:root {
  --bg: #ffffff;
  --fg: #1a1a1f;
  --muted: #5b6470;
  --accent: #2563eb;
  --accent-2: #0ea5e9;
  --border: #e6e8ec;
  --card: #f7f9fc;
  --maxw: 720px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--font);
  color: var(--fg);
  background: var(--bg);
  line-height: 1.65;
  font-size: 18px;
}
.wrap { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.site-header { border-bottom: 1px solid var(--border); padding: 16px 0; position: sticky; top: 0; background: rgba(255,255,255,0.9); backdrop-filter: blur(6px); z-index: 10; }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; }
.brand { font-weight: 800; font-size: 22px; color: var(--fg); letter-spacing: -0.5px; }
.brand:hover { text-decoration: none; }
.brand-accent { color: var(--accent); }
.site-header nav a { margin-left: 18px; color: var(--muted); font-size: 16px; font-weight: 500; }

main { padding: 40px 0 64px; }

.hero { padding: 16px 0 8px; }
.hero h1 { font-size: 2.1rem; line-height: 1.15; letter-spacing: -1px; margin: 0 0 12px; }
.hero .tagline { font-size: 1.15rem; color: var(--muted); margin: 0 0 8px; max-width: 56ch; }
.hero .sub { color: var(--muted); font-size: 0.98rem; }

.article-list { list-style: none; padding: 0; margin: 32px 0 0; }
.article-list li { border-top: 1px solid var(--border); padding: 22px 0; }
.article-list li:last-child { border-bottom: 1px solid var(--border); }
.article-list h2 { font-size: 1.25rem; margin: 0 0 6px; line-height: 1.25; }
.article-list h2 a { color: var(--fg); }
.article-list h2 a:hover { color: var(--accent); text-decoration: none; }
.article-list .excerpt { color: var(--muted); margin: 0 0 6px; font-size: 1rem; }
.article-list .meta { color: var(--muted); font-size: 0.85rem; }

article.post h1 { font-size: 2rem; line-height: 1.18; letter-spacing: -0.8px; margin: 0 0 10px; }
article.post .post-meta { color: var(--muted); font-size: 0.9rem; margin: 0 0 28px; padding-bottom: 18px; border-bottom: 1px solid var(--border); }
article.post h2 { font-size: 1.4rem; margin: 36px 0 12px; letter-spacing: -0.4px; }
article.post h3 { font-size: 1.15rem; margin: 28px 0 10px; }
article.post p { margin: 0 0 18px; }
article.post ul, article.post ol { margin: 0 0 18px; padding-left: 1.4em; }
article.post li { margin: 6px 0; }
article.post blockquote { border-left: 3px solid var(--accent); margin: 0 0 18px; padding: 4px 0 4px 18px; color: var(--muted); }
article.post strong { color: var(--fg); }
article.post hr { border: none; border-top: 1px solid var(--border); margin: 28px 0; }

.author-box { margin-top: 44px; padding: 22px; background: var(--card); border: 1px solid var(--border); border-radius: 10px; }
.author-box h3 { margin: 0 0 8px; font-size: 1.05rem; }
.author-box p { margin: 0; color: var(--muted); font-size: 0.95rem; }

.related { margin-top: 40px; }
.related h3 { font-size: 1rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); margin: 0 0 12px; }
.related ul { list-style: none; padding: 0; margin: 0; }
.related li { padding: 8px 0; border-top: 1px solid var(--border); }

.site-footer { border-top: 1px solid var(--border); padding: 28px 0 48px; margin-top: 40px; color: var(--muted); font-size: 0.9rem; }
.site-footer p { margin: 4px 0; }
.site-footer .why-line { font-style: italic; opacity: 0.85; margin-bottom: 10px; }
.muted { color: var(--muted); }

.note { background: var(--card); border: 1px solid var(--border); border-radius: 8px; padding: 14px 18px; font-size: 0.95rem; color: var(--muted); margin: 24px 0; }

@media (max-width: 560px) {
  body { font-size: 17px; }
  .hero h1 { font-size: 1.7rem; }
  article.post h1 { font-size: 1.6rem; }
}