.site-header {
    position: fixed;
    top: 0;
    inset-inline: 0;
    z-index: 40;
    background-color: rgba(249, 250, 251, 0.7);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid transparent;
    transition: background-color 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease, transform 0.3s ease;
}
.site-header.is-scrolled {
    background-color: rgba(255, 255, 255, 0.92);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.06);
    border-bottom-color: #f3f4f6;
}

.site-header.header-hidden {
    transform: translateY(-100%);
}

.site-header--hero {
    background-color: transparent;
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
}
.site-header--hero.is-scrolled {
    background-color: rgba(15, 23, 42, 0.75);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.15);
    border-bottom-color: rgba(255, 255, 255, 0.08);
}

.nav-link {
    color: #4b5563;
    transition: color 0.2s ease;
}
.nav-link:hover { color: #1E5631; }
.nav-link.is-active {
    color: #1E5631;
    border-bottom: 2px solid #1E5631;
    padding-bottom: 4px;
}

.menu-icon-btn { color: #374151; }

.site-header--hero:not(.is-scrolled) .nav-link { color: rgba(255, 255, 255, 0.85); }
.site-header--hero:not(.is-scrolled) .nav-link:hover { color: #fff; }
.site-header--hero:not(.is-scrolled) .nav-link.is-active { color: #C5A880; border-color: #C5A880; }
.site-header--hero:not(.is-scrolled) .menu-icon-btn { color: #fff; }
.site-header--hero:not(.is-scrolled) .theme-toggle-btn { color: rgba(255, 255, 255, 0.85); }
.site-header--hero:not(.is-scrolled) .logo-fallback-brand { color: #fff; }
.site-header--hero:not(.is-scrolled) .logo-fallback-sub { color: #C5A880; }

html.dark .site-header:not(.site-header--hero) {
    background-color: rgba(15, 23, 42, 0.7);
}
html.dark .site-header:not(.site-header--hero).is-scrolled {
    background-color: rgba(15, 23, 42, 0.92);
    border-bottom-color: #334155;
}
html.dark .nav-link { color: #94a3b8; }
html.dark .nav-link:hover { color: #C5A880; }
html.dark .nav-link.is-active { color: #C5A880; border-color: #C5A880; }
html.dark .menu-icon-btn { color: #cbd5e1; }