.app {
  display: flex;
  height: 100vh;
  overflow: hidden;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background: var(--sidebar-bg);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  transition: transform var(--transition), background-color 0.3s ease;
}

.sidebar-header {
  padding: 14px 16px;
  font-weight: 600;
  font-size: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--sidebar-text);
  border-bottom: 1px solid var(--border-color);
}

.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: 8px 4px;
}

.sidebar-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  margin: 0 4px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--sidebar-text);
  cursor: pointer;
  transition: background var(--transition);
  user-select: none;
}

.sidebar-item:hover {
  background: var(--sidebar-hover);
}

.sidebar-item.active {
  background: var(--sidebar-hover);
  font-weight: 500;
}

.sidebar-item .icon {
  font-size: 16px;
  width: 20px;
  text-align: center;
}

.sidebar-footer {
  padding: 10px 16px;
  font-size: 12px;
  color: var(--text-secondary);
  border-top: 1px solid var(--border-color);
}

/* Main */
.main {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: var(--canvas-bg);
  transition: background-color 0.3s ease;
}

.topbar {
  height: 44px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  flex-shrink: 0;
  transition: border-color 0.3s ease;
}

.topbar-left {
  display: flex;
  align-items: center;
  gap: 10px;
}

.menu-btn {
  display: none;
  padding: 6px;
  border-radius: var(--radius-sm);
  font-size: 18px;
}
.menu-btn:hover {
  background: var(--sidebar-hover);
}

.page-title {
  font-size: 14px;
  font-weight: 500;
}

.topbar-actions {
  display: flex;
  gap: 8px;
  align-items: center;
}

.btn {
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-weight: 500;
  transition: background var(--transition), color var(--transition);
}

.btn:hover {
  background: var(--sidebar-hover);
}

.btn-primary {
  background: var(--text-primary);
  color: #fff;
}
.btn-primary:hover {
  background: #000;
}

.canvas {
  flex: 1;
  overflow-y: auto;
  padding: 40px 24px 120px;
}

.canvas-inner {
  max-width: var(--canvas-max-width);
  margin: 0 auto;
}

/* Overlay for mobile sidebar */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.3);
  z-index: 90;
}

/* Responsive */
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    z-index: 100;
    transform: translateX(-100%);
  }
  .sidebar.open {
    transform: translateX(0);
  }
  .menu-btn {
    display: block;
  }
  .sidebar-overlay.show {
    display: block;
  }
  .canvas {
    padding: 20px 16px 80px;
  }
}