stretch header buttons to fill height, add gap between accessories

src/lib/components/ui/PaneStack.svelte

@@ -113,7 +113,7 @@
 					{/if}
 					{#if pane.overflowMenu && pane.overflowMenu.length > 0}
 						<DropdownMenu.Root>
-							<DropdownMenu.Trigger>
+							<DropdownMenu.Trigger class="overflow-trigger">
 								{#snippet child({ props })}
 									<Button
 										{...props}
@@ -287,6 +287,12 @@
 		}
 	}
 
+	// Overflow trigger - reset any default styles from bits-ui
+	:global(.overflow-trigger) {
+		all: unset;
+		display: flex;
+	}
+
 	// Overflow menu styles
 	:global(.overflow-menu) {
 		background: var(--menu-bg, white);

src/lib/components/ui/SidebarHeader.svelte

@@ -41,7 +41,7 @@
 		display: grid;
 		grid-template-columns: 1fr auto 1fr;
 		align-items: center;
-		padding: $unit-2x;
+		padding: $unit;
 		border-bottom: 1px solid var(--border-primary);
 		flex-shrink: 0;
 		background: var(--bg-primary);
@@ -55,6 +55,16 @@
 		.header-right {
 			display: flex;
 			align-items: center;
+
+			// Ensure all buttons in header have consistent height
+			:global([data-button-root]) {
+				height: calc($unit * 4) !important;
+
+				// Icon-only buttons should be square
+				&.iconOnly {
+					width: calc($unit * 4) !important;
+				}
+			}
 		}
 
 		.header-left {
@@ -63,6 +73,7 @@
 
 		.header-right {
 			justify-content: flex-end;
+			gap: $unit-half;
 		}
 
 		.sidebar-title {