diff --git a/frontend/src/components/ArticleReader.jsx b/frontend/src/components/ArticleReader.jsx
index 16cfee5..0aef7d6 100644
--- a/frontend/src/components/ArticleReader.jsx
+++ b/frontend/src/components/ArticleReader.jsx
@@ -309,16 +309,15 @@ export default function ArticleReader({
     <div className={`article-layout${railOpen ? '' : ' is-railed-off'}${aside ? ' has-aside' : ''}`}
       ref={root} style={{ '--article-top': `${headerTop}px` }}>
       <aside id={`${idPrefix}article-sections`} className={`article-sections ${drawerOpen ? 'open' : ''}`}>
+        {/* Outside the scroller, because it hangs over the boundary between the
+            rail and the prose — which is where the reader is looking when they
+            decide they want the width, and inside it would be clipped. */}
+        <button type="button" className="article-rail-hide" aria-expanded={railOpen}
+          aria-label="Collapse contents" onClick={() => setRailOpen(false)}>
+          <span aria-hidden="true">‹</span>
+        </button>
         <div className="article-rail-scroll">
-          <div className="article-rail-head">
-            <h4>{article.title}</h4>
-            {/* On the boundary between the rail and the prose, which is where
-                the reader is looking when they decide they want the width. */}
-            <button type="button" className="article-rail-hide" aria-expanded={railOpen}
-              aria-label="Collapse contents" onClick={() => setRailOpen(false)}>
-              <span aria-hidden="true">‹</span>
-            </button>
-          </div>
+          <h4>{article.title}</h4>
           {/* A contents list of one entry is not a contents list. */}
           {!soleSection && (
           <ul className="atoc">
@@ -364,7 +363,7 @@ export default function ArticleReader({
                 and a control with twelve answers to that is a control you
                 have to think about mid-paragraph. */}
             <button type="button" className="article-tool"
-              aria-label={`Text size: ${{ s: 'small', m: 'medium', l: 'large' }[size]}`}
+              aria-label={`Change text size — currently ${{ s: 'small', m: 'medium', l: 'large' }[size]}`}
               onClick={() => setSize(SIZES[(SIZES.indexOf(size) + 1) % SIZES.length])}>
               <span aria-hidden="true">A</span><span aria-hidden="true" className="article-tool-a">a</span>
             </button>
diff --git a/frontend/src/components/ArticleSaveButton.test.jsx b/frontend/src/components/ArticleSaveButton.test.jsx
new file mode 100644
index 0000000..0bb2348
--- /dev/null
+++ b/frontend/src/components/ArticleSaveButton.test.jsx
@@ -0,0 +1,56 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { render, screen, waitFor, within } from '@testing-library/react'
+import userEvent from '@testing-library/user-event'
+import ArticleSaveButton from './ArticleSaveButton'
+import api from '../api/client'
+
+vi.mock('../api/client', () => ({ default: { get: vi.fn(), post: vi.fn(), put: vi.fn() } }))
+
+const libraries = [{ id: 4, title: 'Neurology' }, { id: 9, title: 'Airway' }]
+
+describe('keeping a topic', () => {
+  beforeEach(() => {
+    vi.resetAllMocks()
+    localStorage.clear()
+    api.get.mockResolvedValue({ data: libraries })
+  })
+
+  it('files the topic’s questions into a library and says so afterwards', async () => {
+    api.put.mockResolvedValue({ data: {} })
+    render(<ArticleSaveButton articleId={1} questionIds={[11, 12]} />)
+
+    await userEvent.click(screen.getByRole('button', { name: 'Save this topic to a library' }))
+    const panel = await screen.findByRole('dialog', { name: /Save this topic/ })
+    await userEvent.click(within(panel).getByRole('button', { name: /Neurology/ }))
+
+    await waitFor(() => expect(api.put).toHaveBeenCalledWith('/collections/4/questions/11'))
+    expect(api.put).toHaveBeenCalledWith('/collections/4/questions/12')
+    // A reader should be able to tell at a glance that this one is already put
+    // away, without opening the panel to find out.
+    expect(await screen.findByRole('button', { name: 'Saved to 1 library' })).toBeInTheDocument()
+  })
+
+  it('names a new library and files into it in one press', async () => {
+    api.post.mockResolvedValue({ data: { id: 21, title: 'Seizures' } })
+    api.put.mockResolvedValue({ data: {} })
+    render(<ArticleSaveButton articleId={1} questionIds={[11]} />)
+
+    await userEvent.click(screen.getByRole('button', { name: 'Save this topic to a library' }))
+    await screen.findByRole('dialog', { name: /Save this topic/ })
+    await userEvent.type(screen.getByLabelText('Create or find a library'), 'Seizures')
+    await userEvent.click(screen.getByRole('button', { name: /Seizures/ }))
+
+    await waitFor(() => expect(api.post).toHaveBeenCalledWith('/collections/', { title: 'Seizures' }))
+    expect(api.put).toHaveBeenCalledWith('/collections/21/questions/11')
+  })
+
+  // A library holds questions. Offering the control anyway would file nothing
+  // and say nothing about why.
+  it('says plainly when a topic has no questions to file', async () => {
+    render(<ArticleSaveButton articleId={1} questionIds={[]} />)
+    await userEvent.click(screen.getByRole('button', { name: 'Save this topic to a library' }))
+
+    expect(await screen.findByText(/No questions are linked to this topic yet/)).toBeInTheDocument()
+    expect(screen.queryByLabelText('Create or find a library')).toBeNull()
+  })
+})
diff --git a/frontend/src/components/ArticleSplitPane.css b/frontend/src/components/ArticleSplitPane.css
index 585a2fa..9100b90 100644
--- a/frontend/src/components/ArticleSplitPane.css
+++ b/frontend/src/components/ArticleSplitPane.css
@@ -1,89 +1,101 @@
-/* Split view: a cross-reference read beside the article that pointed at it. */
+/* Split view: a cross-reference read beside the article that pointed at it.
 
-.article-split { min-width: 0; }
-.article-split.is-open {
-  display: grid;
-  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
-  gap: 16px;
-  align-items: start;
-}
-/* Two columns of prose need more room than one. At the reading page's usual
-   1080px each pane would be narrower than a table. */
-.article-page.is-split { max-width: min(1560px, 100%); }
+   A third column of the reading grid, at a width that never changes. The pane
+   used to be a nested page — a whole reader, contents rail and all, inside a
+   box half the width of the screen — and the article kept shuffling right as
+   you followed one reference after another. A fixed column and a rail-less
+   reader mean the prose on the left reflows once, when the pane opens, and
+   stays exactly where it is however deep the trail goes. */
 
-/* Each pane scrolls alone, which is the whole point: following a
-   cross-reference must not move the article you were reading. */
-.article-split.is-open > .article-split-main,
-.article-split.is-open > .article-split-pane {
-  max-height: calc(100dvh - 120px);
-  overflow-y: auto;
+.article-layout.has-aside {
+  grid-template-columns: 272px minmax(0, 1fr) clamp(340px, 30vw, 520px);
+}
+.article-layout.has-aside.is-railed-off {
+  grid-template-columns: 30px minmax(0, 1fr) clamp(340px, 30vw, 520px);
 }
-/* The rail is sticky inside its own pane now, not inside the window. */
-.article-page.is-split .article-sections { top: 6px; max-height: calc(100dvh - 200px); }
-.article-page.is-split .article-layout { grid-template-columns: 190px 1fr; gap: 14px; }
-.article-page.is-split .article-content { padding: 16px 18px; }
 
 .article-split-pane {
+  position: sticky;
+  top: var(--article-top);
+  display: flex;
+  flex-direction: column;
+  /* Its own scroll, which is the whole point: following a cross-reference must
+     not move the article you were reading. */
+  max-height: calc(100dvh - var(--article-top));
   background: var(--card-bg);
-  border: 1px solid var(--border);
-  border-radius: var(--card-radius);
+  border-left: 1px solid var(--border);
 }
-.article-split-pane:focus-visible { outline: 2px solid var(--primary); outline-offset: 2px; }
+.article-split-pane:focus-visible { outline: 2px solid var(--primary); outline-offset: -2px; }
 
 .asplit-head {
-  position: sticky;
-  top: 0;
-  z-index: 2;
   display: flex;
   align-items: center;
-  gap: 10px;
+  gap: 8px;
+  flex: none;
   padding: 10px 12px;
-  background: var(--card-bg);
+  background: var(--bg);
   border-bottom: 1px solid var(--border);
-  border-radius: var(--card-radius) var(--card-radius) 0 0;
 }
 .asplit-title {
   flex: 1;
   min-width: 0;
-  font-size: 0.95rem;
+  font-size: 0.92rem;
   font-weight: 700;
   color: var(--text);
   text-decoration: none;
   overflow-wrap: anywhere;
 }
 .asplit-title:hover { color: var(--primary); }
-.asplit-close {
+.asplit-back, .asplit-close {
   flex-shrink: 0;
-  width: 30px;
-  height: 30px;
+  width: 28px;
+  height: 28px;
   background: none;
   border: 1px solid var(--border);
   border-radius: 8px;
   font: inherit;
+  line-height: 1;
   color: var(--text-muted);
   cursor: pointer;
 }
-.asplit-close:hover { border-color: var(--primary); color: var(--primary); }
-.asplit-body { padding: 4px 12px 16px; }
-/* The pane is already a card, so the reader inside it does not draw a second one. */
-.asplit-body .article-content { background: none; border: 0; padding: 8px 0 0; }
+.asplit-back:hover, .asplit-close:hover { border-color: var(--primary); color: var(--primary); }
+.asplit-body { flex: 1; min-height: 0; overflow-y: auto; padding: 12px 16px 24px; }
+/* Prose, not a page: no rail, no controls, sections already open. */
+.article-bare { font-size: 0.92rem; line-height: 1.6; }
+.article-bare > .rich-text + .rich-text { margin-top: 0.7em; }
+.article-bare .article-summary {
+  color: var(--text-muted);
+  border-left: 3px solid var(--primary);
+  padding-left: 10px;
+  margin: 0 0 12px;
+}
+.article-bare .asec { border-bottom: 0; }
+.article-bare .asec-heading { margin: 14px 0 2px; }
+.article-bare .asec-head { min-height: 0; padding: 2px 0; font-size: 0.95rem; cursor: default; }
+.article-bare .asec-head:hover { background: none; }
+.article-bare .asec-chevron { display: none; }
+.article-bare .asec-body { padding: 0; font-size: 1em; }
+
+@media (max-width: 1200px) {
+  /* Three columns are tight here. The rail gives up what it can spare rather
+     than disappearing on its own — hiding it would leave the reader with no
+     handle to bring it back, since the chevron goes with it. */
+  .article-layout.has-aside { grid-template-columns: 190px minmax(0, 1fr) clamp(300px, 32vw, 420px); }
+  .article-layout.has-aside.is-railed-off { grid-template-columns: 30px minmax(0, 1fr) clamp(300px, 32vw, 420px); }
+}
 
 @media (max-width: 820px) {
   /* Two panes on a phone are two unreadable columns, and shrinking one to a
      strip only invites pinch-zoom. The cross-reference takes the screen
      instead, as a sheet over the article — which is still exactly where it was,
      at the same scroll position, when the sheet closes. */
-  .article-split.is-open { display: block; }
-  .article-split.is-open > .article-split-main { max-height: none; overflow: visible; }
-  .article-page.is-split { max-width: 1080px; }
-  .article-page.is-split .article-layout { grid-template-columns: 1fr; }
-  .article-split.is-open > .article-split-pane {
+  .article-layout.has-aside,
+  .article-layout.has-aside.is-railed-off { grid-template-columns: minmax(0, 1fr); }
+  .article-split-pane {
     position: fixed;
     inset: 0;
     z-index: 60;
     max-height: none;
-    border: 0;
-    border-radius: 0;
+    border-left: 0;
   }
-  .asplit-head { border-radius: 0; }
 }
diff --git a/frontend/src/pages/ArticleSplitView.test.jsx b/frontend/src/pages/ArticleSplitView.test.jsx
index 897c452..e1e43ce 100644
--- a/frontend/src/pages/ArticleSplitView.test.jsx
+++ b/frontend/src/pages/ArticleSplitView.test.jsx
@@ -68,21 +68,25 @@ describe('reading a cross-reference beside the article', () => {
 
     // The article that sent the reader there is still on the page, unmoved.
     expect(screen.getByText(/Fever alone rarely explains it/)).toBeInTheDocument()
-    expect(document.querySelector('.article-split')).toHaveClass('is-open')
-    expect(document.querySelector('.article-page')).toHaveClass('is-split')
+    // The pane is a third column of the reading grid, not a page nested inside
+    // the page — which is what the old `.article-split` wrapper made it.
+    expect(document.querySelector('.article-layout')).toHaveClass('has-aside')
+    expect(document.querySelector('.article-layout > .article-split-pane')).toBeInTheDocument()
   })
 
-  it('brings the whole reader with it: contents, and sections that expand', async () => {
+  it('is prose in the pane, not a second reader with a rail of its own', async () => {
     mount()
     await screen.findByText(/Fever alone rarely explains it/)
     await openSplit('meningitis')
     const pane = await screen.findByRole('region', { name: 'Split view: Meningitis' })
 
-    // The pane is the same reader as the page behind it — so a view of one
-    // section is shown as prose there too, with no heading repeating the view
-    // and no contents list of a single entry.
+    // It used to render the whole reader — contents rail, depth switch,
+    // collapsed sections — into a column half the width of the page. There is
+    // one rail on this screen, and it belongs to the article behind the pane.
     expect(within(pane).getByText('Neck stiffness')).toBeInTheDocument()
     expect(within(pane).queryByRole('button', { name: 'Signs' })).not.toBeInTheDocument()
+    expect(pane.querySelector('.article-sections')).toBeNull()
+    expect(document.querySelectorAll('.article-sections')).toHaveLength(1)
   })
 
   it('closing it gives the page back its single column', async () => {
@@ -93,8 +97,7 @@ describe('reading a cross-reference beside the article', () => {
 
     await userEvent.click(within(pane).getByRole('button', { name: 'Close split view' }))
     expect(screen.queryByRole('region', { name: /^Split view/ })).not.toBeInTheDocument()
-    expect(document.querySelector('.article-split')).not.toHaveClass('is-open')
-    expect(document.querySelector('.article-page')).not.toHaveClass('is-split')
+    expect(document.querySelector('.article-layout')).not.toHaveClass('has-aside')
     expect(screen.getByText(/Fever alone rarely explains it/)).toBeInTheDocument()
   })
 
@@ -109,10 +112,17 @@ describe('reading a cross-reference beside the article', () => {
     const card = await screen.findByRole('tooltip')
     await userEvent.click(within(card).getByRole('button', { name: /split view/i }))
     await waitFor(() => expect(api.get).toHaveBeenCalledWith('/articles/9'))
-    expect(await screen.findByRole('region', { name: 'Split view: Sepsis' })).toBeInTheDocument()
+    const deeper = await screen.findByRole('region', { name: 'Split view: Sepsis' })
     expect(document.querySelectorAll('.article-split-pane')).toHaveLength(1)
     // The article on the left is where it was; only the pane changed.
     expect(screen.getByText(/Fever alone rarely explains it/)).toBeInTheDocument()
+
+    // And the reference that sent you here is one press away, because losing
+    // your place is the thing split view exists to prevent. There was no way
+    // back before this but the browser, which takes the article with it.
+    await userEvent.click(within(deeper).getByRole('button', { name: /Back to the previous/ }))
+    expect(await screen.findByRole('region', { name: 'Split view: Meningitis' })).toBeInTheDocument()
+    expect(document.querySelectorAll('.article-split-pane')).toHaveLength(1)
   })
 
   it('closes on Escape, the way anything laid over the page should', async () => {
diff --git a/frontend/src/pages/ArticlesPage.css b/frontend/src/pages/ArticlesPage.css
index b794aa8..c2af834 100644
--- a/frontend/src/pages/ArticlesPage.css
+++ b/frontend/src/pages/ArticlesPage.css
@@ -15,55 +15,143 @@
 .breadcrumbs a { color: var(--primary); text-decoration: none; }
 .article-header { display: flex; justify-content: space-between; align-items: center; gap: 10px; flex-wrap: wrap; margin-bottom: 12px; }
 .article-header-actions { display: flex; gap: 8px; }
-.article-layout { display: grid; grid-template-columns: 240px 1fr; gap: 20px; align-items: start; }
+/* ── The reading layout ───────────────────────────────────────────────
+   Rail flush to the left edge of the window, prose taking everything to the
+   right of it. `--article-top` is the measured height of the site header, set
+   by the reader: the navbar's strip collapses as you scroll, and a number
+   written down here would go stale the moment that changes. */
+
+.app-main.is-bleed { width: 100%; padding: 0; }
+/* The navbar keeps 32px of air beneath it for pages that are cards on a
+   background. A reading page is not one — the rail and the article run to the
+   window edges, and a band of page showing above them reads as a gap where
+   something failed to load. */
+.article-page.is-reading { max-width: none; margin: -32px 0 0; padding: 0; }
+.article-notices { max-width: 1080px; margin: 0 auto; padding: 12px 28px 0; }
+
+.article-layout {
+  --article-top: 98px;
+  display: grid;
+  grid-template-columns: 272px minmax(0, 1fr);
+  align-items: start;
+}
 /* A rail, not a card: the contents of a long article should stay in view for
    its whole length, scrolling on their own when there are more sections than
-   screen. */
+   screen. It keeps its own scroll so the page behind it never moves. */
 .article-sections {
-  position: sticky; top: 76px; max-height: calc(100dvh - 96px); overflow-y: auto;
-  background: var(--card-bg); border: 1px solid var(--border);
-  border-radius: var(--card-radius); padding: 14px;
+  position: sticky;
+  top: var(--article-top);
+  height: calc(100dvh - var(--article-top));
+  /* The collapse handle hangs over the boundary, so nothing here may clip. */
+  overflow: visible;
+  background: var(--bg);
+  border-right: 1px solid var(--border);
 }
-.article-sections h4 { margin: 0 0 8px; font-size: .78rem; text-transform: uppercase; letter-spacing: .05em; color: var(--text-muted); }
+.article-rail-scroll { height: 100%; overflow-y: auto; padding: 16px 12px 28px 20px; }
+.article-sections h4 { margin: 0 0 10px; font-size: .82rem; font-weight: 700; line-height: 1.35; color: var(--text); }
+
 /* Collapsing it hands the width to the prose, which is what a long table or a
-   wide image needs and what nothing else on the page can give it. */
-.article-layout.is-railed-off { grid-template-columns: 34px 1fr; }
-.article-layout.is-railed-off .article-sections { padding: 6px; }
-.article-layout.is-railed-off .article-sections h4,
-.article-layout.is-railed-off .article-sections ul { display: none; }
-.article-rail-toggle {
+   wide image needs and what nothing else on the page can give it. Remembered
+   between articles, because it is a statement about how you read. */
+.article-layout.is-railed-off { grid-template-columns: 30px minmax(0, 1fr); }
+.article-layout.is-railed-off .article-sections { display: none; }
+
+.article-rail-hide, .article-rail-reopen {
   display: flex; align-items: center; justify-content: center;
-  width: 100%; min-height: 34px; margin-bottom: 8px; padding: 4px;
-  background: none; border: 1px solid var(--border); border-radius: 8px;
-  color: var(--text-muted); font: inherit; font-size: 1rem; cursor: pointer;
+  width: 26px; height: 26px; padding: 0;
+  background: var(--card-bg); border: 1px solid var(--border); border-radius: 50%;
+  color: var(--text-muted); font: inherit; font-size: 1rem; line-height: 1; cursor: pointer;
 }
-.article-rail-toggle:hover { border-color: var(--primary); color: var(--primary); }
-.article-layout.is-railed-off .article-rail-toggle { margin-bottom: 0; }
+.article-rail-hide:hover, .article-rail-reopen:hover { border-color: var(--primary); color: var(--primary); }
+/* On the boundary between the rail and the prose — where the reader is looking
+   when they decide they want the width. */
+.article-rail-hide { position: absolute; top: 16px; right: -13px; z-index: 3; }
+/* And where the rail was, so putting it back is where you last saw it. */
+.article-rail-reopen { position: sticky; top: calc(var(--article-top) + 16px); margin: 16px 0 0 2px; }
+
 .article-sections ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 2px; }
-.section-link { width: 100%; text-align: left; background: none; border: none; border-radius: 6px; padding: 7px 10px; font-size: .85rem; color: var(--text); cursor: pointer; }
+.section-link { width: 100%; text-align: left; background: none; border: none; border-radius: 6px; padding: 7px 10px; font-size: .84rem; line-height: 1.4; color: var(--text); cursor: pointer; }
 .section-link:hover { background: var(--hover, #eef4fb); }
 .section-link.active { background: var(--primary-soft, #dcebfa); color: var(--primary); font-weight: 600; }
-.article-content { min-width: 0; background: var(--card-bg); border: 1px solid var(--border); border-radius: var(--card-radius); padding: 22px 26px; }
+
+.article-content {
+  min-width: 0;
+  background: var(--card-bg);
+  padding: 14px clamp(20px, 3.5vw, 56px) 48px;
+  min-height: calc(100dvh - var(--article-top));
+}
 .article-content h2 { margin-top: 0; }
 .article-content img { max-width: 100%; border-radius: 8px; }
 .article-content table { border-collapse: collapse; width: 100%; margin: 12px 0; }
 .article-content td, .article-content th { border: 1px solid var(--border); padding: 6px 10px; }
-.article-updated { font-size: .76rem; color: var(--text-subtle); margin: 0 0 10px; }
-.article-summary { font-size: .95rem; color: var(--text-muted); border-left: 3px solid var(--primary); padding-left: 10px; margin: 0 0 16px; }
-.article-drawer-toggle { display: none; margin-bottom: 10px; }
+
+/* Three steps, because a reader wants bigger or smaller and nothing finer. */
+.article-text-s { font-size: .92rem; }
+.article-text-m { font-size: 1rem; }
+.article-text-l { font-size: 1.12rem; }
+
+/* The icon toolbar sits above the title, opposite the trail back to the
+   library — the two things you do with an article that are not reading it. */
+.article-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; flex-wrap: wrap; padding-top: 10px; }
+.article-trail { min-width: 0; }
+.article-trail .breadcrumbs { margin-bottom: 0; }
+.article-tools { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; }
+.article-tool {
+  display: inline-flex; align-items: baseline; justify-content: center; gap: 1px;
+  min-width: 32px; height: 32px; padding: 0 8px;
+  background: none; border: 1px solid var(--border); border-radius: 8px;
+  font: inherit; font-size: .95rem; line-height: 1; color: var(--text-muted); cursor: pointer;
+}
+.article-tool:hover { border-color: var(--primary); color: var(--primary); }
+.article-tool.is-on { border-color: var(--primary); color: var(--primary); background: var(--primary-soft, #dcebfa); }
+.article-tool-a { font-size: .72rem; }
+
+.article-title { margin: 6px 0 0; font-size: 1.75rem; line-height: 1.2; }
+.article-updated { font-size: .76rem; color: var(--text-subtle); margin: 8px 0 0; }
+.article-summary { font-size: .95em; color: var(--text-muted); border-left: 3px solid var(--primary); padding-left: 12px; margin: 14px 0 4px; }
+.article-summary p:last-child { margin-bottom: 0; }
+
+/* Contents on a narrow screen, where there is no room for a rail beside prose. */
+.article-drawer-toggle {
+  display: none; align-items: center; gap: 6px; height: 32px; padding: 0 12px;
+  background: var(--card-bg); border: 1px solid var(--border); border-radius: 8px;
+  font: inherit; font-size: .82rem; color: var(--text); cursor: pointer;
+}
 .article-linked { margin-top: 22px; border-top: 1px solid var(--border); padding-top: 14px; }
 .article-linked h3 { margin: 0 0 10px; font-size: 1rem; }
 .linked-card { display: flex; justify-content: space-between; align-items: center; gap: 10px; border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px; margin-bottom: 8px; flex-wrap: wrap; }
 .article-edit { display: flex; flex-direction: column; gap: 8px; }
 .article-edit .form-label { margin-top: 6px; }
+
+@media (prefers-reduced-motion: reduce) {
+  .article-sections { transition: none !important; }
+}
+
 @media (max-width: 820px) {
-  .article-layout { grid-template-columns: 1fr; }
-  .article-sections { position: static; display: none; max-height: none; }
-  .article-rail-toggle { display: none; }
-  .article-layout.is-railed-off { grid-template-columns: 1fr; }
-  .article-sections.open { display: block; }
-  .article-drawer-toggle { display: inline-block; }
-  .article-content { padding: 16px; }
+  /* No room for a rail beside prose. The contents become a panel over the
+     page, opened from the article's own bar — the site menu stays on the
+     navbar's button, so the two never compete for the same thumb. */
+  .article-layout, .article-layout.is-railed-off { grid-template-columns: minmax(0, 1fr); }
+  .article-sections {
+    position: fixed;
+    top: var(--article-top); bottom: 0; left: 0;
+    z-index: 45;
+    width: min(320px, 86vw);
+    height: auto;
+    transform: translateX(-101%);
+    /* Hidden rather than merely off-screen: a panel parked past the left edge
+       is still in the tab order, and tabbing into contents you cannot see is
+       how a keyboard reader loses the page. */
+    visibility: hidden;
+    border-right: 1px solid var(--border);
+    box-shadow: 8px 0 28px rgba(15, 23, 42, .18);
+    transition: transform .18s ease, visibility .18s;
+  }
+  .article-sections.open { transform: none; visibility: visible; }
+  .article-rail-hide, .article-rail-reopen { display: none; }
+  .article-drawer-toggle { display: inline-flex; }
+  .article-content { padding: 12px 16px 40px; min-height: 0; }
+  .article-title { font-size: 1.4rem; }
 }
 .comment-section { margin-top: 22px; border-top: 1px solid var(--border); padding-top: 14px; }
 .comment-heading { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; margin-bottom: 10px; }
@@ -156,10 +244,27 @@
    An article is a reference you consult, so it opens as a contents page:
    headings only, each expanding where it sits. */
 
-.asec-controls { display: flex; justify-content: flex-end; margin: 18px 0 4px; }
+/* The row above the sections. It parks under the site header as you read, so
+   the depth switch and the expand control stay reachable and the trail can say
+   where in the article you have got to once the title has scrolled away. */
+.asec-controls {
+  position: sticky;
+  top: var(--article-top);
+  z-index: 12;
+  display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap;
+  margin: 16px 0 0;
+  padding: 8px 0;
+  background: var(--card-bg);
+  border-bottom: 1px solid var(--border);
+}
+.asec-controls-left, .asec-controls-right { display: flex; align-items: center; gap: 10px; min-width: 0; }
+/* Where you are, once the heading has gone: article, then the section under
+   the reader's eye — the same one the rail marks. */
+.asec-where { min-width: 0; font-size: .8rem; color: var(--text-muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.asec-where-section { color: var(--text); font-weight: 600; }
 
 .asec-list { border-top: 1px solid var(--border); }
-.asec { scroll-margin-top: 84px; border-bottom: 1px solid var(--border); }
+.asec { scroll-margin-top: calc(var(--article-top, 98px) + 56px); border-bottom: 1px solid var(--border); }
 .asec-heading { margin: 0; font-size: 1rem; }
 
 .asec-head {
@@ -178,7 +283,9 @@
 }
 .asec-head[aria-expanded='true'] .asec-chevron { transform: rotate(180deg); }
 
-.asec-body { padding: 0 8px 18px; font-size: 0.95rem; line-height: 1.65; }
+/* `em`, not `rem`: the text-size control sets a size on the article and the
+   prose inside it has to follow. */
+.asec-body { padding: 0 8px 18px; font-size: 0.95em; line-height: 1.65; }
 .asec-body > :first-child { margin-top: 0; }
 
 /* A sub-section is drawn inside its parent, indented and quieter, so the
@@ -200,15 +307,23 @@
   .asec-body { font-size: 0.92rem; }
 }
 
-/* One topic, three readings. */
-.asec-controls { display: flex; align-items: center; gap: 10px; justify-content: space-between; flex-wrap: wrap; }
+/* One topic, three readings — where AMBOSS puts High-yield, at the right of
+   the row over the sections. The rail is filtered by the same choice, so the
+   contents can never list a section the body is no longer showing. */
 .aview-switch { display: inline-flex; gap: 2px; padding: 3px; background: var(--bg); border: 1px solid var(--border); border-radius: 9px; }
 .aview {
   min-height: 34px; padding: 6px 13px; border: 0; border-radius: 7px; cursor: pointer;
   background: none; font: inherit; font-size: 0.83rem; font-weight: 600; color: var(--text-muted);
 }
 .aview:hover { color: var(--text); }
-.aview.is-active { background: var(--card-bg); color: var(--primary); box-shadow: 0 1px 2px rgba(15,23,42,0.08); }
+/* Loud on purpose: this is the control that decides how much of the topic is
+   on screen, and a reader who cannot see which way it is set cannot explain
+   why two thirds of the contents just went away. */
+.aview.is-active {
+  background: var(--primary); color: #fff;
+  box-shadow: 0 1px 3px rgba(15, 23, 42, .22);
+}
+.aview.is-active:hover { color: #fff; }
 
 /* Sources for the whole article, not markers scattered through the prose. */
 .article-references { margin-top: 26px; padding-top: 14px; border-top: 1px solid var(--border); }
@@ -218,6 +333,11 @@
 .article-ref-title { color: var(--text); font-weight: 600; }
 .article-ref-pages { font-variant-numeric: tabular-nums; }
 
+@media (max-width: 900px) {
+  /* Four things in a bar this narrow is three too many; the rail and the
+     heading already say where you are. */
+  .asec-where { display: none; }
+}
 @media (max-width: 640px) {
   .asec-controls { gap: 8px; }
   .aview { padding: 6px 10px; font-size: 0.79rem; }
diff --git a/frontend/src/pages/ArticlesPage.jsx b/frontend/src/pages/ArticlesPage.jsx
index d0df7b7..a309c6b 100644
--- a/frontend/src/pages/ArticlesPage.jsx
+++ b/frontend/src/pages/ArticlesPage.jsx
@@ -200,6 +200,10 @@ export function ArticlePage() {
   const [showRefine, setShowRefine] = useState(false)
   const [refineText, setRefineText] = useState('')
   const navigate = useNavigate()
+  // Reading claims the window; editing hands it back. Width only — the
+  // navbar's own section strip is left alone, because every link on it is
+  // somewhere a reader may legitimately want to go mid-article.
+  useClaimFullBleed(!editing)
 
   useEffect(() => {
     if (idParam) { setId(idParam); return }
@@ -332,6 +336,10 @@ export function ArticlePage() {
     </>
   )
 
+  // Moderator business, and rare: kept above the reading rather than folded
+  // into it, with the page's gutters back so an alert is not flush to the
+  // window edge.
+  const hasNotices = !!error || (showRefine && user?.is_moderator)
   const notices = (
     <>
       {error && <div className="form-error" role="alert">{error}</div>}
@@ -391,7 +399,7 @@ export function ArticlePage() {
        gutters: a form field two thousand pixels wide is nobody's idea of an
        improvement. */
     <div className="article-page is-reading">
-      {notices && <div className="article-notices">{notices}</div>}
+      {hasNotices && <div className="article-notices">{notices}</div>}
       <SplitViewProvider value={splitView}>
         <ArticleReader article={article} activeSection={activeSection} onOpenSection={openSection}
           breadcrumbs={breadcrumbs}
diff --git a/frontend/src/pages/ArticlesPage.test.jsx b/frontend/src/pages/ArticlesPage.test.jsx
index 8a1a14f..45e35e6 100644
--- a/frontend/src/pages/ArticlesPage.test.jsx
+++ b/frontend/src/pages/ArticlesPage.test.jsx
@@ -208,6 +208,69 @@ describe('topic reading', () => {
     expect(layout).not.toHaveClass('is-railed-off')
   })
 
+  // 58 summaries in the library contain a cross-reference, and every one of
+  // them was printed at the reader as `[[288|eczema]]` — the syntax an educator
+  // writes a link in, shown to the person it was written for.
+  it('renders a summary cross-reference as a link on the article', async () => {
+    api.get.mockImplementation(url => {
+      if (url === '/articles/1') return Promise.resolve({ data: { ...article, summary: 'Often confused with [[288|eczema]].', sections: [] } })
+      return Promise.resolve({ data: [] })
+    })
+    render(<MemoryRouter initialEntries={['/articles/1']}><Routes><Route path="/articles/:id" element={<ArticlePage />} /></Routes></MemoryRouter>)
+
+    const summary = await screen.findByText(/Often confused with/)
+    expect(summary).not.toHaveTextContent('[[288|eczema]]')
+    expect(within(summary).getByRole('link', { name: 'eczema' })).toHaveAttribute('href', '/articles/288')
+  })
+
+  // The same summary in a list is not the same thing: the card is itself a
+  // link, so a live cross-reference inside it would swallow the click that was
+  // meant to open the article. Flattened to its words, never shown raw.
+  it('flattens a summary cross-reference to its words in a list', async () => {
+    api.get.mockImplementation(url => {
+      if (url === '/question-categories/') return Promise.resolve({ data: [] })
+      if (url === '/articles/') return Promise.resolve({ data: [{ ...article, summary: 'Often confused with [[288|eczema]].' }] })
+      return Promise.resolve({ data: [] })
+    })
+    render(<MemoryRouter initialEntries={['/articles']}><Routes><Route path="/articles" element={<ArticlesPage />} /></Routes></MemoryRouter>)
+    await screen.findByText('Febrile seizures')
+    await userEvent.type(screen.getByLabelText('Search articles'), 'febrile')
+
+    const card = await screen.findByRole('link', { name: /Febrile seizures/ })
+    expect(card).toHaveTextContent('Often confused with eczema.')
+    expect(card).not.toHaveTextContent('[[288|eczema]]')
+    expect(within(card).queryByRole('link')).toBeNull()
+  })
+
+  // Short is our high-yield. The contents are filtered by the same choice as
+  // the body, so the rail can never offer a heading the article is no longer
+  // showing — which is the failure worth guarding, not the switch itself.
+  it('keeps the contents rail in step with the depth being read', async () => {
+    const layered = { ...article, sections: [
+      { id: 'a'.repeat(32), slug: 'key', title: 'Key points', content: 'Key body', variant: 'short' },
+      { id: 'b'.repeat(32), slug: 'more', title: 'Worth knowing', content: 'More body', variant: 'short' },
+      { id: 'c'.repeat(32), slug: 'patho', title: 'Pathophysiology', content: 'Long body', variant: 'long' },
+      { id: 'd'.repeat(32), slug: 'mx', title: 'Management', content: 'Management body', variant: 'long' },
+    ] }
+    api.get.mockImplementation(url => {
+      if (url === '/articles/1') return Promise.resolve({ data: layered })
+      return Promise.resolve({ data: [] })
+    })
+    render(<MemoryRouter initialEntries={['/articles/1']}><Routes><Route path="/articles/:id" element={<ArticlePage />} /></Routes></MemoryRouter>)
+
+    await screen.findByText('Introduction markdown')
+    const toc = () => document.querySelector('.article-sections')
+    expect(within(toc()).getByRole('button', { name: 'Key points' })).toBeInTheDocument()
+    expect(within(toc()).queryByRole('button', { name: 'Pathophysiology' })).toBeNull()
+    expect(screen.getByRole('tab', { name: 'Short' })).toHaveAttribute('aria-selected', 'true')
+
+    await userEvent.click(screen.getByRole('tab', { name: 'Long' }))
+    expect(within(toc()).getByRole('button', { name: 'Pathophysiology' })).toBeInTheDocument()
+    expect(within(toc()).queryByRole('button', { name: 'Key points' })).toBeNull()
+    expect(screen.queryByText('Key body')).not.toBeInTheDocument()
+    expect(screen.getByRole('tab', { name: 'Long' })).toHaveAttribute('aria-selected', 'true')
+  })
+
   it('nests a sub-section under its parent and keeps references last', async () => {
     const nested = { ...article, sections: [
       { id: 'a'.repeat(32), slug: 'ros', title: 'Review of systems', content: 'ROS body' },