/* ============================================================
   HEADER.CSS
   Site header, logo and primary navigation (shared by every page).
   Mobile nav open/close is plain JS (see js/main.js), driven by
   the .open class toggled on nav.main below.
   ============================================================ */

header {
  position: sticky; top: 0; z-index: 50;
  background: var(--paper);
  border-bottom: 2px solid var(--rule-strong);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0.85rem .75rem; gap: 1rem;
}
.logo-slot { display: flex; align-items: center; text-decoration: none; }
.logo-img { width: 169px; height: 44px; display: block; }
.logo-white { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .logo-black { display: none; }
  :root:not([data-theme="light"]) .logo-white { display: block; }
}
:root[data-theme="dark"] .logo-black { display: none; }
:root[data-theme="dark"] .logo-white { display: block; }
nav.main { display: flex; align-items: center; gap: 1.7rem; }
nav.main a {
  color: var(--ink); text-decoration: none; font-weight: 600; font-size: 0.98rem;
  padding: 0.3rem 0; border-bottom: 2.5px solid transparent;
}
nav.main a:hover, nav.main a.active { border-bottom-color: var(--ink); }
nav.main a.nav-cta {
  background: var(--ink); color: var(--paper);
  padding: 0.6rem 1.25rem; border-bottom: none;
}
nav.main a.nav-cta:hover { opacity: 0.85; }
.menu-btn {
  display: none; background: none; border: 2px solid var(--ink);
  padding: 0.45rem 0.9rem; font: inherit; font-weight: 700; color: var(--ink); cursor: pointer;
}
@media (max-width: 900px) {
  .menu-btn { display: block; }
  nav.main {
    display: none; position: absolute; top: 100%; left: 0; right: 0;
    background: var(--paper); border-bottom: 2px solid var(--rule-strong);
    flex-direction: column; align-items: flex-start; gap: 0;
    padding: 0.6rem 1.4rem 1.2rem;
  }
  nav.main.open { display: flex; }
  nav.main a { padding: 0.6rem 0; width: 100%; border-bottom: 1px solid var(--rule); }
  nav.main a.nav-cta { margin-top: 0.7rem; text-align: center; border-bottom: none; }
}