:root{
  --blue: #2D9CDB;
  --blue-deep: #1E78B2;
  --ink: #0f172a;
  --muted: #475569;
  --border: rgba(15,23,42,.12);
  --card: rgba(255,255,255,.92);
  --shadow: 0 10px 28px rgba(2,8,23,.05);
  --radius: 18px;
}

*{ box-sizing: border-box; }
html,body{ margin:0; padding:0; }
body{
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
  color: var(--ink);
  background:
    radial-gradient(900px 600px at 1% 10%, rgba(45,156,219,.30), rgba(45,156,219,0) 70%),
    radial-gradient(900px 600px at 55% 10%, rgba(30,120,178,.20), rgba(30,120,178,0) 70%),
    linear-gradient(180deg, #f7fbff 0%, #ffffff 38%);
}

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

/* Header / Nav */
.site-header{
  background: linear-gradient(135deg, var(--blue) 0%, var(--blue-deep) 100%);
  color: #fff;
  padding-bottom: 14px;
  box-shadow: 0 18px 44px rgba(2,8,23,.12);
}
.nav{
  max-width: 1100px;
  margin: 0 auto;
  padding: 14px 16px;
  display:flex;
  align-items:center;
  justify-content: space-between;
  gap: 14px;
}
.brand{
  display:flex;
  align-items:center;
  gap: 10px;
}
.brand-logo{
  width: 128px;
  height: auto;
  display:block;
  filter: drop-shadow(0 10px 20px rgba(2,8,23,.22));
}
.brand-text{
  font-weight: 900;
  letter-spacing: -.02em;
  opacity: .95;
}
.nav-links{
  display:flex;
  align-items:center;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: flex-end;
}
.nav-link{
  padding: 9px 10px;
  border-radius: 14px;
  color: rgba(255,255,255,.92);
  font-weight: 800;
  font-size: 13px;
  border: 1px solid rgba(255,255,255,.22);
  background: rgba(255,255,255,.08);
}
.nav-link:hover{ background: rgba(255,255,255,.14); }
.nav-link.is-active{
  background: rgba(255,255,255,.22);
  border-color: rgba(255,255,255,.32);
}

.hero{
  max-width: 1100px;
  margin: 0 auto;
  padding: 12px 16px 6px;
}
.hero-inner{
  background: rgba(255,255,255,.10);
  border: 1px solid rgba(255,255,255,.20);
  border-radius: 22px;
  padding: 18px 16px;
}
.hero-title{
  margin: 0;
  font-size: 28px;
  font-weight: 950;
  letter-spacing: -.03em;
}
.hero-subtitle{
  margin: 8px 0 0;
  font-size: 14px;
  opacity: .92;
  line-height: 1.55;
}

/* Container */
.container{
  max-width: 1100px;
  margin: 0 auto;
  padding: 18px 16px 40px;
}

/* Controls */
.sr-only{
  position:absolute !important;
  width:1px;height:1px;
  padding:0;margin:-1px;
  overflow:hidden;clip:rect(0,0,0,0);
  white-space:nowrap;border:0;
}
.library-controls{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  margin: 0 0 14px;
}
.library-controls-left{
  display:flex;
  align-items:center;
  gap:12px;
  flex:1;
  min-width: 240px;
}
.library-search{
  flex: 1;
  min-width: 220px;
  height: 42px;
  padding: 0 12px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--card);
  box-shadow: 0 10px 22px rgba(2,8,23,.04);
  outline: none;
  font-size: 14px;
}
.library-search:focus{
  border-color: rgba(45,156,219,.55);
  box-shadow: 0 10px 22px rgba(45,156,219,.12);
}
.library-count{
  font-size: 13px;
  color: var(--muted);
  white-space: nowrap;
}
.select{
  height: 42px;
  padding: 0 12px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--card);
  font-weight: 800;
  font-size: 13px;
  color: var(--ink);
  box-shadow: 0 10px 22px rgba(2,8,23,.04);
}

/* Pills / Cards */
.pill{
  display:inline-flex;
  align-items:center;
  padding: 5px 9px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 900;
  color: var(--ink);
  background: rgba(255,255,255,.86);
  border: 1px solid rgba(255,255,255,.65);
  white-space: nowrap;
}
.kb-grid{
  display:grid;
  grid-template-columns: repeat(3, minmax(0,1fr));
  gap: 14px;
}
.kb-card{
  display:grid;
  gap: 10px;
  padding: 16px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--card);
  box-shadow: var(--shadow);
  transition: transform .15s ease, box-shadow .15s ease, border-color .15s ease;
}
.kb-card:hover{
  transform: translateY(-2px);
  border-color: rgba(45,156,219,.45);
  box-shadow: 0 16px 38px rgba(2,8,23,.08);
}
.kb-card-top{
  display:flex;
  align-items:flex-start;
  justify-content:space-between;
  gap: 10px;
}
.kb-card-title{
  font-size: 15px;
  font-weight: 950;
  letter-spacing: -.02em;
  line-height: 1.25;
}
.kb-card-desc{
  color: var(--muted);
  font-size: 13px;
  line-height: 1.55;
}
.kb-card-meta{
  color: rgba(71,85,105,.95);
  font-size: 12px;
}

/* Category header */
.section-head{ margin: 0 0 12px; }
.section-title{
  margin: 0;
  font-size: 20px;
  font-weight: 950;
  letter-spacing: -.03em;
}
.section-subtitle{
  margin: 8px 0 0;
  color: var(--muted);
  line-height: 1.6;
}

/* Article */
.article{
  background: rgba(255,255,255,.75);
  border: 1px solid var(--border);
  border-radius: 22px;
  box-shadow: 0 16px 44px rgba(2,8,23,.05);
  padding: 18px;
}
.article-head .kicker{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}
.article-title{
  margin: 0;
  font-size: 24px;
  font-weight: 950;
  letter-spacing: -.03em;
}
.article-desc{
  margin: 10px 0 0;
  color: var(--muted);
  line-height: 1.6;
}

.article-body{
  margin-top: 14px;
  line-height: 1.75;
  color: #0b1220;
}
.article-body h2{
  margin-top: 18px;
  font-size: 18px;
  letter-spacing: -.02em;
}
.article-body h3{
  margin-top: 16px;
  font-size: 15px;
}
.article-body p{ margin: 10px 0; }
.article-body ul{ margin: 8px 0 12px; padding-left: 18px; }
.article-body li{ margin: 4px 0; }
.article-body code{
  background: rgba(15,23,42,.06);
  border: 1px solid rgba(15,23,42,.10);
  padding: 2px 6px;
  border-radius: 10px;
  font-size: 12px;
}
.article-body blockquote{
  margin: 12px 0;
  padding: 10px 12px;
  border-left: 4px solid rgba(45,156,219,.55);
  background: rgba(45,156,219,.08);
  border-radius: 14px;
  color: var(--ink);
}

/* Callouts / grids */
.callout{
  margin-top: 14px;
  padding: 14px 14px 10px;
  border-radius: 18px;
  border: 1px solid rgba(45,156,219,.28);
  background: rgba(45,156,219,.10);
}
.callout h3{ margin: 0 0 8px; font-size: 14px; }
.callout ul{ margin: 0; padding-left: 18px; }
.callout li{ margin: 4px 0; }

.grid-2{
  margin-top: 14px;
  display:grid;
  grid-template-columns: repeat(2, minmax(0,1fr));
  gap: 14px;
}
.card{
  padding: 14px;
  border-radius: 18px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,.90);
  box-shadow: 0 10px 22px rgba(2,8,23,.04);
}
.card h3{ margin: 0 0 6px; font-size: 14px; }
.muted{ color: var(--muted); }
.tight{ margin: 0; padding-left: 18px; }

/* Related */
.related{ margin-top: 18px; }
.related h3{ margin: 0 0 10px; font-size: 14px; }
.related-grid{
  display:grid;
  grid-template-columns: repeat(2, minmax(0,1fr));
  gap: 12px;
}
.related-card{
  padding: 12px;
  border-radius: 16px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,.90);
  box-shadow: 0 10px 22px rgba(2,8,23,.04);
}
.related-card:hover{ border-color: rgba(45,156,219,.45); }
.related-title{ font-weight: 950; font-size: 13px; }
.related-desc{ color: var(--muted); font-size: 12px; margin-top: 6px; line-height: 1.55; }

/* Categories page */
.cat-grid{
  display:grid;
  grid-template-columns: repeat(3, minmax(0,1fr));
  gap: 14px;
}
.cat-card{
  padding: 16px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--card);
  box-shadow: var(--shadow);
}
.cat-card:hover{ border-color: rgba(45,156,219,.45); }
.cat-title{ font-weight: 950; font-size: 15px; letter-spacing: -.02em; }
.cat-desc{ color: var(--muted); font-size: 13px; line-height: 1.55; margin-top: 8px; }
.cat-meta{ color: rgba(71,85,105,.95); font-size: 12px; margin-top: 10px; }

/* Footer */
.footer{
  margin-top: 26px;
  padding: 18px 0 30px;
}
.footer-inner{
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 16px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap: 14px;
  color: var(--muted);
}
.footer a{ text-decoration: underline; text-underline-offset: 2px; }
.dot{ margin: 0 8px; opacity: .55; }

@media (max-width: 1100px){
  .kb-grid{ grid-template-columns: repeat(2, minmax(0,1fr)); }
  .cat-grid{ grid-template-columns: repeat(2, minmax(0,1fr)); }
}
@media (max-width: 860px){
  .nav{ flex-direction: column; align-items: flex-start; }
  .nav-links{ width: 100%; }
  .library-controls{ flex-direction: column; align-items: stretch; }
  .grid-2{ grid-template-columns: 1fr; }
  .kb-grid{ grid-template-columns: 1fr; }
  .cat-grid{ grid-template-columns: 1fr; }
  .related-grid{ grid-template-columns: 1fr; }
  .footer-inner{ flex-direction: column; align-items: flex-start; }
}