/* Reset browser defaults so layout is predictable */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* Page container: readable line length, centered */
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI",
                 Roboto, sans-serif;
    line-height: 1.6;
    color: #222;
    background: #fafafa;
    max-width: 720px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

/* Header */
header {
    border-bottom: 1px solid #ddd;
    padding-bottom: 1rem;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

/* Navigation links */
nav a {
    margin-right: 1rem;
    color: #0066cc;
    text-decoration: none;
}

nav a:hover {
    text-decoration: underline;
}

/* Headings */
main h2 { font-size: 1.3rem; margin-bottom: 1rem; }
main h3 { font-size: 1.1rem; margin: 1.5rem 0 0.5rem; }
main h4 { font-size: 1rem; margin-bottom: 0.25rem; }

/* Spacing */
main p { margin-bottom: 1rem; }
main section { margin-bottom: 2rem; }
main article { margin-bottom: 1.5rem; }
ul { padding-left: 1.5rem; margin-bottom: 1rem; }

/* Links */
a { color: #0066cc; }

/* Footer */
footer {
    border-top: 1px solid #ddd;
    padding-top: 1rem;
    margin-top: 2rem;
    color: #888;
    font-size: 0.9rem;
}