diff --git a/packages/dashboard-ui-components/src/components/data-grid/data-grid-toolbar.tsx b/packages/dashboard-ui-components/src/components/data-grid/data-grid-toolbar.tsx
index f0ba55ed9..e3975843a 100644
--- a/packages/dashboard-ui-components/src/components/data-grid/data-grid-toolbar.tsx
+++ b/packages/dashboard-ui-components/src/components/data-grid/data-grid-toolbar.tsx
@@ -84,16 +84,16 @@ function QuickSearch({
 }) {
   return (
     <div className="relative flex min-w-0 flex-1 items-center sm:flex-initial">
-      <MagnifyingGlass className="absolute left-2.5 h-3.5 w-3.5 text-muted-foreground/50 pointer-events-none" />
+      <MagnifyingGlass className="absolute left-2.5 h-3.5 w-3.5 text-muted-foreground/60 pointer-events-none" />
       <input
         type="text"
         className={cn(
           "h-8 w-full sm:w-52 pl-8 pr-7 rounded-xl text-xs",
-          "bg-background",
-          "border border-black/[0.08] dark:border-white/[0.08]",
-          "placeholder:text-muted-foreground/40",
+          "border border-black/[0.08] dark:border-white/[0.06]",
+          "bg-white dark:bg-background shadow-sm ring-1 ring-black/[0.08] dark:ring-white/[0.06]",
+          "placeholder:text-muted-foreground/50",
           "focus:outline-none focus:ring-1 focus:ring-foreground/[0.1]",
-          "transition-all duration-150",
+          "transition-all duration-150 hover:transition-none hover:ring-black/[0.12] dark:hover:ring-white/[0.1]",
         )}
         placeholder={placeholder}
         value={value}
@@ -234,13 +234,13 @@ function ColumnManager<TRow>({
             <span className="text-[10px] font-medium uppercase tracking-wider text-muted-foreground">
               {strings.dateFormat}
             </span>
-            <div className="inline-flex items-center gap-0.5 rounded-lg bg-foreground/[0.04] p-0.5">
+            <div className="inline-flex items-center gap-0.5 rounded-lg bg-zinc-100/90 p-0.5 ring-1 ring-black/[0.06] dark:bg-foreground/[0.04] dark:ring-white/[0.06]">
               <button
                 className={cn(
-                  "px-2 py-0.5 rounded-md text-[11px] font-medium transition-colors duration-75",
+                  "px-2 py-0.5 rounded-md text-[11px] font-medium transition-colors duration-150 hover:transition-none",
                   dateDisplay === "relative"
-                    ? "bg-background text-foreground shadow-sm ring-1 ring-foreground/[0.06]"
-                    : "text-muted-foreground hover:text-foreground",
+                    ? "bg-white text-foreground shadow-sm ring-1 ring-black/[0.12] dark:bg-background dark:ring-white/[0.06]"
+                    : "text-muted-foreground hover:text-foreground hover:bg-white/50 dark:hover:bg-white/[0.06]",
                 )}
                 onClick={() => onDateDisplayChange("relative")}
               >
@@ -248,10 +248,10 @@ function ColumnManager<TRow>({
               </button>
               <button
                 className={cn(
-                  "px-2 py-0.5 rounded-md text-[11px] font-medium transition-colors duration-75",
+                  "px-2 py-0.5 rounded-md text-[11px] font-medium transition-colors duration-150 hover:transition-none",
                   dateDisplay === "absolute"
-                    ? "bg-background text-foreground shadow-sm ring-1 ring-foreground/[0.06]"
-                    : "text-muted-foreground hover:text-foreground",
+                    ? "bg-white text-foreground shadow-sm ring-1 ring-black/[0.12] dark:bg-background dark:ring-white/[0.06]"
+                    : "text-muted-foreground hover:text-foreground hover:bg-white/50 dark:hover:bg-white/[0.06]",
                 )}
                 onClick={() => onDateDisplayChange("absolute")}
               >
diff --git a/packages/dashboard-ui-components/src/components/data-grid/data-grid.test.tsx b/packages/dashboard-ui-components/src/components/data-grid/data-grid.test.tsx
index f973ef70f..308355a3c 100644
--- a/packages/dashboard-ui-components/src/components/data-grid/data-grid.test.tsx
+++ b/packages/dashboard-ui-components/src/components/data-grid/data-grid.test.tsx
@@ -101,8 +101,43 @@ class MockIntersectionObserver implements IntersectionObserver {
 }
 
 class MockResizeObserver implements ResizeObserver {
+  private readonly callback: ResizeObserverCallback;
+
+  constructor(callback: ResizeObserverCallback) {
+    this.callback = callback;
+  }
+
   disconnect() {}
-  observe() {}
+  observe(target: Element) {
+    const el = target instanceof HTMLElement ? target : null;
+    const parentWidth = el?.parentElement instanceof HTMLElement ? el.parentElement.clientWidth : 0;
+    const width = (el?.clientWidth ?? 0) > 0 ? (el?.clientWidth ?? 320) : parentWidth > 0 ? parentWidth : 320;
+    const height = (el?.clientHeight ?? 0) > 0 ? (el?.clientHeight ?? 400) : 400;
+    this.callback(
+      [
+        {
+          target,
+          contentRect: {
+            x: 0,
+            y: 0,
+            width,
+            height,
+            top: 0,
+            left: 0,
+            right: width,
+            bottom: height,
+            toJSON() {
+              return this;
+            },
+          } as DOMRectReadOnly,
+          borderBoxSize: [],
+          contentBoxSize: [],
+          devicePixelContentBoxSize: [],
+        },
+      ],
+      this,
+    );
+  }
   unobserve() {}
 }
 
@@ -307,6 +342,12 @@ describe("DataGrid controlled callbacks", () => {
 describe("DataGrid horizontal scrolling", () => {
   beforeEach(() => {
     vi.stubGlobal("ResizeObserver", MockResizeObserver);
+    Object.defineProperty(HTMLElement.prototype, "clientWidth", {
+      configurable: true,
+      get() {
+        return 320;
+      },
+    });
     vi.spyOn(HTMLElement.prototype, "getBoundingClientRect").mockImplementation(
       function getBoundingClientRect() {
         return {
@@ -344,13 +385,17 @@ describe("DataGrid horizontal scrolling", () => {
     vi.unstubAllGlobals();
   });
 
-  it("sizes the sticky clipping layer to the full row width", () => {
+  it("does not keep the full unscaled column width in a narrow container", async () => {
     const { container } = render(<WideDataGridHarness />);
 
     const rowsClip = container.querySelector("[data-data-grid-rows-clip]");
 
     expect(rowsClip).toBeInstanceOf(HTMLElement);
-    expect((rowsClip as HTMLElement).style.minWidth).toBe("740px");
+    await waitFor(() => {
+      const widthPx = Number.parseInt((rowsClip as HTMLElement).style.minWidth, 10);
+      expect(widthPx).toBeLessThan(740);
+      expect(widthPx).toBeLessThanOrEqual(320);
+    });
   });
 
   it("lets the columns popover escape the sticky toolbar bounds", () => {
diff --git a/packages/dashboard-ui-components/src/components/data-grid/data-grid.tsx b/packages/dashboard-ui-components/src/components/data-grid/data-grid.tsx
index 6dc55f9de..54ec58383 100644
--- a/packages/dashboard-ui-components/src/components/data-grid/data-grid.tsx
+++ b/packages/dashboard-ui-components/src/components/data-grid/data-grid.tsx
@@ -36,7 +36,7 @@ import React, {
 } from "react";
 
 import { DesignSkeleton } from "../skeleton";
-import { DEFAULT_COL_WIDTH, clampColumnWidth, getEffectiveMaxWidth, getEffectiveMinWidth } from "./data-grid-sizing";
+import { DEFAULT_COL_WIDTH, clampColumnWidth, fitColumnsToContainer, getEffectiveMaxWidth, getEffectiveMinWidth } from "./data-grid-sizing";
 import { DataGridToolbar } from "./data-grid-toolbar";
 import { exportToCsv, formatGridDate, resolveColumnValue } from "./state";
 import { resolveDataGridStrings } from "./strings";
@@ -104,29 +104,6 @@ function resolveUpdater<T>(updater: Updater<T>, current: T): T {
   return typeof updater === "function" ? (updater as (old: T) => T)(current) : updater;
 }
 
-// ─── Flex column width distribution ──────────────────────────────────
-
-function distributeFlexWidths<TRow>(
-  sizes: Record<string, number>,
-  visibleColumns: readonly DataGridColumnDef<TRow>[],
-  available: number,
-): void {
-  const flexCols = visibleColumns.filter((c) => c.flex != null && c.flex > 0);
-  if (flexCols.length === 0 || available <= 0) return;
-  const totalFlex = flexCols.reduce((acc, c) => acc + (c.flex ?? 0), 0);
-  let remaining = available;
-  flexCols.forEach((col, i) => {
-    const isLast = i === flexCols.length - 1;
-    const share = isLast
-      ? remaining
-      : Math.floor(available * ((col.flex ?? 0) / totalFlex));
-    const max = col.maxWidth ?? Infinity;
-    const add = Math.max(0, Math.min(share, max - sizes[col.id]));
-    sizes[col.id] += add;
-    remaining -= add;
-  });
-}
-
 // ─── Selection logic (with shift-range anchor) ───────────────────────
 
 type SelectionInput = {
@@ -512,9 +489,10 @@ function DefaultFooter<TRow>({
             <span>{strings.rowsPerPage}</span>
             <select
               className={cn(
-                "h-7 rounded-lg border border-black/[0.08] dark:border-white/[0.08] bg-background px-1.5",
+                "h-7 rounded-lg border border-black/[0.08] dark:border-white/[0.06] px-1.5",
+                "bg-white dark:bg-background shadow-sm ring-1 ring-black/[0.08] dark:ring-white/[0.06]",
                 "text-xs text-foreground focus:outline-none focus:ring-1 focus:ring-foreground/[0.1]",
-                "cursor-pointer",
+                "cursor-pointer transition-all duration-150 hover:transition-none hover:ring-black/[0.12] dark:hover:ring-white/[0.1]",
               )}
               value={state.pagination.pageSize}
               onChange={(e) => setPageSize(Number(e.target.value))}
@@ -798,12 +776,22 @@ export function DataGrid<TRow>(props: DataGridProps<TRow>) {
     const grid = gridRef.current;
     const scroller = scrollContainerRef.current;
     if (!grid) return;
-    const update = () => {
-      const w = scroller?.clientWidth ?? grid.clientWidth;
-      if (w > 0) setContainerWidth(w);
+    const update = (entries?: ResizeObserverEntry[]) => {
+      let measured = 0;
+      if (entries != null) {
+        for (const entry of entries) {
+          measured = Math.max(measured, entry.contentRect.width);
+        }
+      }
+      if (measured <= 0) {
+        const scrollerWidth = scroller?.clientWidth ?? 0;
+        const gridWidth = grid.clientWidth;
+        measured = scrollerWidth > 0 ? scrollerWidth : gridWidth;
+      }
+      if (measured > 0) setContainerWidth(measured);
     };
     update();
-    const observer = new ResizeObserver(update);
+    const observer = new ResizeObserver((entries) => update(entries));
     observer.observe(grid);
     if (scroller) observer.observe(scroller);
     return () => observer.disconnect();
@@ -814,7 +802,7 @@ export function DataGrid<TRow>(props: DataGridProps<TRow>) {
   const columnSizingInfo = table.getState().columnSizingInfo;
   const columnSizes = useMemo<Record<string, number>>(() => {
     const sizes: Record<string, number> = {};
-    let baseTotal = selectionMode !== "none" ? 44 : 0;
+    const selectionChromeWidth = selectionMode !== "none" ? 44 : 0;
     const resizingId = columnSizingInfo.isResizingColumn || null;
     const deltaOffset = columnSizingInfo.deltaOffset ?? 0;
     for (const col of visibleColumns) {
@@ -824,9 +812,8 @@ export function DataGrid<TRow>(props: DataGridProps<TRow>) {
         ? clampColumnWidth(col, baseSize + deltaOffset)
         : baseSize;
       sizes[col.id] = liveSize;
-      baseTotal += liveSize;
     }
-    distributeFlexWidths(sizes, visibleColumns, containerWidth - baseTotal);
+    fitColumnsToContainer(sizes, visibleColumns, containerWidth, selectionChromeWidth);
     return sizes;
   }, [visibleColumns, table, columnSizingInfo, state.columnWidths, containerWidth, selectionMode]);