diff --git a/gui/src/styles-compatibility-matrix.css b/gui/src/styles-compatibility-matrix.css
index db86e4a89d..38ff9f61f9 100644
--- a/gui/src/styles-compatibility-matrix.css
+++ b/gui/src/styles-compatibility-matrix.css
@@ -3,7 +3,16 @@
    Namespace: lab-matrix-
    ============================================================================ */
 
-.main-inner:has(.lab-page) {
+/*
+  Scoped to the VISIBLE compatibility panel by id, not to `.lab-page`: the lab renders no
+  `.lab-page` while it is loading (skeleton), so a `:has(.lab-page)` test dropped the width
+  to 980px during load and snapped to 1200px afterwards — the tab's size was not fixed. It
+  also matched from any tab once the lab had been opened (panels stay mounted), leaking the
+  width across tabs. `#models-panel-compatibility:not([hidden])` is true only while this is
+  the active tab, so the width is held steady across load/error and never leaks. Matches the
+  catalog and routing rules in styles-models-workspace.css.
+*/
+.main-inner:has(#models-panel-compatibility:not([hidden])) {
   max-width: 1200px;
   box-sizing: border-box;
 }
diff --git a/gui/src/styles-models-workspace.css b/gui/src/styles-models-workspace.css
index ab00d41402..e1120eb04c 100644
--- a/gui/src/styles-models-workspace.css
+++ b/gui/src/styles-models-workspace.css
@@ -8,14 +8,29 @@
 /*
   The catalog wants a wider column than the 980px default.
 
-  Scoped to a VISIBLE catalog panel, not merely a present one: panels mount lazily and
-  then stay mounted so drafts survive a tab hop, so a bare `:has(.models-workspace-shell)`
-  keeps matching after the catalog has been opened once. Routing would then render at
-  980px on a direct visit and 1200px afterwards — a width that depends on browsing
-  history. No surface renders the shell outside a tabpanel any more, so the old
-  direct-child arm is gone with the standalone pages it served.
+  Scoped to the VISIBLE catalog panel by its id: `#models-panel-catalog:not([hidden])` is
+  true only while catalog is the active tab (an inactive panel carries `hidden`), so this
+  never leaks onto another tab even though panels stay mounted after their first visit.
+
+  It deliberately does NOT also require `.models-workspace-shell`: the shell is absent
+  while the catalog is loading (skeleton) or after a cold failure (error notice), so gating
+  on it dropped the width back to 980px in those states and snapped it to 1200px only once
+  data arrived — the catalog tab's size was not fixed. The panel-id test alone holds the
+  width steady across load, empty, and error, matching the routing rule below.
 */
-.main-inner:has(#models-panel-catalog:not([hidden]) .models-workspace-shell) {
+.main-inner:has(#models-panel-catalog:not([hidden])) {
+  max-width: 1200px;
+}
+
+/*
+  Routing shares the catalog/compatibility 1200px column so hopping between the Models
+  tabs never resizes the page. Scoped to the VISIBLE routing panel for the same reason
+  the catalog rule is: panels stay mounted after their first visit, so an unscoped `:has`
+  would leak this width onto whatever tab is open. Without this rule routing fell back to
+  the 980px `.main-inner` default — a visible width jump on every hop to it, and one that
+  only appeared once the compatibility tab's own `:has(.lab-page)` had leaked 1200px in.
+*/
+.main-inner:has(#models-panel-routing:not([hidden])) {
   max-width: 1200px;
 }
 
diff --git a/gui/src/styles.css b/gui/src/styles.css
index 1d321fc843..d7b98bbbef 100644
--- a/gui/src/styles.css
+++ b/gui/src/styles.css
@@ -450,6 +450,46 @@ input[type="checkbox"], input[type="radio"] { accent-color: var(--accent); }
 }
 .main-inner.main-inner--combos > .page-sub { margin-bottom: 10px; }
 
+/* Keep the Models tab strip border aligned with its tab buttons in the full-bleed layout. */
+.main-inner.main-inner--combos > .page-tabs {
+  margin-inline: 36px;
+  padding-inline: 0;
+}
+
+/*
+  Full-bleed is for the combos WORKSPACE grid only. Its loading and error fallbacks render
+  no `.combos-workspace-shell` (Combos.tsx returns a bare skeleton or an error notice), yet
+  `main-inner--combos` is applied on tab selection alone — so with no workspace to fill, the
+  lone subtitle/notice/retry stretched edge to edge (padding:0, max-width:none, flex column)
+  while every sibling Models tab stayed boxed. That is the "콤보만 영역이 이상해짐" report.
+
+  When no workspace shell is present, drop the full-bleed and box the page like the other
+  tabs: reset the container, its chrome inset, and the fill panel back to normal flow.
+*/
+/*
+  Each rule below is a SINGLE selector on purpose. Vite's Rolldown CSS minifier corrupts a
+  comma-separated selector list whose selectors carry `:not(:has(...))` — it emits a stray
+  `)` before the block and the browser then drops the whole rule. A single `:not(:has())`
+  selector minifies correctly, so the chrome inset is handled without a list: the container
+  drops its own horizontal padding and the page chrome keeps the 36px inline padding it
+  already gets above (`.main-inner--combos > .page-head` etc.), which the panel matches.
+*/
+.main-inner.main-inner--combos:not(:has(.combos-workspace-shell)) {
+  max-width: 1200px;
+  margin: 0 auto;
+  padding: 32px 0 64px;
+  min-height: 0;
+  height: auto;
+  overflow: visible;
+  display: block;
+}
+.main-inner.main-inner--combos:not(:has(.combos-workspace-shell)) > .models-tab-panel--fill:not([hidden]) {
+  flex: 0 1 auto;
+  height: auto;
+  display: block;
+  padding-inline: 36px;
+}
+
 /* ---- page header ---- */
 .page-head { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-bottom: 6px; }
 .page-head h2 { font-size: var(--text-title); }
diff --git a/gui/tests/models-tab-layout.test.ts b/gui/tests/models-tab-layout.test.ts
new file mode 100644
index 0000000000..f1d203dc41
--- /dev/null
+++ b/gui/tests/models-tab-layout.test.ts
@@ -0,0 +1,51 @@
+import { expect, test } from "bun:test";
+import { effectiveDeclaration, withoutComments } from "./helpers/css-declarations";
+
+async function readStylesheet(path: string): Promise<string> {
+  return withoutComments(await Bun.file(new URL(path, import.meta.url)).text());
+}
+
+test("Models tab strips keep their full-bleed container borders aligned", async () => {
+  const baseStyles = await readStylesheet("../src/styles.css");
+  const workspaceStyles = await readStylesheet("../src/styles-models-workspace.css");
+  const compatibilityStyles = await readStylesheet("../src/styles-compatibility-matrix.css");
+
+  // The Combos workspace removes the outer container padding. Replacing the tab strip's
+  // padding with an equal inline margin keeps its border aligned with the tab buttons.
+  expect(effectiveDeclaration(
+    baseStyles,
+    ".main-inner.main-inner--combos > .page-tabs",
+    "margin-inline",
+  )).toBe("36px");
+  expect(effectiveDeclaration(
+    baseStyles,
+    ".main-inner.main-inner--combos > .page-tabs",
+    "padding-inline",
+  )).toBe("0");
+
+  // Loading, empty, and error fallbacks do not render the workspace shell. Keep those
+  // shell-free states boxed instead of allowing the full-bleed Combos container to stretch
+  // their notice and retry controls edge to edge.
+  const shellFreeContainer = ".main-inner.main-inner--combos:not(:has(.combos-workspace-shell))";
+  expect(effectiveDeclaration(baseStyles, shellFreeContainer, "max-width")).toBe("1200px");
+  expect(effectiveDeclaration(baseStyles, shellFreeContainer, "margin")).toBe("0 auto");
+  expect(effectiveDeclaration(baseStyles, shellFreeContainer, "padding")).toBe("32px 0 64px");
+
+  const shellFreePanel = `${shellFreeContainer} > .models-tab-panel--fill:not([hidden])`;
+  expect(effectiveDeclaration(baseStyles, shellFreePanel, "display")).toBe("block");
+  expect(effectiveDeclaration(baseStyles, shellFreePanel, "padding-inline")).toBe("36px");
+
+  // Every Models workspace tab uses the same column width, including loading/error states
+  // where the panel content itself may not have mounted yet.
+  for (const selector of [
+    ".main-inner:has(#models-panel-catalog:not([hidden]))",
+    ".main-inner:has(#models-panel-routing:not([hidden]))",
+  ]) {
+    expect(effectiveDeclaration(workspaceStyles, selector, "max-width")).toBe("1200px");
+  }
+  expect(effectiveDeclaration(
+    compatibilityStyles,
+    ".main-inner:has(#models-panel-compatibility:not([hidden]))",
+    "max-width",
+  )).toBe("1200px");
+});