body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}
header {
    background: #217346; /* Excel Green */
    color: white;
    padding: 2rem;
    margin-bottom: 2rem;
    border-radius: 4px;
}
h1, h2, h3 { color: #1e1e1e; }
a { color: #217346; text-decoration: none; }
a:hover { text-decoration: underline; }
.article-list { list-style: none; padding: 0; }
.article-list li { margin-bottom: 0.5rem; border-bottom: 1px solid #eee; padding-bottom: 0.5rem; }
.breadcrumb { font-size: 0.9em; color: #666; margin-bottom: 1rem; }
code { background: #f4f4f4; padding: 2px 5px; border-radius: 3px; }
.error-box { background: #fff0f0; border-left: 4px solid #d32f2f; padding: 1rem; margin: 1rem 0; }
footer { margin-top: 4rem; padding-top: 1rem; border-top: 1px solid #ddd; font-size: 0.8em; text-align: center; }