/* exchange-series — clean dark technical theme */
:root {
  --bg: #0b0e14;
  --bg-soft: #11151f;
  --card: #141a26;
  --border: #1f2735;
  --fg: #e6e9ef;
  --muted: #8b93a7;
  --accent: #f0b90b;   /* crypto gold */
  --accent-2: #3b82f6;
  --code-bg: #0d1117;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  line-height: 1.75;
  font-size: 17px;
}
.wrap { max-width: 760px; margin: 0 auto; padding: 0 24px; }

/* header */
.site-header {
  border-bottom: 1px solid var(--border);
  background: var(--bg-soft);
  position: sticky; top: 0; z-index: 10;
}
.site-header .wrap {
  display: flex; align-items: center; justify-content: space-between;
  height: 60px;
}
.brand { display: flex; flex-direction: column; text-decoration: none; line-height: 1.3; }
.brand-zh { color: var(--fg); font-weight: 600; font-size: 15px; }
.brand-en { color: var(--muted); font-size: 11px; letter-spacing: 0.05em; }
nav a { color: var(--muted); text-decoration: none; margin-left: 18px; font-size: 14px; }
nav a:hover { color: var(--accent); }
nav a.lang-switch {
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 4px 12px;
  font-size: 13px;
  color: var(--accent);
}
nav a.lang-switch:hover { border-color: var(--accent); background: var(--card); }

/* hero */
.hero { padding: 64px 0 40px; }
.hero h1 { font-size: 30px; margin: 0 0 8px; line-height: 1.3; }
.hero-en { color: var(--accent); font-size: 15px; margin: 0 0 18px; font-style: italic; }
.hero-desc { color: var(--muted); font-size: 16px; max-width: 600px; }

/* article list */
.list { padding-bottom: 60px; }
.card {
  display: block;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px 24px;
  margin-bottom: 16px;
  text-decoration: none;
  color: inherit;
  transition: border-color .15s, transform .15s;
}
.card:hover { border-color: var(--accent); transform: translateY(-2px); }
.card-no { font-size: 12px; color: var(--accent); letter-spacing: 0.08em; margin-bottom: 6px; }
.card h2 { margin: 0 0 4px; font-size: 20px; }
.card-en { color: var(--muted); font-size: 14px; margin: 0 0 8px; }
.card-date { color: var(--muted); font-size: 12px; margin: 0; }

/* post page */
.post { padding: 48px 0 60px; }
.post-head { margin-bottom: 32px; padding-bottom: 24px; border-bottom: 1px solid var(--border); }
.series-no { color: var(--accent); font-size: 13px; letter-spacing: 0.08em; margin-bottom: 10px; }
.post-head h1 { font-size: 28px; margin: 0 0 8px; line-height: 1.35; }
.post-en { color: var(--accent); font-size: 14px; margin: 0 0 14px; font-style: italic; }
.post-meta { color: var(--muted); font-size: 13px; }

.post-body h2 {
  font-size: 21px; margin: 40px 0 14px; padding-top: 12px;
  border-top: 1px solid var(--border);
}
.post-body p { margin: 0 0 18px; }
.post-body strong { color: var(--accent); }
.post-body ul, .post-body ol { padding-left: 24px; margin: 0 0 18px; }
.post-body li { margin-bottom: 8px; }
.post-body blockquote {
  margin: 20px 0; padding: 12px 18px;
  border-left: 3px solid var(--accent);
  background: var(--bg-soft);
  color: var(--muted);
  border-radius: 0 8px 8px 0;
}
.post-nav { margin-top: 48px; }
.post-nav a { color: var(--accent); text-decoration: none; font-size: 15px; }
.post-nav a:hover { text-decoration: underline; }

/* about */
.about { padding: 48px 0 60px; }
.about h1 { font-size: 28px; }
.about h2 { font-size: 19px; margin-top: 32px; color: var(--accent); }

/* footer */
.site-footer { border-top: 1px solid var(--border); padding: 28px 0; }
.site-footer p { color: var(--muted); font-size: 13px; margin: 0; }
.site-footer a { color: var(--muted); }
.site-footer a[href^="mailto"] { color: var(--accent); }
.site-footer a[href^="mailto"]:hover { text-decoration: underline; }

/* responsive */
@media (max-width: 600px) {
  .hero { padding: 40px 0 28px; }
  .hero h1 { font-size: 24px; }
  .post-head h1 { font-size: 22px; }
  .brand-en { display: none; }
}