:root{color-scheme:light dark;--bg-color:#f4f4f4;--text-color:#1a1a1a;--card-bg:#fff;--accent-color:#0070f3}.dark-mode{--bg-color:#0d1117;--text-color:#f0f6fc;--card-bg:#161b22;--accent-color:#58a6ff}body{background-color:var(--bg-color);color:var(--text-color);transition:background-color .3s ease,color .3s ease}.header-grid{align-items:center;display:grid;gap:2rem;grid-template-columns:auto 1fr auto;padding:1rem 0}.header-main-nav{align-items:center;display:flex;gap:2rem}.header-actions{align-items:center;display:flex;gap:1.5rem}.header-actions .btn-icon{background:none;border:1px solid rgba(var(--text-color),.2);border-radius:8px;color:var(--text-color);cursor:pointer;padding:5px 10px}.header-actions .btn-icon:hover{border-color:#0070f3}@media(max-width:768px){.header-actions{justify-content:flex-end}}.lang-switcher{align-items:center;display:flex;font-size:.85rem;font-weight:700;gap:.5rem}.lang-switcher .lang-btn{color:var(--text-color);opacity:.5;text-decoration:none;transition:opacity .2s}.lang-switcher .lang-btn.active{color:#0070f3;opacity:1}.lang-switcher .lang-btn:hover{opacity:1}.lang-switcher .separator{opacity:.3}.header-main-nav a{color:var(--text-color);text-decoration:none}.header-mobile-menu{background:var(--bg-color);box-shadow:0 6px 20px #0000001a;height:100%;left:0;padding:1rem;position:absolute;right:0;top:0;z-index:50}.header-mobile-menu .mobile-nav{display:flex;flex-direction:column;gap:1rem;margin-bottom:2rem}.header-mobile-menu a{color:var(--text-color)}.header-mobile-menu .btn-icon{margin-top:.5rem}