diff --git a/frontend/src/routes/MailLayout.tsx b/frontend/src/routes/MailLayout.tsx
index e65a357..f9d3a48 100644
--- a/frontend/src/routes/MailLayout.tsx
+++ b/frontend/src/routes/MailLayout.tsx
@@ -980,19 +980,22 @@ export function MailLayout() {
           {/* Plugin-contributed sidebar sections (SPEC §11.3 sidebar.section). */}
           {!collapsed && <PluginSlot name="sidebar.section" />}
         </nav>
+        {mobile && (
+          <div className="p-2 text-[15px]">
+            <InstallAppEntry onDone={() => setDrawerOpen(false)} />
+          </div>
+        )}
         <div className="border-t border-app-border p-2 text-[15px]">
-          {/* Settings has no phone layout yet either. */}
           <Link
             className={`flex items-center gap-2.5 rounded-lg py-2 text-app-muted hover:bg-app-hover hover:text-app-fg ${
               collapsed ? "justify-center px-0" : "px-3"
-            } ${mobile ? "hidden" : ""}`}
+            }`}
             title={collapsed ? t("nav.settings") : undefined}
             to="/settings"
           >
             <Icon name="settings" size={22} />
             {!collapsed && t("nav.settings")}
           </Link>
-          {mobile && <InstallAppEntry onDone={() => setDrawerOpen(false)} />}
           <button
             className={`wm-online-only flex w-full items-center gap-2.5 rounded-lg py-2 text-left text-app-muted hover:bg-app-hover hover:text-app-fg ${
               collapsed ? "justify-center px-0" : "px-3"
diff --git a/frontend/src/routes/settings/Settings.tsx b/frontend/src/routes/settings/Settings.tsx
index 51a9565..2560675 100644
--- a/frontend/src/routes/settings/Settings.tsx
+++ b/frontend/src/routes/settings/Settings.tsx
@@ -1,6 +1,6 @@
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { QRCodeSVG } from "qrcode.react";
-import { useEffect, useState } from "react";
+import { useEffect, useRef, useState } from "react";
 import { Link, useLocation, useNavigate, useParams, useSearchParams } from "react-router-dom";
 
 import { RichTextEditor } from "../../components/compose/RichTextEditor";
@@ -23,6 +23,7 @@ import {
 import { prefetchRecent } from "../../lib/offlinePrefetch";
 import { disablePush, enablePush, usePushState } from "../../lib/push";
 import { useTheme } from "../../lib/theme";
+import { useIsMobile } from "../../lib/useIsMobile";
 import { formatClock, getDateLocale, setTimeFormat } from "../../lib/timeFormat";
 import { PluginSlot } from "../../plugins/PluginSlot";
 import { usePluginSettingsSections } from "../../plugins/manifest";
@@ -48,13 +49,46 @@ export function Settings() {
   // plugin name, rather than being stacked at the bottom of Accounts.
   const pluginSections = usePluginSettingsSections();
   const isPluginSection = pluginSections.some((b) => b.plugin === params.section);
-  const section = (
-    addingAccount
-      ? "accounts"
-      : SECTIONS.includes(params.section as Section) || isPluginSection
-        ? params.section
-        : "profile"
-  ) as Section;
+  // A section named in the URL. Without one, a phone shows the list of
+  // sections; the desktop layout shows Profile.
+  const chosen = addingAccount || SECTIONS.includes(params.section as Section) || isPluginSection;
+  const section = (addingAccount ? "accounts" : chosen ? params.section : "profile") as Section;
+  const mobile = useIsMobile();
+
+  const content = (
+    <>
+      {addingAccount && <AccountWizard embedded onDone={() => navigate("/settings/accounts")} />}
+      {!addingAccount && section === "profile" && <ProfileSection />}
+      {!addingAccount && section === "security" && <SecuritySection />}
+      {!addingAccount && section === "accounts" && <AccountsSection />}
+      {section === "calendars" && <CalendarsSection />}
+      {section === "appearance" && <AppearanceSection />}
+      {section === "integrations" && <IntegrationsSection />}
+      {/* Plugin-contributed settings UI (SPEC §11.3 settings.page): one section
+          per plugin, selected from the nav like any built-in section. */}
+      {isPluginSection && (
+        <div className="max-w-5xl">
+          <PluginSlot name="settings.page" plugin={section} />
+        </div>
+      )}
+    </>
+  );
+  const entries = [
+    ...SECTIONS.map((s) => ({ key: s as string, label: t(`settings.${s}` as const) })),
+    ...pluginSections.map((b) => ({ key: b.plugin, label: b.title ?? b.plugin })),
+  ];
+
+  if (mobile) {
+    return (
+      <MobileSettings
+        from={from}
+        fromQuery={fromQuery}
+        entries={entries}
+        open={chosen ? section : null}
+        content={content}
+      />
+    );
+  }
 
   return (
     <div className="flex h-screen flex-col">
@@ -66,52 +100,153 @@ export function Settings() {
       </header>
       <div className="flex min-h-0 flex-1">
         <nav className="w-52 shrink-0 border-r border-app-border p-2">
-          {SECTIONS.map((s) => (
+          {entries.map((e) => (
             <Link
-              key={s}
-              to={`/settings/${s}${fromQuery}`}
+              key={e.key}
+              to={`/settings/${e.key}${fromQuery}`}
               className={`block rounded px-3 py-2 text-sm ${
-                section === s ? "bg-app-active font-medium text-app-fg" : "hover:bg-app-hover"
+                section === e.key ? "bg-app-active font-medium text-app-fg" : "hover:bg-app-hover"
               }`}
             >
-              {t(`settings.${s}` as const)}
-            </Link>
-          ))}
-          {pluginSections.map((b) => (
-            <Link
-              key={b.plugin}
-              to={`/settings/${b.plugin}${fromQuery}`}
-              className={`block rounded px-3 py-2 text-sm ${
-                section === (b.plugin as Section)
-                  ? "bg-app-active font-medium text-app-fg"
-                  : "hover:bg-app-hover"
-              }`}
-            >
-              {b.title ?? b.plugin}
+              {e.label}
             </Link>
           ))}
         </nav>
-        <main className="flex-1 overflow-y-auto p-6">
-          {addingAccount && <AccountWizard embedded onDone={() => navigate("/settings/accounts")} />}
-          {!addingAccount && section === "profile" && <ProfileSection />}
-          {!addingAccount && section === "security" && <SecuritySection />}
-          {!addingAccount && section === "accounts" && <AccountsSection />}
-          {section === "calendars" && <CalendarsSection />}
-          {section === "appearance" && <AppearanceSection />}
-          {section === "integrations" && <IntegrationsSection />}
-          {/* Plugin-contributed settings UI (SPEC §11.3 settings.page): one section
-              per plugin, selected from the nav like any built-in section. */}
-          {isPluginSection && (
-            <div className="max-w-5xl">
-              <PluginSlot name="settings.page" plugin={section} />
-            </div>
-          )}
-        </main>
+        <main className="flex-1 overflow-y-auto p-6">{content}</main>
       </div>
     </div>
   );
 }
 
+/**
+ * Settings on a phone: the sections as a full-width list; the chosen one slides
+ * in over it from the right and back out on ‹ Settings (or the phone's Back,
+ * since each section is its own URL).
+ */
+function MobileSettings({
+  from,
+  fromQuery,
+  entries,
+  open,
+  content,
+}: {
+  from: string;
+  fromQuery: string;
+  entries: { key: string; label: string }[];
+  open: string | null;
+  content: JSX.Element;
+}) {
+  const t = useT();
+  const navigate = useNavigate();
+  const location = useLocation();
+  // What the panel shows: the open section, and while it slides out, the one
+  // that was open.
+  const [shown, setShown] = useState<{ key: string; content: JSX.Element } | null>(
+    open ? { key: open, content } : null,
+  );
+  useEffect(() => {
+    if (open) setShown({ key: open, content });
+  }, [open, content]);
+  const key = open ?? shown?.key;
+  const title = entries.find((e) => e.key === key)?.label ?? "";
+
+  // Most sections open with their own name as a heading, which the header
+  // already shows: hide that one (plugin sections render later, hence the observer).
+  const mainRef = useRef<HTMLElement>(null);
+  useEffect(() => {
+    const main = mainRef.current;
+    if (!main || !title) return;
+    const mark = () => {
+      const first = main.querySelector("h1, h2, h3");
+      if (first && !first.hasAttribute("data-dup-title") && first.textContent?.trim() === title) {
+        first.setAttribute("data-dup-title", "");
+      }
+    };
+    mark();
+    const observer = new MutationObserver(mark);
+    observer.observe(main, { childList: true, subtree: true });
+    return () => observer.disconnect();
+  }, [title, key]);
+
+  const back = () => {
+    // Opened from the list: step back in history, so the phone's Back button
+    // and this one agree. Opened directly (a link, a reload): go to the list.
+    if ((location.state as { fromList?: boolean } | null)?.fromList) navigate(-1);
+    else navigate(`/settings${fromQuery}`, { replace: true });
+  };
+
+  return (
+    <div className="relative h-[100dvh] overflow-hidden bg-app-bg text-app-fg">
+      <div className="flex h-full flex-col pt-[env(safe-area-inset-top)]">
+        <header className="flex h-14 shrink-0 items-center gap-2 border-b border-app-border px-2">
+          <Link to={from} className="flex items-center rounded-lg px-2 py-2 text-app-accent" aria-label={t("nav.back")}>
+            <Chevron left />
+            <span className="ml-0.5">{t("nav.back")}</span>
+          </Link>
+          <h1 className="text-lg font-semibold">{t("settings.title")}</h1>
+        </header>
+        <nav className="flex-1 overflow-y-auto pb-[env(safe-area-inset-bottom)]">
+          {entries.map((e) => (
+            <Link
+              key={e.key}
+              to={`/settings/${e.key}${fromQuery}`}
+              state={{ fromList: true }}
+              className="flex items-center justify-between border-b border-app-border px-5 py-4 text-base active:bg-app-hover"
+            >
+              {e.label}
+              <span className="text-app-faint">
+                <Chevron />
+              </span>
+            </Link>
+          ))}
+        </nav>
+      </div>
+      <div
+        className={`absolute inset-0 flex flex-col bg-app-bg pt-[env(safe-area-inset-top)] transition-transform duration-300 ease-out ${
+          open ? "translate-x-0" : "translate-x-full"
+        } ${key ? "shadow-2xl" : ""}`}
+        onTransitionEnd={() => !open && setShown(null)}
+        aria-hidden={!open}
+      >
+        {key && (
+          <>
+            <header className="flex h-14 shrink-0 items-center gap-1 border-b border-app-border px-2">
+              <button
+                onClick={back}
+                className="flex items-center rounded-lg px-2 py-2 text-app-accent"
+                aria-label={t("settings.title")}
+              >
+                <Chevron left />
+                <span className="ml-0.5">{t("settings.title")}</span>
+              </button>
+              <h1 className="min-w-0 flex-1 truncate pr-3 text-center text-lg font-semibold">{title}</h1>
+              {/* Balances the back button, so the title sits in the middle. */}
+              <span className="invisible flex items-center px-2" aria-hidden>
+                <Chevron left />
+                <span className="ml-0.5">{t("settings.title")}</span>
+              </span>
+            </header>
+            <main
+              ref={mainRef}
+              className="flex-1 overflow-y-auto overflow-x-hidden p-4 pb-[calc(1rem+env(safe-area-inset-bottom))] [&_[data-dup-title]]:hidden"
+            >
+              {open ? content : shown?.content}
+            </main>
+          </>
+        )}
+      </div>
+    </div>
+  );
+}
+
+function Chevron({ left = false }: { left?: boolean }) {
+  return (
+    <svg viewBox="0 0 24 24" width={20} height={20} fill="none" stroke="currentColor" strokeWidth={2} aria-hidden>
+      <path d={left ? "M15 5l-7 7 7 7" : "M9 5l7 7-7 7"} strokeLinecap="round" strokeLinejoin="round" />
+    </svg>
+  );
+}
+
 function ProfileSection() {
   const t = useT();
   const { data } = useMe();
@@ -559,10 +694,11 @@ function AccountsSection() {
             ) : editing?.id === a.id && editing.mode === "signature" ? (
               <SignatureEditor accountId={a.id} onCancel={() => setEditing(null)} onSaved={close} />
             ) : (
-              <div className="flex items-center justify-between">
-                <span className="flex items-center gap-2">
-                  <span className="h-3 w-3 rounded-full" style={{ backgroundColor: a.color }} />
-                  <span>{a.email}</span>
+              // Wraps on a narrow screen: the actions move below the address.
+              <div className="flex flex-wrap items-center justify-between gap-x-4 gap-y-1.5">
+                <span className="flex min-w-0 flex-wrap items-center gap-x-2 gap-y-0.5">
+                  <span className="h-3 w-3 shrink-0 rounded-full" style={{ backgroundColor: a.color }} />
+                  <span className="min-w-0 break-all">{a.email}</span>
                   {a.state === "auth_failed" ? (
                     <span className="text-xs text-red-500" title={a.state_detail || undefined}>
                       {t("settings.stateAuthFailed")}
@@ -585,7 +721,7 @@ function AccountsSection() {
                     </>
                   )}
                 </span>
-                <span className="flex items-center gap-3">
+                <span className="flex flex-wrap items-center gap-x-3 gap-y-1 whitespace-nowrap">
                   {a.sync_window !== "all" && (
                     <button
                       className="text-xs text-app-accent disabled:opacity-50"