/* Shared shell: the header and the always-open sidebar that index.html got with v3.
   Prefixed sh- so it cannot collide with the older ../assets/style.css each inner
   page still uses for its own content. */
:root { --sh-bg: #ffffff; --sh-bg2: #f6f7f9; --sh-line: #e5e7eb; --sh-fg: #0f172a; --sh-body: #334155;
  --sh-dim: #64748b; --sh-accent: #2563eb; }
@media (prefers-color-scheme: dark) {
  :root { --sh-bg: #0b0f17; --sh-bg2: #111722; --sh-line: #232b3a; --sh-fg: #f1f5f9; --sh-body: #cbd5e1;
    --sh-dim: #8b95a7; --sh-accent: #4a9eff; }
}
.sh-top { border-bottom: 1px solid var(--sh-line); background: var(--sh-bg); }
.sh-top .sh-inner { max-width: 1040px; margin: 0 auto; padding: 0 22px; display: flex; align-items: center;
  justify-content: space-between; height: 58px; gap: 16px; }
.sh-brand { display: flex; align-items: center; gap: 10px; color: var(--sh-fg); font-weight: 600;
  font-size: 15px; text-decoration: none; }
.sh-brand img { width: 28px; height: 28px; border-radius: 7px; }
.sh-cta { border: 1px solid var(--sh-accent); background: var(--sh-accent); color: #fff; border-radius: 9px;
  padding: 7px 13px; font-size: 14px; font-weight: 600; text-decoration: none; white-space: nowrap; }
.sh-rail { position: fixed; top: 0; left: 0; bottom: 0; width: 216px; overflow-y: auto; z-index: 20;
  background: var(--sh-bg2); border-right: 1px solid var(--sh-line); padding: 16px 18px 26px; }
.sh-rail h4 { margin: 18px 0 6px; font-size: 11px; letter-spacing: .08em; text-transform: uppercase;
  color: var(--sh-dim); }
.sh-rail h4:first-child { margin-top: 0; }
.sh-rail a { display: block; padding: 7px 0; color: var(--sh-body); font-size: 14.5px;
  border-bottom: 1px solid var(--sh-line); text-decoration: none; }
.sh-rail a:hover { color: var(--sh-accent); }
.sh-rail .sh-cta { display: block; margin-top: 18px; text-align: center; border-bottom: 0; }
@media (min-width: 1000px) { body { padding-left: 216px; } }
@media (max-width: 999px) {
  .sh-rail { position: static; width: auto; height: auto; border-right: 0; border-bottom: 1px solid var(--sh-line); }
}

/* ── The rail collapses behind a Menu button on phones ────────────────────────
   Added 2026-09-06. Above 1000px nothing changes — the rail stays open, always,
   which is what he asked for on desktop. Markup comes from assets/rail-menu.js. */
.rail-toggle { display: none; }
@media (max-width: 999px) {
  .rail-toggle { display: flex; align-items: center; gap: 10px; width: 100%;
    padding: 12px 22px; font: inherit; font-size: 15px; font-weight: 600;
    color: var(--sh-fg, #0f172a); background: var(--sh-bg2, #f6f7f9);
    border: 0; border-bottom: 1px solid var(--sh-line, #e5e7eb); cursor: pointer; }
  .rail-bars { display: inline-block; width: 18px; height: 2px; position: relative;
    background: currentColor; box-shadow: 0 -6px 0 currentColor, 0 6px 0 currentColor; }
  .sh-rail, .rail { display: none; }
  .sh-rail.rail-open, .rail.rail-open { display: block; }
}