diff --git a/packages/app/src/context/layout.tsx b/packages/app/src/context/layout.tsx
index 2a17460fe..3c7144ed8 100644
--- a/packages/app/src/context/layout.tsx
+++ b/packages/app/src/context/layout.tsx
@@ -32,7 +32,10 @@ const DEFAULT_FILE_TREE_WIDTH = 200
 // amicode#105: single-pane Work Column — it no longer hosts the review
 // panel's two-pane split, so it doesn't need the old 400px. Resize handle
 // retained; persisted widths still override this default.
-const DEFAULT_PANEL_COLUMN_WIDTH = 320
+// Must be >= WORK_COLUMN_WIDTH_MIN (330) so the default never triggers the
+// floor in clampWorkColumnWidth, which would make the container wider than
+// the side panel's <aside> and create an asymmetric right-side gap.
+const DEFAULT_PANEL_COLUMN_WIDTH = 330
 const DEFAULT_SESSION_WIDTH = 600
 const DEFAULT_TERMINAL_HEIGHT = 280
 const DEFAULT_REVIEW_PANEL_OPENED = false
diff --git a/packages/app/src/pages/session.tsx b/packages/app/src/pages/session.tsx
index 576e36f28..b989658b0 100644
--- a/packages/app/src/pages/session.tsx
+++ b/packages/app/src/pages/session.tsx
@@ -491,7 +491,7 @@ export default function Page() {
   const sessionPanelAvailable = createMemo(() => {
     const width = panelRowWidth()
     if (width === undefined) return undefined
-    return width - (settings.general.newLayoutDesigns() ? 8 : 0)
+    return width - (settings.general.newLayoutDesigns() ? 6 : 0)
   })
   const sessionPanelMax = createMemo(() => {
     const available = sessionPanelAvailable()
@@ -2409,7 +2409,7 @@ export default function Page() {
         ref={panelRow}
         class="flex-1 min-h-0 flex flex-col md:flex-row"
         classList={{
-          "gap-2 p-2": settings.general.newLayoutDesigns(),
+           "gap-1.5 px-1.5 py-2": settings.general.newLayoutDesigns(),
         }}
       >
         <Show when={!isDesktop() && !!params.id && !settings.general.newLayoutDesigns()}>{mobileTabs()}</Show>
diff --git a/packages/app/src/pages/session/session-panel-width.test.ts b/packages/app/src/pages/session/session-panel-width.test.ts
index dca5a86c2..3fa964cd9 100644
--- a/packages/app/src/pages/session/session-panel-width.test.ts
+++ b/packages/app/src/pages/session/session-panel-width.test.ts
@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test"
 import {
   clampSessionPanelWidth,
   clampWorkColumnWidth,
+  floorPanelColumnWidth,
   REVIEW_PANE_WIDTH_MIN,
   REVIEW_PANE_WIDTH_MIN_SPLIT,
   SESSION_PANEL_WIDTH_MIN,
@@ -78,4 +79,19 @@ describe("work column width (amicode#105 — the column is bounded, the CHAT is
     expect(sessionChatTakesRemainder({ newDesign: true, columnVisible: false })).toBe(false)
     expect(sessionChatTakesRemainder({ newDesign: false, columnVisible: true })).toBe(false)
   })
+
+  test("floorPanelColumnWidth lifts a stored width below the work column minimum", () => {
+    // Regression: DEFAULT_PANEL_COLUMN_WIDTH was 320 while WORK_COLUMN_WIDTH_MIN
+    // was 330. The work column container used clampWorkColumnWidth (which floors
+    // at 330) but the side panel's <aside> used the raw stored width (320),
+    // leaving a 10px transparent gap that merged with the 8px panelRow padding
+    // for 18px of right-side gap vs only 8px on the left.
+    expect(floorPanelColumnWidth(320)).toBe(WORK_COLUMN_WIDTH_MIN)
+    expect(floorPanelColumnWidth(100)).toBe(WORK_COLUMN_WIDTH_MIN)
+  })
+
+  test("floorPanelColumnWidth passes through widths at or above the minimum", () => {
+    expect(floorPanelColumnWidth(WORK_COLUMN_WIDTH_MIN)).toBe(WORK_COLUMN_WIDTH_MIN)
+    expect(floorPanelColumnWidth(500)).toBe(500)
+  })
 })
diff --git a/packages/app/src/pages/session/session-panel-width.ts b/packages/app/src/pages/session/session-panel-width.ts
index 0c028e401..43191381a 100644
--- a/packages/app/src/pages/session/session-panel-width.ts
+++ b/packages/app/src/pages/session/session-panel-width.ts
@@ -37,6 +37,15 @@ export function clampWorkColumnWidth(input: { width: number; available: number |
   return Math.min(Math.max(input.width, WORK_COLUMN_WIDTH_MIN), workColumnWidthMax(input.available))
 }
 
+/** Floor for the side panel's own width — ensures the `<aside>` never renders
+ * narrower than its work column container (which uses `clampWorkColumnWidth`).
+ * Without this, a stored width below the column floor creates a transparent gap
+ * between the panel's right edge and the column boundary, inflating the
+ * perceived right-side padding. */
+export function floorPanelColumnWidth(width: number): number {
+  return Math.max(width, WORK_COLUMN_WIDTH_MIN)
+}
+
 /** In v2 with the work column visible, the chat is the flex remainder (no
  * fixed pixel width). Classic layout keeps the historical fixed chat width. */
 export function sessionChatTakesRemainder(input: { newDesign: boolean; columnVisible: boolean }): boolean {
diff --git a/packages/app/src/pages/session/session-side-panel.tsx b/packages/app/src/pages/session/session-side-panel.tsx
index 90e9f97ee..535f61e30 100644
--- a/packages/app/src/pages/session/session-side-panel.tsx
+++ b/packages/app/src/pages/session/session-side-panel.tsx
@@ -73,7 +73,7 @@ import {
 } from "@/pages/session/helpers"
 import { setSessionHandoff } from "@/pages/session/handoff"
 import { useSessionLayout } from "@/pages/session/session-layout"
-import { WORK_COLUMN_WIDTH_MIN } from "@/pages/session/session-panel-width"
+import { floorPanelColumnWidth, WORK_COLUMN_WIDTH_MIN } from "@/pages/session/session-panel-width"
 import { SessionFileBrowserTab, type SessionFileBrowserState } from "@/pages/session/v2/session-file-browser-tab"
 
 type PulseInspectorStage = "optimization" | "calibration" | "compilation"
@@ -325,7 +325,10 @@ export function SessionSidePanel(props: {
     if (!open()) return "0px"
     // the tabs column owns its width (never flex-fills the window) and can be
     // dragged much narrower — Kate 2026-07-27
-    if (reviewOpen()) return `${layout.panelColumn.width()}px`
+    // Floor at WORK_COLUMN_WIDTH_MIN so the <aside> always fills its work column
+    // container (which uses clampWorkColumnWidth); without this a stored width
+    // below the floor leaves a transparent gap on the right side.
+    if (reviewOpen()) return `${floorPanelColumnWidth(layout.panelColumn.width())}px`
     return `${fileTreeWidth()}px`
   })
   const treeWidth = createMemo(() => (fileOpen() ? `${fileTreeWidth()}px` : "0px"))