:root {
      --bg: #f8f9fb;
      --text: #1f2937;
      --muted: #6b7280;
      --accent: #2563eb;
      --accent-hover: #1d4ed8;
      --dim-footer: #1e293b;
      --container-max: 1280px;
      --gutter: 20px;
      font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial;
    }

    html, body {
      height: 100%;
      margin: 0;
      background: var(--bg);
      color: var(--text);
      scroll-behavior: smooth;
    }

    /* Floating translucent header */
    header.app-header {
      position: fixed;
      top: 20px; left: 50%; transform: translateX(-50%);
      width: calc(100% - 40px);
      max-width: 1100px;
      z-index: 1000;
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 10px 22px;
      border-radius: 16px;
      background: rgba(255, 255, 255, 0.25);
      backdrop-filter: blur(2px) saturate(160%);
      -webkit-backdrop-filter: blur(2px) saturate(100%);
      border: 1px solid rgba(255,255,255,0.5);
      box-shadow: 0 4px 24px rgba(15,23,42,0.08);
      transition: all 0.3s ease;
    }

    header.app-header.scrolled {
      background: rgba(255,255,255,0.25);
      top: 0;
      border-radius: 0;
      box-shadow: 0 4px 18px rgba(15,23,42,0.1);
    }

    header .brand {
      display: flex;
      align-items: center;
      gap: 10px;
    }

    header .brand .logo {
      width: 36px;
      height: 36px;
      border-radius: 8px;
      background: linear-gradient(135deg, var(--accent), #60a5fa);
      display: flex;
      align-items: center;
      justify-content: center;
      color: white;
      font-weight: 700;
    }

    header nav a {
      margin-left: 18px;
      text-decoration: none;
      color: var(--muted);
      font-weight: 600;
      transition: color 0.2s ease;
    }

    header nav a:hover {
      color: var(--accent);
    }

    /* Page container */
    .page-wrap {
      max-width: var(--container-max);
      margin: 120px auto 0;
      padding: 0 var(--gutter);
      box-sizing: border-box;
      overflow-x: hidden;
    }

    .grid {
      display: grid;
      grid-template-columns: 260px 1fr 260px;
      gap: 28px;
      align-items: start;
    }

    .card {
      background: #fff;
      border-radius: 12px;
      padding: 20px;
      box-shadow: 0 6px 20px rgba(15,23,42,0.08);
      transition: transform 0.2s ease, box-shadow 0.2s ease;
    }

    .card:hover {
      transform: translateY(-2px);
      box-shadow: 0 10px 28px rgba(15,23,42,0.1);
    }

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

    .sidebar .ad {
      height: 250px;
      border-radius: 10px;
      background: linear-gradient(180deg,#f9fafb,#f3f4f6);
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--muted);
      font-weight: 600;
      border: 1px dashed rgba(15,23,42,0.08);
    }

    main h1 {
      margin-top: 0;
      margin-bottom: 10px;
      font-size: 1.9rem;
      line-height: 1.3;
    }

    .meta {
      font-size: 0.9rem;
      color: var(--muted);
      margin-bottom: 16px;
    }

    article p {
      line-height: 1.75;
      color: #374151;
      margin-bottom: 16px;
    }

    .btn-primary {
      background: var(--accent);
      color: #fff;
      padding: 10px 16px;
      border-radius: 8px;
      text-decoration: none;
      font-weight: 600;
      transition: background 0.2s ease;
    }

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

    footer.site-footer {
      margin-top: 40px;
      background: var(--dim-footer);
      color: rgba(255,255,255,0.9);
      padding: 24px 20px;
      border-radius: 10px;
      text-align: center;
    }

    footer .links a {
      color: rgba(255,255,255,0.8);
      text-decoration: none;
      margin: 0 10px;
    }

    footer .links a:hover {
      color: #fff;
    }

    /* Responsive Design */
    @media (max-width: 1200px) {
      .grid { grid-template-columns: 220px 1fr 220px; }
    }

    @media (max-width: 980px) {
      .grid { grid-template-columns: 1fr 1fr; }
      .sidebar:nth-child(1) { display: none; }
    }

    @media (max-width: 760px) {
      header.app-header { width: calc(100% - 24px); top: 10px; }
      .page-wrap { margin-top: 90px; }
      .grid { grid-template-columns: 1fr; gap: 20px; }
      aside.sidebar { order: 3; }
    }

    @media (min-width: 1600px) {
      .page-wrap { max-width: 1500px; }
      .grid { grid-template-columns: 300px 1fr 300px; }
    }