/* Shelf Math - Shared Stylesheet */
:root {
  --green: #2e7d32;
  --green-light: #e8f5e9;
  --green-mid: #4caf50;
  --gray-dark: #212121;
  --gray-mid: #555;
  --gray-light: #f5f5f5;
  --border: #ddd;
  --white: #fff;
  --font: 'Georgia', serif;
  --sans: 'Segoe UI', Arial, sans-serif;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: var(--sans); font-size: 18px; color: var(--gray-dark); background: #fafafa; line-height: 1.7; }
a { color: var(--green); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Header */
header { background: var(--green); color: #fff; padding: 0 20px; }
.header-inner { max-width: 1100px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; padding: 14px 0; }
.logo { font-size: 1.6rem; font-weight: 700; color: #fff; letter-spacing: -0.5px; }
.logo span { color: #a5d6a7; }
nav a { color: rgba(255,255,255,0.9); margin-left: 24px; font-size: 1rem; font-weight: 500; }
nav a:hover { color: #fff; text-decoration: none; border-bottom: 2px solid #a5d6a7; }

/* Hero banner for articles */
.article-hero { width: 100%; height: 340px; object-fit: cover; display: block; }
.article-hero-wrap { position: relative; overflow: hidden; max-height: 340px; }
.article-hero-wrap::after { content: ''; position: absolute; inset: 0; background: linear-gradient(to bottom, transparent 40%, rgba(0,0,0,0.45)); }

/* Article layout */
.article-container { max-width: 820px; margin: 0 auto; padding: 40px 20px 60px; }
.article-meta { font-size: 0.9rem; color: #888; margin-bottom: 8px; }
.article-title { font-size: 2rem; font-weight: 700; line-height: 1.3; margin-bottom: 10px; font-family: var(--font); }
.article-byline { font-size: 0.95rem; color: #666; margin-bottom: 28px; padding-bottom: 20px; border-bottom: 1px solid var(--border); }
.article-body h2 { font-size: 1.4rem; margin: 36px 0 12px; color: var(--green); font-family: var(--font); }
.article-body p { margin-bottom: 18px; font-size: 1.05rem; }
.article-body ul, .article-body ol { margin: 12px 0 20px 28px; }
.article-body li { margin-bottom: 8px; font-size: 1.05rem; }

/* Callout box */
.callout { background: var(--green-light); border-left: 4px solid var(--green); border-radius: 6px; padding: 20px 24px; margin: 32px 0; }
.callout p { margin: 0; font-size: 1rem; }
.callout a { font-weight: 700; }

/* Data table */
.data-table { width: 100%; border-collapse: collapse; margin: 24px 0; font-size: 0.97rem; }
.data-table th { background: var(--green); color: #fff; padding: 12px 14px; text-align: left; }
.data-table td { padding: 11px 14px; border-bottom: 1px solid var(--border); }
.data-table tr:nth-child(even) td { background: var(--gray-light); }
.winner { color: var(--green); font-weight: 700; }

/* Footer */
footer { background: #222; color: #aaa; text-align: center; padding: 30px 20px; font-size: 0.9rem; }
footer a { color: #ccc; }

/* Page shell layout */
.page-wrap { max-width: 1100px; margin: 0 auto; padding: 0 20px; }

/* Breadcrumb */
.breadcrumb { font-size: 0.85rem; color: #888; padding: 14px 0 0; margin-bottom: 4px; }
.breadcrumb a { color: #888; }

/* Responsive */
@media (max-width: 600px) {
  .header-inner { flex-direction: column; gap: 10px; text-align: center; }
  nav a { margin: 0 10px; font-size: 0.95rem; }
  .article-title { font-size: 1.5rem; }
  .article-hero { height: 200px; }
}