/**
 * KH Core V4.1 — Design System (single source of truth)
 * No values outside defined tokens.
 */

:root {
  /* Colors */
  --bg: #0b1021;
  --surface: #111827;
  --card: rgba(15, 23, 42, 0.65);
  --primary: #3b82f6;
  --accent: #00d4ff;
  --text: #f8fafc;
  --muted: #94a3b8;
  --border: rgba(255, 255, 255, 0.08);

  /* Spacing — only these */
  --kh-space-8: 8px;
  --kh-space-16: 16px;
  --kh-space-24: 24px;
  --kh-space-32: 32px;
  --kh-space-48: 48px;
  --kh-space-64: 64px;

  /* Radius — only these */
  --kh-radius-sm: 12px;
  --kh-radius-md: 18px;
  --kh-radius-lg: 24px;

  /* Typography */
  --font-ui: "Inter", system-ui, sans-serif;
  --font-heading: "Plus Jakarta Sans", system-ui, sans-serif;
  --font-reading: "Merriweather", Georgia, serif;
  --font-weight-logo: 800;
  --font-weight-title: 700;

  /* Elevation */
  --kh-shadow-soft: 0 8px 24px rgba(0, 0, 0, 0.28);
  --kh-shadow-hover: 0 12px 32px rgba(59, 130, 246, 0.14);

  /* Motion */
  --kh-ease: 0.28s ease;
  --kh-lift: translateY(-4px) scale(1.01);

  /* Layout aliases */
  --radius-sm: var(--kh-radius-sm);
  --radius-md: var(--kh-radius-md);
  --radius-lg: var(--kh-radius-lg);
  --grid-gap: var(--kh-space-16);

  /* Ratios */
  --kh-ratio-hero: 16 / 9;
  --kh-ratio-card: 4 / 5;
  --kh-ratio-slider: 16 / 9;

  /* Components */
  --kh-header-h: 72px;
  --kh-card-width: 220px;
  --kh-card-body-h: 88px;
}

/* ─── Base ─── */
html {
  background: var(--bg);
  color: var(--text);
}

body.kh-core-v2,
body.kh-v3,
body.kh-v4,
body.kh-ds-v41 {
  font-family: var(--font-ui);
  font-size: 15px;
  line-height: 1.5;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

body.kh-ds-v41 h1,
body.kh-ds-v41 h2,
body.kh-ds-v41 h3,
body.kh-ds-v41 .kh-block__title,
body.kh-ds-v41 .kh-section__title {
  font-family: var(--font-heading);
  font-weight: var(--font-weight-title);
  color: var(--text);
  letter-spacing: -0.02em;
}

/* Surface panel — shared by sidebar, blocks, search */
.kh-surface {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--kh-radius-md);
  box-shadow: var(--kh-shadow-soft);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.kh-surface--lift {
  transition: transform var(--kh-ease), box-shadow var(--kh-ease);
}

.kh-surface--lift:hover {
  transform: var(--kh-lift);
  box-shadow: var(--kh-shadow-hover);
}

/* Reveal — always visible */
.kh-reveal {
  opacity: 1 !important;
  transform: none !important;
}

/* Section spacing */
.kh-section {
  margin: 0;
  padding: 0;
}

.kh-section + .kh-section {
  margin-top: 0;
}

.kh-block__head,
.kh-section__head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--kh-space-16);
  margin-bottom: var(--kh-space-16);
}

.kh-block__title,
.kh-section__title {
  margin: 0;
  font-size: 1.25rem;
}

/* Reading */
body.kh-ds-v41 .kh-article__reading,
body.kh-ds-v41 .entry-content {
  font-family: var(--font-reading);
  font-size: var(--reading-size, 19px);
  line-height: var(--reading-leading, 1.9);
  color: var(--text);
}

body.kh-ds-v41 .kh-article-header {
  margin-bottom: var(--kh-space-32);
  padding-bottom: var(--kh-space-24);
  border-bottom: 1px solid var(--border);
}

body.kh-ds-v41 .kh-article-header__title {
  font-family: var(--font-heading);
  font-weight: var(--font-weight-title);
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  line-height: 1.2;
  margin: var(--kh-space-16) 0;
}

body.kh-ds-v41 .kh-badge {
  display: inline-block;
  padding: var(--kh-space-8) var(--kh-space-16);
  border-radius: var(--kh-radius-sm);
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid var(--border);
  color: var(--accent);
  font-size: 12px;
  font-weight: 600;
  text-decoration: none;
}

/* ─── Header 72px ─── */
.kh-header {
  position: sticky;
  top: 0;
  z-index: 200;
  background: rgba(11, 16, 33, 0.88);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
}

.kh-header__inner {
  display: flex;
  align-items: center;
  gap: var(--kh-space-16);
  min-height: var(--kh-header-h);
  max-height: var(--kh-header-h);
  padding: 0 var(--kh-space-24);
  max-width: var(--kh-v4-container, 1440px);
  margin: 0 auto;
}

.kh-logo,
.kh-brand {
  display: flex;
  align-items: center;
  gap: var(--kh-space-16);
  text-decoration: none;
  color: inherit;
  flex-shrink: 0;
}

.kh-logo__mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--kh-radius-sm);
  background: linear-gradient(135deg, var(--primary), var(--accent));
  font-family: var(--font-heading);
  font-weight: var(--font-weight-logo);
  font-size: 14px;
  color: var(--text);
}

.kh-brand__title,
.kh-logo__text {
  font-family: var(--font-heading);
  font-weight: var(--font-weight-logo);
  font-size: 1rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  line-height: 1.15;
}

.kh-brand__slogan {
  display: block;
  font-family: var(--font-ui);
  font-size: 11px;
  font-weight: 500;
  color: var(--muted);
  letter-spacing: 0.04em;
  margin-top: 2px;
  text-transform: none;
}

.kh-header__search {
  flex: 1;
  max-width: 420px;
  position: relative;
}

.kh-search--premium,
.kh-search--v4 {
  display: flex;
  align-items: center;
  gap: var(--kh-space-8);
  padding: 0 var(--kh-space-16);
  min-height: 44px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--kh-radius-md);
  box-shadow: none;
}

.kh-search--premium .kh-search__input,
.kh-search--v4 .kh-search__input {
  flex: 1;
  min-width: 0;
  border: none;
  background: transparent;
  color: var(--text);
  padding: var(--kh-space-8) 0;
  font-family: var(--font-ui);
}

.kh-search--premium .kh-search__results,
.kh-search--v4 .kh-search__results {
  position: absolute;
  top: calc(100% + var(--kh-space-8));
  left: 0;
  right: 0;
  z-index: 100;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--kh-radius-md);
  box-shadow: var(--kh-shadow-soft);
  max-height: 360px;
  overflow-y: auto;
  padding: var(--kh-space-8);
}

.kh-header__nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  padding: var(--kh-space-8) var(--kh-space-16);
  border-radius: var(--kh-radius-sm);
  transition: color var(--kh-ease), background var(--kh-ease);
}

.kh-header__nav a:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.04);
}

/* ─── Ticker ─── */
.kh-ticker {
  display: flex;
  align-items: center;
  gap: var(--kh-space-16);
  padding: var(--kh-space-8) var(--kh-space-24);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  max-width: 100%;
}

.kh-ticker__label {
  font-family: var(--font-heading);
  font-weight: var(--font-weight-logo);
  font-size: 11px;
  color: var(--accent);
  letter-spacing: 0.12em;
}

.kh-ticker__viewport {
  flex: 1;
  overflow: hidden;
}

.kh-ticker__item {
  display: inline-block;
  margin-right: var(--kh-space-32);
  color: var(--muted);
  text-decoration: none;
  font-size: 13px;
  white-space: nowrap;
}

.kh-ticker__item:hover {
  color: var(--text);
}

/* ─── Sidebar (supportive) ─── */
.kh-sidebar--v4 {
  display: flex;
  flex-direction: column;
  gap: var(--kh-space-16);
  width: 100%;
  font-size: 14px;
}

.kh-sidebar--v4 .kh-sidebar-card {
  padding: var(--kh-space-16);
}

.kh-sidebar--v4 .kh-sidebar-card__title {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 var(--kh-space-16);
}

.kh-sidebar--v4 .kh-sidebar-story {
  display: flex;
  gap: var(--kh-space-8);
  padding: var(--kh-space-8) 0;
  text-decoration: none;
  color: inherit;
  border-radius: var(--kh-radius-sm);
  transition: background var(--kh-ease);
}

.kh-sidebar--v4 .kh-sidebar-story:hover {
  background: rgba(255, 255, 255, 0.03);
}

.kh-sidebar--v4 .kh-sidebar-story img {
  width: 40px;
  height: 48px;
  object-fit: cover;
  border-radius: var(--kh-radius-sm);
  flex-shrink: 0;
}

.kh-sidebar-tube {
  display: block;
  padding: var(--kh-space-16);
  text-align: center;
  text-decoration: none;
  border-radius: var(--kh-radius-md);
  background: rgba(0, 212, 255, 0.08);
  border: 1px solid rgba(0, 212, 255, 0.2);
  color: var(--text);
  font-weight: 600;
  transition: transform var(--kh-ease);
}

.kh-sidebar-tube:hover {
  transform: var(--kh-lift);
}

body.kh-ds-v41.kh-layout-article .sidebar {
  opacity: 0.92;
}

/* ─── Footer SaaS ─── */
.kh-layout-v4-footer-wrap {
  border-top: 1px solid var(--border);
  background: var(--surface);
}

.kh-footer--v4 {
  max-width: var(--kh-v4-container, 1440px);
  margin: 0 auto;
  padding: var(--kh-space-48) var(--kh-space-24) var(--kh-space-32);
}

.kh-footer--v4 .kh-footer__grid {
  display: grid;
  grid-template-columns: 1.5fr repeat(4, 1fr);
  gap: var(--kh-space-32);
}

.kh-footer--v4 .kh-footer__col h4 {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 var(--kh-space-16);
}

.kh-footer--v4 .kh-footer__col ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.kh-footer--v4 .kh-footer__col li + li {
  margin-top: var(--kh-space-8);
}

.kh-footer--v4 .kh-footer__col a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  transition: color var(--kh-ease);
}

.kh-footer--v4 .kh-footer__col a:hover {
  color: var(--text);
}

.kh-footer--v4 .kh-footer__tagline {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
  margin-top: var(--kh-space-8);
}

.kh-footer--v4 .kh-footer__bottom {
  margin-top: var(--kh-space-32);
  padding-top: var(--kh-space-24);
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--muted);
  font-size: 13px;
}

/* Trend ranked base (layout in sections.css skin) */
.kh-trend-ranked {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--kh-space-16);
}

.kh-trend-ranked__item {
  display: flex;
  gap: var(--kh-space-16);
  align-items: center;
  padding: var(--kh-space-16);
  text-decoration: none;
  color: inherit;
  transition: transform var(--kh-ease), box-shadow var(--kh-ease);
}

.kh-trend-ranked__item:hover {
  transform: var(--kh-lift);
  box-shadow: var(--kh-shadow-hover);
}

.kh-trend-ranked__num {
  font-size: 2.25rem;
  font-weight: var(--font-weight-logo);
  line-height: 1;
  color: var(--accent);
  min-width: 44px;
}

.kh-long-reads {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--kh-space-16);
}

.kh-long-read {
  display: block;
  text-decoration: none;
  color: inherit;
  transition: transform var(--kh-ease);
}

.kh-long-read:hover {
  transform: var(--kh-lift);
}

@media (max-width: 1024px) {
  .kh-footer--v4 .kh-footer__grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--kh-space-24);
  }

  .kh-trend-ranked {
    grid-template-columns: 1fr;
  }
}