html { scroll-behavior: smooth; }

    body {
      font-family: 'Rajdhani', system-ui, sans-serif;
      background: var(--bg);
      color: var(--text);
      line-height: 1.65;
      -webkit-font-smoothing: antialiased;
    }

    h1, h2, h3 { font-family: 'Orbitron', 'Rajdhani', sans-serif; line-height: 1.15; }

    article.post h1 {
  font-size: clamp(1.6rem, 4vw, 2.3rem);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: .3px;
  margin-bottom: 14px;
  word-break: break-word;
}
article.post h1 span {
  color: var(--gold);
  text-shadow: 0 0 26px rgba(255,176,32,.35);
}
article.post h1::after {
  content: '';
  display: block;
  width: 70px; height: 4px;
  margin-top: 16px;
  border-radius: 4px;
  background: linear-gradient(90deg, var(--gold), var(--cyan));
}

    a { color: var(--cyan); text-decoration: none; transition: color .2s; }
    a:hover { color: var(--gold); }

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

    .wrap { max-width: var(--maxw); margin-inline: auto; padding-inline: 22px; }

    /* ============ TOPBAR / MENU RESPONSIVE ============ */
    header.topbar {
      position: sticky; top: 0; z-index: 50;
      background: rgba(10,11,20,.82);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--line);
    }
    .nav {
      display: flex; align-items: center; justify-content: space-between;
      gap: 18px; height: 70px;
    }
    /* logo trong menu (co lại) */
    .brand { display: flex; align-items: center; gap: 10px; font-family: 'Orbitron'; font-weight: 700; font-size: 1.25rem; letter-spacing: .5px; color: var(--text); }
    .brand .dot { color: var(--gold); }

    .menu { display: flex; align-items: center; gap: 6px; list-style: none; }
    .menu a {
      color: var(--muted); font-weight: 500; font-size: .95rem;
      padding: 9px 14px; border-radius: 8px;
    }
    .menu a:hover { color: var(--text); background: var(--surface-2); }

    .hamburger {
      display: none; background: none; border: 1px solid var(--line);
      color: var(--text); width: 44px; height: 44px; border-radius: 10px;
      cursor: pointer; font-size: 1.4rem;
    }

    @media (max-width: 820px) {
      .hamburger { display: block; }
      .menu {
        position: absolute; top: 70px; left: 0; right: 0;
        flex-direction: column; align-items: stretch; gap: 2px;
        background: var(--surface); border-bottom: 1px solid var(--line);
        padding: 12px 22px 20px; box-shadow: var(--shadow);
        display: none;
      }
      .menu.open { display: flex; }
      .menu a { padding: 12px 14px; }
    }

    /* ============ HERO + BACKGROUND IMAGE ============ */
    .hero {
      position: relative;
      /* 👉 THAY link ảnh của bạn ở url(...) bên dưới */
      background:
        linear-gradient(180deg, rgba(10,11,20,.55) 0%, rgba(10,11,20,.92) 100%),
        radial-gradient(1200px 500px at 70% -10%, rgba(34,211,238,.18), transparent),
        url('../images/cover.jpg')
        center/cover no-repeat;
      text-align: center;
      padding: 74px 0 96px;
      border-bottom: 1px solid var(--line);
    }

    /* logo 150px NẰM GIỮA */
    .hero-logo {
      width: 150px; height: 150px;
      margin: 0 auto 22px;
      display: block;
    }

    .eyebrow {
      display: inline-block; font-family: 'Orbitron'; font-weight: 600;
      font-size: .8rem; letter-spacing: 3px; text-transform: uppercase;
      color: var(--gold); border: 1px solid rgba(255,176,32,.4);
      padding: 6px 14px; border-radius: 999px; margin-bottom: 18px;
    }

    .hero h1 {
      font-size: clamp(2.1rem, 5.5vw, 3.6rem);
      font-weight: 700; margin-bottom: 16px;
    }
    .hero h1 span { color: var(--gold); }
    .hero p.lead { color: var(--muted); font-size: 1.1rem; max-width: 620px; margin: 0 auto 30px; }

    /* ============ THANH SEARCH RESPONSIVE (Ở GIỮA) ============ */
    .search {
      display: flex; gap: 8px; width: 100%; max-width: 560px;
      margin: 0 auto; background: var(--surface); padding: 8px;
      border: 1px solid var(--line); border-radius: 999px;
      box-shadow: var(--shadow);
    }
    .search input {
      flex: 1; min-width: 0; background: transparent; border: none; outline: none;
      color: var(--text); font-size: 1rem; padding: 10px 16px;
      font-family: inherit;
    }
    .search input::placeholder { color: var(--muted); }
    .search button {
      background: var(--gold); color: #241700; border: none;
      font-family: 'Orbitron'; font-weight: 700; font-size: .95rem;
      padding: 11px 24px; border-radius: 999px; cursor: pointer;
      white-space: nowrap; transition: transform .15s, filter .2s;
    }
    .search button:hover { filter: brightness(1.08); transform: translateY(-1px); }

    @media (max-width: 480px) {
      .search { flex-direction: column; border-radius: 18px; }
      .search button { border-radius: 12px; }
    }

    /* ============ NÚT WINDOW.OPEN ============ */
    .btn-open {
      display: inline-flex; align-items: center; gap: 8px;
      margin-top: 26px; background: linear-gradient(135deg, var(--cyan), #0891b2);
      color: #04222b; font-family: 'Orbitron'; font-weight: 700;
      font-size: 1rem; padding: 14px 30px; border: none; border-radius: 12px;
      cursor: pointer; transition: transform .15s, box-shadow .2s;
      box-shadow: 0 10px 30px rgba(34,211,238,.28);
    }
    .btn-open:hover { transform: translateY(-2px); box-shadow: 0 14px 38px rgba(34,211,238,.4); }

    /* ============ SECTIONS ============ */
    section.block { padding: 35px 0; }
    .section-head { text-align: center; margin-bottom: 42px; }
    .section-head h2 { font-size: clamp(1.6rem, 4vw, 2.3rem); margin-bottom: 10px; }
    .section-head p { color: var(--muted); max-width: 560px; margin: 0 auto; }

    /* Cards / features */
    .grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 20px; }
    .card {
      background: var(--surface); border: 1px solid var(--line);
      border-radius: var(--radius); padding: 26px;
    }
    .card h3 { font-size: 1.15rem; margin-bottom: 12px; color: var(--gold); }
    .card ul { list-style: none; }
    .card li { color: var(--muted); padding: 6px 0 6px 24px; position: relative; }
    .card li::before {
      content: '▸'; position: absolute; left: 0; color: var(--cyan);
    }

    /* Ảnh nằm giữa */
    figure.centered { text-align: center; margin: 40px auto; max-width: 820px; }
    figure.centered img {
      margin: 0 auto; border-radius: var(--radius);
      border: 1px solid var(--line); box-shadow: var(--shadow);
    }
    figure.centered figcaption { color: var(--muted); font-size: .9rem; margin-top: 12px; }

    /* Blockquote */
    blockquote {
      max-width: 760px; margin: 10px auto; background: var(--surface-2);
      border-left: 4px solid var(--gold); border-radius: 0 var(--radius) var(--radius) 0;
      padding: 26px 30px; font-size: 1.15rem; font-style: italic; color: var(--text);
    }
    blockquote footer { margin-top: 12px; font-style: normal; font-size: .9rem; color: var(--muted); }

    /* ============ TABLE ============ */
    .table-scroll { overflow-x: auto; border-radius: var(--radius); border: 1px solid var(--line); margin: 20px 0;}
    table { width: 100%; border-collapse: collapse; min-width: 560px; background: var(--surface); }
    thead th {
      background: var(--surface-2); color: var(--gold); font-family: 'Orbitron';
      text-align: left; padding: 14px 18px; font-size: .9rem; letter-spacing: .5px;
      border-bottom: 1px solid var(--line);
    }
    tbody td { padding: 14px 18px; border-bottom: 1px solid var(--line); color: var(--muted); }
    tbody tr:last-child td { border-bottom: none; }
    tbody tr:hover td { background: rgba(34,211,238,.05); color: var(--text); }
    .tag { display: inline-block; background: rgba(255,176,32,.14); color: var(--gold); padding: 2px 10px; border-radius: 999px; font-size: .8rem; }

    /* ============ ARTICLE ============ */
    article.post {
      max-width: 780px; margin: 0 auto;
      background: var(--surface); border: 1px solid var(--line);
      border-radius: var(--radius); padding: 40px 42px;
    }
    article.post h2 { font-size: 1.8rem; margin-bottom: 8px; }
    article.post .meta { color: var(--muted); font-size: .9rem; margin-bottom: 24px; }
    article.post h3 { font-size: 1.25rem; margin: 28px 0 10px; color: var(--cyan); }
    article.post p { margin-bottom: 16px; color: #cfd2e6; }
    article.post ul { margin: 0 0 16px 22px; color: #cfd2e6; }
    article.post ol { margin: 0 0 16px 22px; color: #cfd2e6; }
    article.post li { margin-bottom: 6px; }

    @media (max-width: 560px) { article.post { padding: 28px 22px; } }

    /* ============ FOOTER ============ */
    footer.site {
      border-top: 1px solid var(--line); background: var(--surface);
      padding: 40px 0; text-align: center; margin-top: 20px;
    }
    footer.site .brand { justify-content: center; margin-bottom: 12px; }
    footer.site p { color: var(--muted); font-size: .9rem; }
    footer.site nav { margin-top: 14px; display: flex; gap: 18px; justify-content: center; flex-wrap: wrap; }

    :focus-visible { outline: 2px solid var(--cyan); outline-offset: 2px; }
    @media (prefers-reduced-motion: reduce) { * { transition: none !important; scroll-behavior: auto; } }