/* ===== Design System (synced with main site) ===== */
    :root {
      --blue: #1d4ed8;
      --blue-light: #eff6ff;
      --blue-hover: #1e40af;
      --slate-900: #0f172a;
      --slate-800: #1e293b;
      --slate-700: #334155;
      --slate-500: #64748b;
      --slate-400: #94a3b8;
      --slate-200: #e2e8f0;
      --slate-100: #f1f5f9;
      --slate-50: #f8fafc;
      --white: #ffffff;
      --font-th: 'Prompt', sans-serif;
      --font-en: 'Inter', sans-serif;
    }
    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
    html { scroll-behavior: smooth; }
    body {
      font-family: var(--font-th);
      color: var(--slate-700);
      background: var(--white);
      -webkit-font-smoothing: antialiased;
    }

    /* ===== Navbar (same glass style as main site) ===== */
    .blog-nav {
      position: sticky; top: 0; z-index: 100;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--slate-200);
    }
    .blog-nav-inner {
      max-width: 1200px; margin: 0 auto;
      padding: 1rem 2rem;
      display: flex; justify-content: space-between; align-items: center;
    }
    .blog-nav-logo {
      display: inline-flex; align-items: center; gap: 8px;
      text-decoration: none; color: var(--slate-900);
      font-family: var(--font-en); font-weight: 800; font-size: 1.15rem;
    }
    .blog-nav-logo img { height: 32px; }
    .blog-nav-links { display: flex; gap: 1.5rem; align-items: center; }
    .blog-nav-links a {
      text-decoration: none; color: var(--slate-500);
      font-size: 0.95rem; font-weight: 600;
      transition: color 0.2s;
    }
    .blog-nav-links a:hover { color: var(--blue); }
    .blog-nav-links .nav-cta {
      background: var(--blue); color: var(--white);
      padding: 0.5rem 1.25rem; border-radius: 50px;
      font-weight: 700; font-size: 0.9rem;
      transition: background 0.2s, transform 0.2s;
    }
    .blog-nav-links .nav-cta:hover {
      background: var(--blue-hover); color: var(--white); transform: translateY(-1px);
    }

    /* ===== Breadcrumb ===== */
    .breadcrumb {
      max-width: 800px; margin: 0 auto;
      padding: 1.25rem 2rem 0;
      font-size: 0.85rem; color: var(--slate-400);
      font-family: var(--font-en);
    }
    .breadcrumb a { color: var(--slate-500); text-decoration: none; }
    .breadcrumb a:hover { color: var(--blue); text-decoration: underline; }
    .breadcrumb span { margin: 0 0.4rem; }

    /* ===== Article Header ===== */
    .article-header {
      max-width: 800px; margin: 0 auto;
      padding: 2.5rem 2rem 0;
    }
    .article-category {
      display: inline-block;
      background: var(--blue-light); color: var(--blue);
      font-size: 0.8rem; font-weight: 700;
      padding: 0.35rem 0.9rem; border-radius: 50px;
      text-transform: uppercase; letter-spacing: 0.02em;
      margin-bottom: 1.25rem;
    }
    .article-title {
      font-size: clamp(1.85rem, 4.5vw, 2.75rem);
      font-weight: 800; color: var(--slate-900);
      line-height: 1.25; letter-spacing: -0.02em;
      margin-bottom: 1rem;
    }
    .article-desc {
      font-size: 1.2rem; color: var(--slate-500);
      line-height: 1.6; font-weight: 400;
      margin-bottom: 2rem;
    }
    .article-meta {
      display: flex; align-items: center; gap: 1rem;
      padding-bottom: 2rem;
      border-bottom: 1px solid var(--slate-200);
    }
    .meta-avatar {
      width: 44px; height: 44px; border-radius: 50%;
      border: 2px solid var(--slate-100);
      object-fit: cover;
    }
    .meta-info { display: flex; flex-direction: column; }
    .meta-author {
      font-weight: 600; color: var(--slate-800); font-size: 0.95rem;
    }
    .meta-details {
      font-size: 0.85rem; color: var(--slate-400);
      font-family: var(--font-en);
    }

    /* ===== Cover Image ===== */
    .article-cover {
      max-width: 800px; margin: 2.5rem auto 0;
      padding: 0 2rem;
    }
    .article-cover img {
      width: 100%; height: auto;
      aspect-ratio: 16/9; object-fit: cover;
      border-radius: 12px;
      background: var(--slate-50);
    }

    /* ===== Table of Contents (inline, collapsible) ===== */
    .toc-block {
      max-width: 800px; margin: 2.5rem auto 0; padding: 0 2rem;
    }
    .toc-block details {
      background: var(--slate-50);
      border: 1px solid var(--slate-200);
      border-radius: 12px;
      overflow: hidden;
    }
    .toc-block summary {
      padding: 1rem 1.5rem;
      font-weight: 700; font-size: 0.95rem; color: var(--slate-800);
      cursor: pointer; list-style: none;
      display: flex; align-items: center; gap: 0.5rem;
    }
    .toc-block summary::before {
      content: '';
      display: inline-block;
      width: 18px; height: 18px;
      background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23334155' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M4 19.5v-15A2.5 2.5 0 0 1 6.5 2H20v20H6.5a2.5 2.5 0 0 1 0-5H20'/%3E%3C/svg%3E");
      background-size: cover;
    }
    .toc-block summary::-webkit-details-marker { display: none; }
    .toc-block details[open] summary { border-bottom: 1px solid var(--slate-200); }
    .toc-block .toc-list {
      padding: 1rem 1.5rem; list-style: none;
    }
    .toc-block .toc-list li { margin-bottom: 0.6rem; }
    .toc-block .toc-list a {
      color: var(--slate-500); text-decoration: none;
      font-size: 0.95rem; font-weight: 500;
      transition: color 0.2s;
    }
    .toc-block .toc-list a:hover { color: var(--blue); }

    /* ===== Article Body ===== */
    .article-body {
      max-width: 800px; margin: 0 auto;
      padding: 3rem 2rem 4rem;
      font-size: 1.1rem; line-height: 1.85;
      color: var(--slate-700);
    }
    .article-body h2 {
      font-size: 1.65rem; font-weight: 700; color: var(--slate-900);
      margin-top: 3rem; margin-bottom: 1rem;
      padding-top: 1.5rem; border-top: 1px solid var(--slate-200);
      line-height: 1.35;
    }
    .article-body h2:first-child { margin-top: 0; padding-top: 0; border-top: none; }
    .article-body h3 {
      font-size: 1.3rem; font-weight: 600; color: var(--slate-800);
      margin-top: 2rem; margin-bottom: 0.75rem;
    }
    .article-body p { margin-bottom: 1.5rem; }
    .article-body ul, .article-body ol {
      padding-left: 1.5rem; margin-bottom: 1.5rem;
    }
    .article-body li { margin-bottom: 0.6rem; }
    .article-body li::marker { color: var(--blue); }
    .article-body strong { color: var(--slate-900); font-weight: 600; }
    .article-body a {
      color: var(--blue); text-decoration: underline;
      text-underline-offset: 3px; text-decoration-thickness: 1px;
    }
    .article-body a:hover { color: var(--blue-hover); }
    .article-body img,
    .article-body .article-image {
      width: 100%; height: auto;
      border-radius: 12px; margin: 2rem 0;
    }

    /* ===== In-Article CTA (matches brand pill style) ===== */
    .in-article-cta {
      background: var(--blue-light);
      border: 1px solid #dbeafe;
      border-radius: 16px;
      padding: 1.75rem 2rem;
      margin: 2.5rem 0;
    }
    .in-article-cta strong {
      display: block; color: var(--slate-900);
      font-size: 1.1rem; margin-bottom: 0.5rem;
      display: flex; align-items: center;
    }
    .in-article-cta strong .inline-icon {
      color: var(--blue);
      margin-right: 8px;
    }
    .in-article-cta p { margin: 0; color: var(--slate-700); font-size: 1rem; }
    .in-article-cta a {
      color: var(--blue); font-weight: 600;
    }

    /* ===== FAQ ===== */
    .faq-section {
      max-width: 800px; margin: 0 auto;
      padding: 0 2rem 4rem;
    }
    .faq-section h2 {
      font-size: 1.65rem; font-weight: 700; color: var(--slate-900);
      margin-bottom: 1.5rem;
    }
    .faq-item {
      border: 1px solid var(--slate-200);
      border-radius: 12px;
      padding: 1.25rem 1.5rem;
      margin-bottom: 1rem;
      transition: border-color 0.2s;
    }
    .faq-item:hover { border-color: var(--blue); }
    .faq-item h3 {
      font-size: 1.05rem; font-weight: 600; color: var(--slate-900);
      margin-bottom: 0.5rem;
    }
    .faq-item p {
      font-size: 1rem; color: var(--slate-500); margin: 0; line-height: 1.7;
    }

    /* ===== Bottom CTA (matches main site style) ===== */
    .bottom-cta {
      background: linear-gradient(135deg, var(--blue-light) 0%, var(--white) 60%);
      border-top: 1px solid var(--slate-200);
      padding: 5rem 2rem;
      text-align: center;
    }
    .bottom-cta h2 {
      font-size: 1.85rem; font-weight: 800; color: var(--slate-900);
      margin-bottom: 0.75rem;
    }
    .bottom-cta p {
      color: var(--slate-500); font-size: 1.1rem;
      max-width: 480px; margin: 0 auto 2rem;
    }
    .bottom-cta .cta-btn {
      display: inline-block; text-decoration: none;
      background: var(--blue); color: var(--white);
      font-weight: 700; font-size: 1.05rem;
      padding: 0.95rem 2.5rem; border-radius: 50px;
      box-shadow: 0 8px 20px rgba(29,78,216,0.25);
      transition: background 0.2s, transform 0.2s;
    }
    .bottom-cta .cta-btn:hover {
      background: var(--blue-hover);
      transform: translateY(-2px);
    }

    /* ===== Footer ===== */
    .blog-footer {
      text-align: center; padding: 2rem;
      font-size: 0.85rem; color: var(--slate-400);
      border-top: 1px solid var(--slate-200);
      font-family: var(--font-en);
    }

    /* ===== Advanced SEO Elements ===== */
    .key-takeaways {
      background: var(--blue-light);
      border: 1px solid rgba(29, 78, 216, 0.1);
      border-radius: 12px;
      padding: 1.5rem 1.75rem;
      margin: 2.5rem 0;
      box-shadow: 0 4px 6px rgba(0,0,0,0.02);
    }
    .key-takeaways h3 {
      font-size: 1.15rem;
      color: var(--blue);
      margin-top: 0;
      margin-bottom: 1rem;
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }
    .key-takeaways h3::before {
      content: '⚡';
      font-size: 1.2rem;
    }
    .key-takeaways ul {
      margin: 0;
      padding-left: 1.2rem;
    }
    .key-takeaways li {
      margin-bottom: 0.5rem;
      color: var(--slate-700);
      font-weight: 500;
    }
    .key-takeaways li:last-child {
      margin-bottom: 0;
    }

    .article-body blockquote {
      border-left: 4px solid var(--blue);
      background: var(--slate-50);
      padding: 1.5rem 1.75rem;
      margin: 2.5rem 0;
      border-radius: 0 8px 8px 0;
      font-style: italic;
      color: var(--slate-700);
      font-size: 1.1rem;
    }
    .article-body blockquote p {
      margin: 0;
    }

    .article-table {
      width: 100%;
      border-collapse: collapse;
      margin: 2.5rem 0;
      background: var(--white);
      border-radius: 8px;
      overflow: hidden;
      box-shadow: 0 1px 3px rgba(0,0,0,0.05);
    }
    .article-table th, .article-table td {
      padding: 1rem 1.25rem;
      text-align: left;
      border-bottom: 1px solid var(--slate-200);
    }
    .article-table th {
      background: var(--slate-50);
      font-weight: 700;
      color: var(--slate-900);
      border-bottom: 2px solid var(--slate-200);
    }
    .article-table tr:last-child td {
      border-bottom: none;
    }
    .article-table tr:hover td {
      background: var(--slate-50);
    }

    /* ===== Post Navigation (Next/Prev) ===== */
    .post-navigation {
      max-width: 800px; margin: 0 auto 4rem; padding: 0 2rem;
      display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem;
    }
    .post-nav-card {
      display: block; text-decoration: none;
      padding: 1.5rem; border: 1px solid var(--slate-200);
      border-radius: 12px; background: var(--slate-50);
      transition: all 0.2s;
    }
    .post-nav-card:hover {
      border-color: var(--blue); background: var(--white);
      box-shadow: 0 4px 12px rgba(29,78,216,0.05);
    }
    .post-nav-label {
      display: block; font-size: 0.85rem; font-weight: 700;
      color: var(--blue); text-transform: uppercase;
      margin-bottom: 0.5rem; font-family: var(--font-en);
    }
    .post-nav-title {
      font-size: 1.05rem; font-weight: 600; color: var(--slate-900);
      line-height: 1.4;
    }

    /* ===== Sub Navigation (mobile secondary bar) ===== */
    .blog-nav-sub {
      display: none;
    }

    /* ===== Mobile ===== */
    @media (max-width: 768px) {
      .blog-nav-inner { padding: 0.75rem 1rem; }
      .blog-nav-logo img { height: 28px; }
      .blog-nav-logo span { font-size: 16px !important; }
      .blog-nav-links a:not(.nav-cta) { display: none; }
      .blog-nav-links .nav-cta { padding: 0.4rem 0.85rem; font-size: 0.8rem; }

      .blog-nav-sub {
        display: flex;
        justify-content: center;
        gap: 0.5rem;
        padding: 0.5rem 1rem;
        background: var(--slate-50);
        border-top: 1px solid var(--slate-200);
      }
      .blog-nav-sub a {
        display: inline-flex;
        align-items: center;
        gap: 0.3rem;
        text-decoration: none;
        font-size: 0.8rem;
        font-weight: 500;
        color: var(--slate-700);
        padding: 0.35rem 0.7rem;
        border-radius: 9999px;
        border: 1px solid var(--slate-200);
        background: var(--white);
        transition: all 0.2s;
      }
      .blog-nav-sub a:hover,
      .blog-nav-sub a:active {
        background: var(--blue-light);
        border-color: var(--blue);
        color: var(--blue);
      }
      .blog-nav-sub a svg {
        width: 14px;
        height: 14px;
        color: var(--slate-400);
      }

      .breadcrumb, .article-header, .article-cover,
      .toc-block, .article-body, .faq-section, .post-navigation { padding-left: 1.25rem; padding-right: 1.25rem; }
      .post-navigation { grid-template-columns: 1fr; margin-bottom: 2.5rem; }
      .article-title { font-size: 1.75rem; }
      .article-desc { font-size: 1.05rem; }
      .article-meta { flex-wrap: wrap; }
      .article-body { font-size: 1.05rem; }
      .bottom-cta { padding: 3.5rem 1.25rem; }
      .bottom-cta h2 { font-size: 1.5rem; }
    }