/* ============================================================
 * lib/design/louie.css
 * Common design tokens & components shared across
 * index.html · blog.html · learn.html
 *
 * Page-specific overrides (body extensions, page layouts,
 * reader prose, etc.) stay inline in each page's <style> block.
 * ============================================================ */

/* ─── Design tokens ─── */
:root {
  --bg: #1f1f1e;
  --surface: #2a2a29;
  --surface-high: #333332;
  --border: #3a3a39;
  --outline: #4a4a49;
  --text: #e8e8e8;
  --muted: #a1a1a0;
  --accent: #d97757;
  --accent-dim: rgba(217, 119, 87, 0.15);
  --accent-on: #ffb49d;
}

/* ─── Body base ─── */
body {
  font-family: 'JetBrains Mono', 'HarmonyOS Sans', 'PingFang SC', 'Microsoft YaHei', sans-serif !important;
  background-color: var(--bg);
  color: var(--text);
  -webkit-tap-highlight-color: transparent;
}

/* ─── Ripple ─── */
.ripple-surface { position: relative; overflow: hidden; }
.ripple {
  position: absolute; border-radius: 50%; transform: scale(0);
  animation: ripple 600ms linear; pointer-events: none;
  background-color: rgba(255, 255, 255, 0.15);
}
.ripple-primary .ripple { background-color: rgba(255, 255, 255, 0.3); }
.ripple-surface-variant .ripple { background-color: rgba(255, 255, 255, 0.08); }
@keyframes ripple { to { transform: scale(4); opacity: 0; } }

/* ─── M3 Card ─── */
.m3-card { transition: background-color 0.2s ease, box-shadow 0.2s ease, transform 0.2s ease; }
.m3-card:hover {
  background-color: var(--surface-high);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.28);
  transform: translateY(-3px);
}

/* ─── Navbar ─── */
#navbar {
  position: fixed; top: 0; left: 0; right: 0; z-index: 9999;
  display: flex; align-items: center; justify-content: space-between;
  height: 64px; padding: 0 24px;
  background: rgba(31, 31, 30, 0.95);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

.nav-brand-wrap { position: relative; }

#brand-dropdown-btn {
  position: relative; overflow: hidden;
  display: inline-flex; align-items: center;
  padding: 8px 12px; border-radius: 9999px;
  border: none; background: transparent;
  font-family: inherit; font-size: 18px; font-weight: 700;
  cursor: pointer; letter-spacing: 0.05em;
  transition: background 0.2s ease;
}
#brand-dropdown-btn:hover { background: var(--accent-dim); }
#brand-dropdown-btn .b-static { color: var(--text); }
#brand-dropdown-btn .b-page { color: rgba(232, 232, 232, 0.6); font-weight: 500; }

.b-dot {
  background: linear-gradient(90deg, #d97757, #ffb49d);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}

#brand-dropdown-icon {
  width: 16px; height: 16px; margin-left: 6px;
  color: rgba(232, 232, 232, 0.6); transition: transform 0.2s ease;
}

#brand-dropdown-menu {
  position: absolute; top: 100%; left: 0; margin-top: 8px;
  width: 192px; background: var(--surface); border-radius: 8px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4); border: 1px solid var(--border);
  padding: 8px 0; overflow: hidden;
  opacity: 0; pointer-events: none; transition: opacity 0.2s ease; z-index: 110;
}
#brand-dropdown-menu.is-open { opacity: 1; pointer-events: auto; }

.nav-dd-item {
  position: relative; overflow: hidden;
  display: block; padding: 12px 16px;
  font-size: 14px; font-weight: 500; text-decoration: none; color: var(--muted);
  transition: color 0.2s ease, background 0.2s ease;
}
.nav-dd-item:hover { color: var(--text); background: var(--surface-high); }
.nav-dd-item.nav-active { color: var(--accent); background: var(--accent-dim); }

.nav-right { display: flex; align-items: center; gap: 8px; }
.nav-divider { width: 1px; height: 24px; background: var(--border); margin: 0 4px; flex-shrink: 0; }

#lang-toggle {
  background: none; border: 1px solid var(--outline);
  color: var(--accent); font-family: inherit; font-size: 13.5px; font-weight: 500;
  padding: 9px 18px; border-radius: 9999px; cursor: pointer; letter-spacing: 0.1em;
  position: relative; overflow: hidden;
  display: inline-flex; align-items: center; gap: 6px;
  height: 40px; box-sizing: border-box;
  transition: background 0.2s ease, border-color 0.2s ease;
}
#lang-toggle:hover { background: var(--accent-dim); border-color: rgba(217, 119, 87, 0.5); }

/* Circular M3-style icon button (GitHub link).
 * Same height as the brand button on the left so the navbar reads as one
 * unified row. State layer on hover provides M3 feel. */
#github-btn {
  display: inline-flex; align-items: center; justify-content: center;
  width: 40px; height: 40px; border-radius: 50%;
  background: transparent; border: 1px solid var(--outline);
  color: var(--muted);
  text-decoration: none;
  cursor: pointer;
  position: relative; overflow: hidden;
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}
#github-btn:hover {
  background: var(--accent-dim);
  color: var(--accent);
  border-color: rgba(217, 119, 87, 0.5);
}
#github-btn svg { width: 18px; height: 18px; display: block; }

/* On mobile, collapse the language toggle into a circular icon button that
 * mirrors #github-btn — drop the "EN ⇄ 文" label and keep only the icon. */
@media (max-width: 767px) {
  #lang-toggle {
    width: 40px; padding: 0; gap: 0;
    justify-content: center; letter-spacing: 0;
  }
  #lang-toggle #lang-label { display: none; }
  #lang-toggle svg { width: 18px; height: 18px; }
}