.site-header{position:sticky;top:0;z-index:var(--ac-z-header);background:var(--ac-glass-bg-strong);backdrop-filter:blur(var(--ac-glass-blur-sm)) saturate(160%);-webkit-backdrop-filter:blur(var(--ac-glass-blur-sm)) saturate(160%);border-bottom:1px solid var(--ac-glass-border);height:var(--ac-header-height);transition:height .25s var(--ac-ease,ease),box-shadow .25s ease,background .25s ease}.site-header.is-sticky{height:var(--ac-header-height-sticky);box-shadow:var(--ac-shadow-soft)}.theme-toggle-btn{width:40px;height:40px;border-radius:50%;display:flex;align-items:center;justify-content:center;transition:transform var(--ac-transition),background var(--ac-transition)}.theme-toggle-btn:hover{transform:rotate(20deg);background:var(--ac-bg-alt)}[data-theme="dark"] .theme-toggle-btn .icon-sun{display:inline}[data-theme="dark"] .theme-toggle-btn .icon-moon{display:none}.theme-toggle-btn .icon-sun{display:none}.theme-toggle-btn .icon-moon{display:inline}.site-header .container{height:100%;display:flex;align-items:center;justify-content:space-between;gap:var(--ac-space-md)}.site-logo img{height:40px;width:auto}.header-actions{display:flex;align-items:center;gap:10px}.lang-switcher{position:relative}.lang-switcher button{display:flex;align-items:center;gap:6px;font-size:var(--ac-small);font-weight:600;padding:8px 10px;border-radius:var(--ac-radius-sm)}.lang-switcher button:hover{background:var(--ac-bg-alt)}.lang-dropdown{position:absolute;right:0;top:110%;background:var(--ac-white);border:1px solid var(--ac-border);border-radius:var(--ac-radius-sm);box-shadow:var(--ac-shadow-md);min-width:140px;display:none;overflow:hidden}.lang-switcher:hover .lang-dropdown,.lang-switcher:focus-within .lang-dropdown{display:block}.lang-dropdown a{display:block;padding:10px 14px;font-size:var(--ac-small)}.lang-dropdown a:hover{background:var(--ac-bg-alt)}.lang-dropdown a.is-active{background:var(--ac-bg-alt);color:var(--ac-primary);font-weight:600}.menu-toggle{display:none}