:root {
  --color-primary: #0055A4; /* Màu cờ Pháp */
  --color-secondary: #EF4135;
  --color-text: #333333;
  --color-text-muted: #666666;
  --color-bg: #F8F9FA;
  --color-border: #E5E7EB;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;
  --font-main: 'Inter', sans-serif;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: var(--font-main); color: var(--color-text); line-height: 1.6; background-color: #fff; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.container--narrow { max-width: 800px; }

/* Header */
.site-header { border-bottom: 1px solid var(--color-border); padding: 16px 0; position: sticky; top: 0; background: #fff; z-index: 100; }
.site-header__inner { display: flex; align-items: center; justify-content: space-between; }
.site-logo { font-size: 1.5rem; font-weight: 800; color: var(--color-primary); text-decoration: none; }
.site-nav { display: flex; gap: 24px; align-items: center; }
.site-nav a { text-decoration: none; color: var(--color-text); font-weight: 500; transition: color 0.2s; }
.site-nav a:hover { color: var(--color-primary); }

/* Typography & Content */
.page-header { padding: 60px 0 40px; text-align: center; background: var(--color-bg); margin-bottom: 40px; }
.page-title { font-size: 2.5rem; color: var(--color-primary); margin-bottom: 16px; }
.content-body h2 { font-size: 1.75rem; color: var(--color-primary); margin: 32px 0 16px; border-bottom: 2px solid var(--color-bg); padding-bottom: 8px; }
.content-body h3 { font-size: 1.25rem; color: var(--color-secondary); margin: 24px 0 12px; }
.content-body p { margin-bottom: 16px; font-size: 1.1rem; }
.content-body ul { margin-bottom: 24px; padding-left: 24px; font-size: 1.1rem; }
.content-body li { margin-bottom: 8px; }

/* TOC */
.toc-box { background: var(--color-bg); padding: 24px; border-radius: var(--radius-md); margin: 32px 0; border: 1px solid var(--color-border); }
.toc-box h3 { margin-top: 0; color: var(--color-primary); font-size: 1.2rem; margin-bottom: 16px; }
.toc-box ul { list-style-type: none; padding-left: 0; margin-bottom: 0; }
.toc-box li { margin-bottom: 12px; }
.toc-box a { color: var(--color-text); text-decoration: none; font-weight: 500; }
.toc-box a:hover { color: var(--color-primary); text-decoration: underline; }

/* Author Box */
.author-box { display: flex; gap: 20px; background: var(--color-bg); padding: 24px; border-radius: var(--radius-md); margin-top: 48px; border-left: 4px solid var(--color-primary); align-items: center; }
.author-box__avatar { width: 80px; height: 80px; border-radius: 50%; overflow: hidden; background: var(--color-primary); flex-shrink: 0; }
.author-box__avatar img { width: 100%; height: 100%; object-fit: cover; }
.author-box__info h3 { margin-top: 0; margin-bottom: 4px; font-size: 1.2rem; }
.author-box__info p { margin-bottom: 8px; font-size: 0.95rem; color: var(--color-text-muted); }
.author-box__link { color: var(--color-primary); font-weight: 600; text-decoration: none; font-size: 0.9rem; }

/* Footer */
.site-footer { background: #111827; color: #fff; padding: 60px 0 24px; margin-top: 80px; }
.site-footer__grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.site-footer h4 { color: #fff; margin-bottom: 20px; font-size: 1.1rem; }
.site-footer ul { list-style: none; padding: 0; }
.site-footer ul li { margin-bottom: 12px; color: #9CA3AF; }
.site-footer ul a { color: #9CA3AF; text-decoration: none; transition: color 0.2s; }
.site-footer ul a:hover { color: #fff; }
.site-footer__bottom { padding-top: 24px; border-top: 1px solid #374151; display: flex; justify-content: space-between; color: #9CA3AF; font-size: 0.9rem; }
.footer-legal a { color: #9CA3AF; text-decoration: none; margin: 0 8px; }
.footer-legal a:hover { color: #fff; }