 1px solid rgba(232,132,30,.28); color: var(--xh-orange); }
.xk-hub-sec-icon--top   { background: rgba(106,64,184,.10); border: 1px solid rgba(106,64,184,.28); color: var(--xh-purple); }
.xk-hub-sec-icon--mech  { background: rgba(42,125,225,.10); border: 1px solid rgba(42,125,225,.28); color: var(--xh-blue-light); }
.xk-hub-sec-icon--dict  { background: rgba(200,168,32,.10); border: 1px solid rgba(200,168,32,.28); color: var(--xh-yellow); }

.xk-hub-sec-card h3 {
  font-size: 15px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .4px;
  color: #fff;
  margin: 0 0 8px;
}
.xk-hub-sec-card p {
  font-size: 13px;
  color: var(--xh-text-secondary);
  line-height: 1.5;
  margin: 0 0 14px;
  flex: 1;
}
.xk-hub-sec-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-top: auto;
}
.xk-hub-sec-count {
  font-family: var(--xh-font-heading);
  font-size: 12px;
  font-weight: 600;
  color: var(--xh-text-muted);
  letter-spacing: .2px;
}
.xk-hub-sec-link {
  font-family: var(--xh-font-heading);
  font-size: 13px;
  font-weight: 700;
  color: var(--xh-orange);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  transition: color var(--xh-transition);
}
.xk-hub-sec-link svg { width: 14px; height: 14px; }
.xk-hub-sec-card:hover .xk-hub-sec-link { color: var(--xh-orange-hover); }

/* ================= POPULAR ================= */
.xk-hub-popular {
  position: relative;
  z-index: 1;
  padding: 56px 0;
  border-top: 1px solid var(--xh-border);
}
.xk-hub-popular-inner {
  max-width: var(--xh-max-w);
  margin: 0 auto;
  padding: 0 var(--xh-container-pad);
}
.xk-hub-pop-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
}
.xk-hub-pop-card {
  background: var(--xh-bg-card);
  border: 1px solid var(--xh-border);
  border-radius: var(--xh-radius-lg);
  overflow: hidden;
  transition: border-color var(--xh-transition), transform var(--xh-transition), box-shadow var(--xh-transition);
  display: flex;
  flex-direction: column;
}
.xk-hub-pop-card:hover {
  border-color: var(--xh-border-light);
  transform: translateY(-3px);
  box-shadow: 0 8px 28px rgba(0,0,0,.3);
}
.xk-hub-pop-img {
  width: 100%;
  aspect-ratio: 16/10;
  background: var(--xh-bg-placeholder-grad);
  border-bottom: 1px solid var(--xh-border);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}
.xk-hub-pop-img svg {
  width: 28px;
  height: 28px;
  color: var(--xh-text-muted);
  opacity: .25;
}
.xk-hub-pop-tag {
  position: absolute;
  top: 8px;
  left: 8px;
  font-family: var(--xh-font-heading);
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .5px;
  padding: 3px 10px;
  border-radius: 999px;
}
.xk-hub-pop-tag--guide { background: rgba(232,132,30,.18); border: 1px solid rgba(232,132,30,.3); color: var(--xh-orange); }
.xk-hub-pop-tag--top   { background: rgba(106,64,184,.18); border: 1px solid rgba(106,64,184,.3); color: var(--xh-purple); }
.xk-hub-pop-tag--mech  { background: rgba(42,125,225,.18); border: 1px solid rgba(42,125,225,.3); color: var(--xh-blue-light); }
.xk-hub-pop-tag--enc   { background: rgba(32,176,184,.18); border: 1px solid rgba(32,176,184,.3); color: var(--xh-teal); }

.xk-hub-pop-body {
  padding: 14px;
  flex: 1;
  display: flex;
  flex-direction: column;
}
.xk-hub-pop-title {
  font-family: var(--xh-font-heading);
  font-size: 14px;
  font-weight: 700;
  color: var(--xh-text);
  margin: 0 0 6px;
  line-height: 1.3;
  flex: 1;
}
.xk-hub-pop-desc {
  font-size: 12px;
  color: var(--xh-text-muted);
  line-height: 1.45;
  margin: 0 0 10px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.xk-hub-pop-action {
  font-family: var(--xh-font-heading);
  font-size: 12px;
  font-weight: 700;
  color: var(--xh-orange);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-top: auto;
}
.xk-hub-pop-action svg { width: 12px; height: 12px; }

/* ================= NEW + QUICK LINKS ================= */
.xk-hub-dual {
  position: relative;
  z-index: 1;
  padding: 56px 0;
  border-top: 1px solid var(--xh-border);
}
.xk-hub-dual-inner {
  max-width: var(--xh-max-w);
  margin: 0 auto;
  padding: 0 var(--xh-container-pad);
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}
.xk-hub-panel {
  background: var(--xh-bg-card);
  border: 1px solid var(--xh-border);
  border-radius: var(--xh-radius-lg);
  padding: 28px;
}
.xk-hub-panel-title {
  font-family: var(--xh-font-heading);
  font-size: 17px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: #fff;
  margin: 0 0 20px;
}

/* New articles list */
.xk-hub-new-list { display: flex; flex-direction: column; gap: 0; }
.xk-hub-new-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 13px 0;
  border-bottom: 1px solid var(--xh-border);
  transition: background var(--xh-transition);
}
.xk-hub-new-item:last-child { border-bottom: none; }
.xk-hub-new-item:hover {
  background: rgba(255,255,255,.02);
  margin: 0 -12px;
  padding-left: 12px;
  padding-right: 12px;
  border-radius: var(--xh-radius);
}
.xk-hub-new-icon {
  width: 38px;
  height: 38px;
  border-radius: var(--xh-radius);
  background: rgba(42,125,225,.08);
  border: 1px solid rgba(42,125,225,.22);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.xk-hub-new-icon svg { width: 16px; height: 16px; color: var(--xh-blue-light); }
.xk-hub-new-body { flex: 1; min-width: 0; }
.xk-hub-new-title-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 2px;
}
.xk-hub-new-name {
  font-family: var(--xh-font-heading);
  font-size: 14px;
  font-weight: 600;
  color: var(--xh-text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.xk-hub-new-badge {
  font-family: var(--xh-font-heading);
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .5px;
  padding: 2px 8px;
  border-radius: 999px;
  flex-shrink: 0;
  background: rgba(32,168,104,.15);
  border: 1px solid rgba(32,168,104,.3);
  color: var(--xh-green);
}
.xk-hub-new-meta {
  display: flex;
  gap: 12px;
  font-size: 12px;
  color: var(--xh-text-muted);
}
.xk-hub-new-section {
  color: var(--xh-blue-light);
  font-weight: 600;
  font-family: var(--xh-font-heading);
}

/* Quick links */
.xk-hub-quick-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}
.xk-hub-quick-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 11px 14px;
  border-radius: var(--xh-radius);
  border: 1px solid var(--xh-border);
  font-family: var(--xh-font-heading);
  font-size: 13px;
  font-weight: 600;
  color: var(--xh-text-secondary);
  letter-spacing: .2px;
  transition: border-color var(--xh-transition), color var(--xh-transition), background var(--xh-transition);
}
.xk-hub-quick-link:hover {
  border-color: var(--xh-border-light);
  color: var(--xh-text);
  background: rgba(255,255,255,.03);
}
.xk-hub-quick-link svg {
  width: 16px;
  height: 16px;
  color: var(--xh-text-muted);
  flex-shrink: 0;
}

/* ================= TRUST ================= */
.xk-hub-trust {
  position: relative;
  z-index: 1;
  padding: 56px 0;
  border-top: 1px solid var(--xh-border);
}
.xk-hub-trust-inner {
  max-width: var(--xh-max-w);
  margin: 0 auto;
  padding: 0 var(--xh-container-pad);
}
.xk-hub-trust-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-top: 28px;
}
.xk-hub-trust-item {
  text-align: center;
  padding: 24px 16px;
  border-radius: var(--xh-radius-lg);
  border: 1px solid var(--xh-border);
  background: var(--xh-bg-card);
  transition: border-color var(--xh-transition), transform var(--xh-transition);
}
.xk-hub-trust-item:hover {
  border-color: var(--xh-border-light);
  transform: translateY(-2px);
}
.xk-hub-trust-icon {
  width: 48px;
  height: 48px;
  margin: 0 auto 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
}
.xk-hub-trust-icon svg { width: 22px; height: 22px; }
.xk-hub-trust-icon--sync  { background: rgba(32,176,184,.10); border: 1px solid rgba(32,176,184,.28); color: var(--xh-teal); }
.xk-hub-trust-icon--check { background: rgba(32,168,104,.10); border: 1px solid rgba(32,168,104,.28); color: var(--xh-green); }
.xk-hub-trust-icon--lang  { background: rgba(42,125,225,.10); border: 1px solid rgba(42,125,225,.28); color: var(--xh-blue-light); }
.xk-hub-trust-icon--users { background: rgba(232,132,30,.10); border: 1px solid rgba(232,132,30,.28); color: var(--xh-orange); }

.xk-hub-trust-item h4 {
  font-size: 14px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .4px;
  color: #fff;
  margin: 0 0 6px;
}
.xk-hub-trust-item p {
  font-size: 13px;
  color: var(--xh-text-muted);
  line-height: 1.5;
  margin: 0;
}

/* ================= HELP CTA ================= */
.xk-hub-help {
  position: relative;
  z-index: 1;
  padding: 0 0 64px;
}
.xk-hub-help-inner {
  max-width: var(--xh-max-w);
  margin: 0 auto;
  padding: 0 var(--xh-container-pad);
}
.xk-hub-help-card {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 32px;
  align-items: center;
  padding: 40px 36px;
  border-radius: var(--xh-radius-lg);
  border: 1px solid var(--xh-border-light);
  background: linear-gradient(135deg, rgba(42,125,225,.06) 0%, rgba(232,132,30,.04) 100%);
  overflow: hidden;
  position: relative;
}
.xk-hub-help-content h2 {
  font-size: 22px;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: #fff;
  margin: 0 0 10px;
}
.xk-hub-help-content p {
  font-size: 15px;
  color: var(--xh-text-secondary);
  margin: 0 0 24px;
  line-height: 1.6;
  max-width: 440px;
}
.xk-hub-help-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}
.xk-hub-help-art {
  border-radius: var(--xh-radius);
  overflow: hidden;
  aspect-ratio: 16/10;
  border: 1px solid var(--xh-border);
  background: linear-gradient(135deg, #0a1428 0%, #1a2848 100%);
  display: flex;
  align-items: center;
  justify-content: center;
}
.xk-hub-help-art svg {
  width: 40px;
  height: 40px;
  color: var(--xh-text-muted);
  opacity: .2;
}

/* ================= RESPONSIVE ================= */
@media (max-width: 1100px) {
  .xk-hub-hero-inner { grid-template-columns: 1fr 320px; gap: 32px; }
  .xk-hub-sec-grid   { grid-template-columns: repeat(3, 1fr); }
  .xk-hub-pop-grid   { grid-template-columns: repeat(3, 1fr); }
  .xk-hub-pop-grid .xk-hub-pop-card:nth-child(n+4) { display: none; }
}
@media (max-width: 768px) {
  .xk-hub-hero { padding: 36px 0 40px; }
  .xk-hub-hero-inner { padding: 0 20px; grid-template-columns: 1fr; gap: 28px; }
  .xk-hub-hero-art { max-width: 400px; }
  .xk-hub-sections-inner { padding: 0 20px; }
  .xk-hub-sec-grid { grid-template-columns: 1fr 1fr; }
  .xk-hub-popular-inner { padding: 0 20px; }
  .xk-hub-pop-grid { grid-template-columns: 1fr 1fr; }
  .xk-hub-pop-grid .xk-hub-pop-card:nth-child(n+4) { display: block; }
  .xk-hub-pop-grid .xk-hub-pop-card:nth-child(n+5) { display: none; }
  .xk-hub-dual-inner { padding: 0 20px; grid-template-columns: 1fr; }
  .xk-hub-trust-inner { padding: 0 20px; }
  .xk-hub-trust-grid { grid-template-columns: 1fr 1fr; }
  .xk-hub-help-inner { padding: 0 20px; }
  .xk-hub-help-card { grid-template-columns: 1fr; padding: 28px 24px; }
  .xk-hub-help-art { max-width: 360px; }
  .xk-hub-facts { gap: 8px; }
  .xk-hub-fact { padding: 6px 10px; }
  .xk-hub-fact-val { font-size: 15px; }
}
@media (max-width: 480px) {
  .xk-hub-hero-inner { padding: 0 16px; }
  .xk-hub-sections-inner, .xk-hub-popular-inner, .xk-hub-dual-inner, .xk-hub-trust-inner, .xk-hub-help-inner { padding: 0 16px; }
  .xk-hub-sec-grid { grid-template-columns: 1fr; }
  .xk-hub-pop-grid { grid-template-columns: 1fr; }
  .xk-hub-pop-grid .xk-hub-pop-card { display: block; }
  .xk-hub-trust-grid { grid-template-columns: 1fr; }
  .xk-hub-quick-grid { grid-template-columns: 1fr; }
  .xk-hub-help-card { padding: 24px 18px; }
  .xk-hub-help-content h2 { font-size: 18px; }
  .xk-hub-help-actions { flex-direction: column; }
  .xk-hub-help-actions .xh-btn { width: 100%; justify-content: center; }
  .xk-hub-facts { display: grid; grid-template-columns: 1fr 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  .xk-hub-sec-card, .xk-hub-pop-card, .xk-hub-trust-item, .xk-hub-new-item, .xk-hub-quick-link { transition: none; }
}