:root{
  --bg:#f7f7f7;
  --panel:#ffffff;
  --accent:#0b6;
  --muted:#666;
  --sidebar-width:240px;
}
*{box-sizing:border-box}
html,body,#app{height:100%;margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,"Helvetica Neue",Arial}
#app{display:flex;gap:0;height:100vh;background:var(--bg)}
/* Sidebar */
#sidebar{width:var(--sidebar-width);background:var(--panel);border-right:1px solid #e6e6e6;position:relative;display:flex;flex-direction:column}
#sidebar nav{padding:20px 12px;flex:1;overflow:auto}
#sidebar ul{list-style:none;padding:0;margin:0;display:grid;gap:8px}
#sidebar a{display:block;padding:10px 12px;border-radius:8px;color:#111;text-decoration:none;border:1px solid transparent}
#sidebar a:hover{background:#f0fff6;border-color:#e6f7ef}
#sidebar a:active{transform:translateY(1px)}
#toggleBtn{position:absolute;right:-34px;top:10px;width:34px;height:34px;border-radius:6px;border:1px solid #ddd;background:var(--panel);cursor:pointer;font-size:18px}
/* Main */
#main{flex:1;display:flex;flex-direction:column;height:100%}
#frameMain{flex:1;width:100%;border:0;height:100%}
#status{padding:8px 12px;background:#fff;border-top:1px solid #eee;color:var(--muted);font-size:14px}

/* Responsive: collapse sidebar on narrow screens */
@media (max-width:720px){
  #sidebar{position:absolute;left:0;top:0;bottom:0;z-index:20;transform:translateX(-100%);transition:transform .22s ease;box-shadow: 8px 0 18px rgba(0,0,0,.08)}
  #sidebar.open{transform:translateX(0)}
  #toggleBtn{right:-44px}
  #frameMain{height:100%}
}