body, html {
  margin: 0;
  height: 100%;
  width: 100%;
  overflow: hidden;
  font-family: Arial, sans-serif;
}

/* Root container */
#app-shell {
  display: flex;
  flex-direction: column;
  height: 100vh;
  width: 100%;
  position: relative;
}

/* Header */
#shell-header {
  height: 50px;
  background: #111;
  color: white;
  display: flex;
  align-items: center;
  padding: 0 16px;
  justify-content: space-between;
}

/* Toggle button */
#menu-toggle {
  background: #333;
  color: white;
  border: none;
  padding: 6px 10px;
  cursor: pointer;
  border-radius: 4px;
}

/* =========================
   MENU (OPTIMIZED)
   ========================= */
#shell-menu {
  position: absolute;
  top: 50px;
  left: 0;
  width: 100%;

  /* 🔥 GPU + no layout shift */
  transform: translate3d(0, -10px, 0);
  opacity: 0;
  visibility: hidden;

  background: #fafafa;
  z-index: 1000;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);

  /* 🔥 faster + smoother */
  transition: transform 0.15s ease-out, opacity 0.12s linear;

  /* 🔥 isolate from Plotly + Dash */
  will-change: transform, opacity;
}

/* OPEN STATE */
#shell-menu.open {
  transform: translate3d(0, 0, 0);
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

/* ❌ REMOVED heavy backdrop (was causing repaint lag) */

/* =========================
   CONTROLS
   ========================= */
#shell-controls {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 10px;
}

/* Allow dropdowns (KPI panel) to escape */
#shell-controls * {
  overflow: visible !important;
}

/* Control sections (your wrapper) */
.control-block {
  background: white;
  border: 1px solid #ddd;
  border-radius: 6px;
  padding: 8px;
}

/* =========================
   GRAPH AREA
   ========================= */
#shell-render {
  flex: 1;
  width: 100%;
  height: 100%;
  position: relative;
  overflow: hidden;

  /* 🔥 isolate Plotly rendering */
  transform: translateZ(0);
}