:root{--color-primary:#111827;--color-secondary:#6b7280;--color-accent:#2563eb;--color-background:#ffffff;--font-body:system-ui,-apple-system,"Segoe UI",sans-serif;--font-heading:system-ui,-apple-system,"Segoe UI",sans-serif}*{box-sizing:border-box}body{margin:0;font-family:var(--font-body);color:var(--color-primary);background:var(--color-background);line-height:1.6}h1,h2,h3,h4{font-family:var(--font-heading);line-height:1.2}a{color:var(--color-accent)}