*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
    :root {
      --navy: var(--nav-bg); --navy-mid: var(--border); --navy-light: var(--bg-elevated);
      --white: #ffffff; --off-white: #f5f7fa;
      --green: var(--accent); --green-dark: var(--accent-hover);
      --text: #1a1e2e; --text-muted: #5a6480;
      --border: #e2e8f0; --radius: 0.5rem;
    }
    html { font-size: 16px; }
    body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif; color: var(--text); background: var(--off-white); line-height: 1.7; }
    .nav { position: sticky; top: 0; z-index: 100; background: var(--navy); border-bottom: 1px solid var(--navy-mid); padding: 0.75rem 0; }
    .nav-inner { display: flex; align-items: center; justify-content: space-between; max-width: 960px; margin: 0 auto; padding: 0 1.5rem; }
    .nav-logo { color: var(--white); text-decoration: none; font-size: 1.15rem; font-weight: 700; letter-spacing: -0.02em; }
    .nav-logo span { color: var(--green); }
    .nav-links { display: flex; align-items: center; gap: 1.5rem; }
    .nav-links a { color: rgba(255,255,255,0.75); text-decoration: none; font-size: 0.9rem; font-weight: 500; }
    .nav-links a:hover { color: var(--white); }
    .content { max-width: 720px; margin: 0 auto; padding: 3rem 1.5rem 4rem; }
    .content h1 { font-size: 2rem; color: var(--navy); margin-bottom: 0.5rem; }
    .content .date { font-size: 0.85rem; color: var(--text-muted); margin-bottom: 2rem; }
    .content h2 { font-size: 1.25rem; color: var(--navy); margin-top: 2rem; margin-bottom: 0.75rem; }
    .content p { margin-bottom: 1rem; }
    .content ul, .content ol { margin-bottom: 1rem; padding-left: 1.5rem; }
    .content li { margin-bottom: 0.4rem; }
    .content a { color: var(--green-dark); }
    .nav-cta { display: inline-block; background: var(--accent); color: #fff; text-decoration: none; font-weight: 600; font-size: 0.9rem; padding: 0.55rem 1.25rem; border-radius: 0.5rem; transition: background 0.2s; }
    .nav-cta:hover { background: var(--accent-hover); }
    .hamburger { display: none; align-items: center; justify-content: center; background: none; border: none; color: rgba(255,255,255,0.85); cursor: pointer; padding: 0.35rem; border-radius: 6px; }
    .hamburger svg { width: 22px; height: 22px; }
    .hamburger:hover { color: #fff; }
    .theme-toggle { background: none; border: none; color: rgba(255,255,255,0.7); cursor: pointer; padding: 0.35rem; display: flex; align-items: center; border-radius: 6px; }
    .theme-toggle svg { width: 18px; height: 18px; }
    .icon-sun { display: none; }
    [data-theme="dark"] .icon-moon { display: none; }
    [data-theme="dark"] .icon-sun { display: block; }
    .mobile-nav { display: none; flex-direction: column; background: var(--nav-bg); border-top: 1px solid var(--border); padding: 1rem 1.5rem; }
    .mobile-nav.open { display: flex; }
    .mobile-nav-link { color: rgba(255,255,255,0.8); text-decoration: none; font-size: 0.95rem; font-weight: 500; padding: 0.65rem 0; border-bottom: 1px solid rgba(255,255,255,0.06); }
    .mobile-nav-link:last-of-type { border-bottom: none; }
    .mobile-nav-cta { display: inline-block; background: var(--accent); color: #fff; text-align: center; text-decoration: none; font-weight: 600; font-size: 0.9rem; padding: 0.75rem 1.5rem; border-radius: 0.5rem; margin-top: 0.75rem; }
    @media (max-width: 760px) { .hamburger { display: flex; } .nav-links { display: none; } }
    @media (max-width: 640px) {
      .content h1 { font-size: 1.5rem; }
    }