/* Shares token names and values with index.html's :root, and copies its
   header rules verbatim (container, header, brand, ghost-link, theme-btn,
   langs), so the blog header is the same header, not a lookalike. */
:root {
  --bg: #ffffff;
  --bg-alt: #f6f9fc;
  --surface: #ffffff;
  --surface-2: #f9fbfd;
  --text: #0f1b2a;
  --text-2: #43566a;
  --muted: #6b7f92;
  --border: #e2eaf2;
  --border-strong: #cfdbe7;
  --accent: #0066cc;
  --accent-2: #00a4e4;
  --accent-ink: #ffffff;
  --shadow-sm: 0 1px 2px rgba(15, 27, 42, 0.04), 0 1px 3px rgba(15, 27, 42, 0.06);
  --glow: rgba(0, 102, 204, 0.16);
}
:root[data-theme="dark"] {
  --bg: #0a1018;
  --bg-alt: #0e1724;
  --surface: #111c2b;
  --surface-2: #162334;
  --text: #eaf1f9;
  --text-2: #b4c4d6;
  --muted: #8698ab;
  --border: #22334a;
  --border-strong: #2e4360;
  --accent: #55a6ff;
  --accent-2: #3fd0ff;
  --accent-ink: #06101c;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --glow: rgba(85, 166, 255, 0.24);
}
:root[data-theme="dark"] .icon-sun { display: none; }
:root:not([data-theme="dark"]) .icon-moon { display: none; }

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { max-width: 1140px; margin: 0 auto; padding: 0 1.5rem; }
.container-narrow { max-width: 760px; margin: 0 auto; padding: 0 1.5rem; }

/* ---- header, copied from index.html's own rules ---- */
header {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  border-bottom: 1px solid var(--border);
}
.header-row { display: flex; justify-content: space-between; align-items: center; gap: 1rem; padding: 0.85rem 0; }
.brand { font-weight: 800; font-size: 1.05rem; color: var(--text); display: flex; align-items: center; gap: 0.55rem; }
.brand a { color: inherit; }
.brand a:hover { text-decoration: none; }
.brand-mark {
  width: 28px; height: 28px; border-radius: 8px; flex-shrink: 0;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  display: grid; place-items: center; color: #fff; font-size: 0.72rem; font-weight: 800;
  box-shadow: 0 4px 12px var(--glow);
}
.brand-sub { color: var(--muted); font-weight: 400; font-size: 0.9rem; }
.header-tools { display: flex; align-items: center; gap: 0.5rem; }
.ghost-link {
  font-size: 0.9rem; color: var(--text-2); padding: 0.45rem 0.7rem;
  border-radius: 8px; border: 1px solid transparent;
}
.ghost-link:hover { text-decoration: none; background: var(--surface-2); border-color: var(--border); }
.theme-btn {
  width: 38px; height: 38px; border-radius: 10px; cursor: pointer;
  border: 1px solid var(--border); background: var(--surface);
  color: var(--text-2); display: grid; place-items: center;
  transition: background 160ms ease, border-color 160ms ease, transform 160ms ease;
}
.theme-btn:hover { background: var(--surface-2); border-color: var(--border-strong); transform: translateY(-1px); }
.theme-btn svg { width: 17px; height: 17px; }
.langs { display: inline-flex; gap: 1px; margin-inline-start: 0.2rem; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.lang { font-size: 0.74rem; font-weight: 700; letter-spacing: 0.02em; padding: 0.38rem 0.44rem; color: var(--muted); background: var(--surface); }
.lang:hover { text-decoration: none; color: var(--accent); background: var(--surface-2); }
.lang.on { color: var(--accent-ink); background: linear-gradient(135deg, var(--accent), var(--accent-2)); }
@media (max-width: 400px) { .langs { display: none; } }
@media (max-width: 480px) {
  .brand-sub { display: none; }
}
@media (max-width: 360px) {
  .header-tools .ghost-link { display: none; }
}

/* ---- blog content ---- */
.blog-index, .blog-article { padding-top: 2.5rem; padding-bottom: 4rem; }

.blog-meta {
  color: var(--muted);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  margin: 0 0 0.4rem;
}

h1 { font-size: 2rem; line-height: 1.25; margin: 0 0 1.5rem; }
.blog-article h1 { margin-bottom: 0.5rem; }
.blog-article h2 { font-size: 1.3rem; margin: 2rem 0 0.75rem; }
.blog-article p { color: var(--text-2); margin: 0 0 1.1rem; }
.blog-article ul { color: var(--text-2); margin: 0 0 1.1rem; padding-left: 1.3rem; }
.blog-article li { margin-bottom: 0.5rem; }

.blog-intro { color: var(--text-2); max-width: 54ch; margin-bottom: 2rem; }

.blog-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 1rem; }
.blog-card {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
  box-shadow: var(--shadow-sm);
}
.blog-card a { display: block; padding: 1.25rem 1.4rem; color: var(--text); }
.blog-card h2 { font-size: 1.1rem; margin: 0.2rem 0 0.4rem; }
.blog-card p:not(.blog-meta) { color: var(--text-2); margin: 0; font-size: 0.95rem; }

.blog-back { margin-top: 2.5rem; }