body { margin:0; font-family:sans-serif;}
.header { display:flex; justify-content:space-between; align-items:center; height:60px; background:#fff; padding:0 16px; }
.header .left, .header .right { display:flex; align-items:center; }
.dark-theme { background:#222; color:#fff; }
.mobile-header { position:sticky; top:0; z-index:10;}