diff --git a/frontend/src/components/BootGate.tsx b/frontend/src/components/BootGate.tsx
index 7becdaf7..7b524cf9 100644
--- a/frontend/src/components/BootGate.tsx
+++ b/frontend/src/components/BootGate.tsx
@@ -30,7 +30,7 @@ import { LoadingState, StateMessage } from "./ui/QueryState";
  * Suspense fallback after it and the first page's own loading state keep one clock (see LoadingState). */
 export function BootScreen() {
   return (
-    <div className="min-h-screen grid place-items-center">
+    <div className="min-h-dvh grid place-items-center">
       <LoadingState since={0} delayMs={400} />
     </div>
   );
@@ -121,7 +121,7 @@ export default function BootGate({ children }: { children: ReactNode }) {
         : null;
   if (failed)
     return (
-      <div className="min-h-screen grid place-items-center">
+      <div className="min-h-dvh grid place-items-center">
         <StateMessage tone="error" onRetry={() => failed.refetch()}>
           {t("common.somethingWrong")}
         </StateMessage>
diff --git a/frontend/src/components/ErrorBoundary.tsx b/frontend/src/components/ErrorBoundary.tsx
index 1d9d6646..05c2225c 100644
--- a/frontend/src/components/ErrorBoundary.tsx
+++ b/frontend/src/components/ErrorBoundary.tsx
@@ -41,7 +41,7 @@ export default class ErrorBoundary extends Component<Props, State> {
     if (this.state.crashed) {
       if (reloadingForNewBuild()) return null;
       return (
-        <div className="min-h-screen grid place-items-center text-muted p-6 text-center">
+        <div className="min-h-dvh grid place-items-center text-muted p-6 text-center">
           <div>
             <div className="text-lg font-semibold text-fg mb-1">
               {i18n.t("errors.boundary.title")}
diff --git a/frontend/src/components/IssueComposer.tsx b/frontend/src/components/IssueComposer.tsx
index abe9f333..0616b52e 100644
--- a/frontend/src/components/IssueComposer.tsx
+++ b/frontend/src/components/IssueComposer.tsx
@@ -756,7 +756,7 @@ function ReviewList({
           {t("recorder.composer.reviewDone")}
         </Button>
       </div>
-      <ul className="max-h-[60vh] overflow-y-auto rounded-xl border border-border bg-bg/60 font-mono text-xs">
+      <ul className="max-h-[60dvh] overflow-y-auto rounded-xl border border-border bg-bg/60 font-mono text-xs">
         {rows.map((row) => {
           const tag = LEVEL_TAG[row.level];
           const off = excluded.has(row.id);
@@ -813,7 +813,7 @@ function IssuePreview({
     return (
       <div className="flex flex-col gap-1.5">
         <p className="text-xs text-muted">{t("recorder.composer.previewLocal")}</p>
-        <pre className="max-h-[60vh] overflow-auto whitespace-pre-wrap rounded-xl border border-border bg-bg/60 p-3 font-mono text-xs">
+        <pre className="max-h-[60dvh] overflow-auto whitespace-pre-wrap rounded-xl border border-border bg-bg/60 p-3 font-mono text-xs">
           {text}
         </pre>
       </div>
diff --git a/frontend/src/components/LibraryPlayer.tsx b/frontend/src/components/LibraryPlayer.tsx
index 4bdbc3d6..820ba4bb 100644
--- a/frontend/src/components/LibraryPlayer.tsx
+++ b/frontend/src/components/LibraryPlayer.tsx
@@ -63,7 +63,7 @@ export default function LibraryPlayer({ job, onClose }: { job: DownloadJob; onCl
           controls
           autoPlay
           playsInline
-          className="w-full max-h-[70vh] rounded-lg bg-black object-contain"
+          className="w-full max-h-[70dvh] rounded-lg bg-black object-contain"
         >
           {t("downloads.player.unsupported")}
         </video>
diff --git a/frontend/src/components/PlexSearchBox.tsx b/frontend/src/components/PlexSearchBox.tsx
index 74734eee..7499cc60 100644
--- a/frontend/src/components/PlexSearchBox.tsx
+++ b/frontend/src/components/PlexSearchBox.tsx
@@ -141,7 +141,7 @@ export default function PlexSearchBox() {
             id={listId}
             role="listbox"
             aria-label={t("plex.suggest.aria")}
-            className={`${SURFACE.menu} absolute left-0 right-0 top-full z-menu mt-2 max-h-[70vh] overflow-y-auto animate-[popIn_0.16s_ease]`}
+            className={`${SURFACE.menu} absolute left-0 right-0 top-full z-menu mt-2 max-h-[70dvh] overflow-y-auto animate-[popIn_0.16s_ease]`}
           >
             {suggestions.length === 0 && suggestQ.isFetching && (
               <div className="px-3 py-2 text-sm text-muted">{t("plex.loading")}</div>
diff --git a/frontend/src/components/SetupWizard.tsx b/frontend/src/components/SetupWizard.tsx
index 75b6aa12..93b9190d 100644
--- a/frontend/src/components/SetupWizard.tsx
+++ b/frontend/src/components/SetupWizard.tsx
@@ -305,7 +305,7 @@ export default function SetupWizard() {
 }
 
 function Centered({ children }: { children: React.ReactNode }) {
-  return <div className="min-h-screen bg-bg text-fg grid place-items-center p-4">{children}</div>;
+  return <div className="min-h-dvh bg-bg text-fg grid place-items-center p-4">{children}</div>;
 }
 
 function Section({
diff --git a/frontend/src/components/VideoEditor.tsx b/frontend/src/components/VideoEditor.tsx
index 1ddb1db8..b4b1fe22 100644
--- a/frontend/src/components/VideoEditor.tsx
+++ b/frontend/src/components/VideoEditor.tsx
@@ -395,7 +395,7 @@ export default function VideoEditor({ job, onClose }: { job: DownloadJob; onClos
             onTimeUpdate={onTimeUpdate}
             onPlay={() => setPlaying(true)}
             onPause={() => setPlaying(false)}
-            className="w-full max-h-[42vh] mx-auto block object-contain"
+            className="w-full max-h-[42dvh] mx-auto block object-contain"
             playsInline
           />
           {cropOn && picRect && (
diff --git a/frontend/src/components/Welcome.tsx b/frontend/src/components/Welcome.tsx
index 3a082852..82615fb9 100644
--- a/frontend/src/components/Welcome.tsx
+++ b/frontend/src/components/Welcome.tsx
@@ -70,7 +70,7 @@ export default function Welcome({ verify }: { verify: VerifyEntry }) {
   const [zoomed, setZoomed] = useState<{ src: string; label: string } | null>(null);
   const open = (src: string, label: string) => setZoomed({ src, label });
   return (
-    <div className="min-h-screen bg-bg text-fg overflow-y-auto">
+    <div className="min-h-dvh bg-bg text-fg overflow-y-auto">
       <header className="flex items-center justify-between px-5 sm:px-8 py-4">
         <div className="text-xl font-bold tracking-tight">
           Sift<span className="text-accent">lode</span>
@@ -324,7 +324,7 @@ function Lightbox({ src, label, onClose }: { src: string; label: string; onClose
         <img
           src={src}
           alt={label}
-          className="max-h-[82vh] max-w-[92vw] w-auto h-auto rounded-xl border border-border object-contain shadow-2xl"
+          className="max-h-[82dvh] max-w-[92vw] w-auto h-auto rounded-xl border border-border object-contain shadow-2xl"
         />
         <figcaption className="text-sm text-muted">{label}</figcaption>
       </figure>
diff --git a/frontend/src/components/legal/LegalLayout.tsx b/frontend/src/components/legal/LegalLayout.tsx
index 706315d4..60e6f2d2 100644
--- a/frontend/src/components/legal/LegalLayout.tsx
+++ b/frontend/src/components/legal/LegalLayout.tsx
@@ -78,7 +78,7 @@ export default function LegalLayout({ title, children }: { title: string; childr
     document.title = `${title} · Siftlode`;
   }, [title]);
   return (
-    <div className="min-h-screen bg-bg text-fg">
+    <div className="min-h-dvh bg-bg text-fg">
       <div className="mx-auto w-[min(92vw,720px)] py-12">
         <div className="mb-8 flex items-center justify-between gap-4">
           <a href="/" className="inline-block text-2xl font-bold tracking-tight">
diff --git a/frontend/src/components/ui/CommandPalette.tsx b/frontend/src/components/ui/CommandPalette.tsx
index b5211f36..e0786f03 100644
--- a/frontend/src/components/ui/CommandPalette.tsx
+++ b/frontend/src/components/ui/CommandPalette.tsx
@@ -173,7 +173,7 @@ function CommandPaletteBody({ onClose, groups }: { onClose: () => void; groups:
       const from = Math.max(activeIndex, 0);
       setPicked(flat[(from + step + flat.length) % flat.length]!.id);
     } else if (e.key === "PageDown" || e.key === "PageUp") {
-      // A page at a time, stopping at the ends (lib/listPaging). The list is 50vh and group headings
+      // A page at a time, stopping at the ends (lib/listPaging). The list is 50dvh and group headings
       // eat into it, so the page is measured. Home/End stay the field's own (caret to the query's ends).
       e.preventDefault();
       const list = listRef.current;
@@ -230,7 +230,7 @@ function CommandPaletteBody({ onClose, groups }: { onClose: () => void; groups:
         role="listbox"
         aria-label={t("palette.title")}
         hidden={flat.length === 0}
-        className="mt-3 max-h-[50vh] overflow-y-auto"
+        className="mt-3 max-h-[50dvh] overflow-y-auto"
       >
         {visible.map((g) => (
           <div
diff --git a/frontend/src/components/ui/Modal.tsx b/frontend/src/components/ui/Modal.tsx
index 8336db97..db4a855d 100644
--- a/frontend/src/components/ui/Modal.tsx
+++ b/frontend/src/components/ui/Modal.tsx
@@ -97,7 +97,7 @@ export default function Modal({
         drawer
           ? "justify-end"
           : top
-            ? "items-start justify-center p-4 pt-[8vh] sm:p-6 sm:pt-[10vh]"
+            ? "items-start justify-center p-4 pt-[8dvh] sm:p-6 sm:pt-[10dvh]"
             : "items-center justify-center p-4 sm:p-6"
       }`}
       onMouseDown={(e) => {
diff --git a/frontend/src/components/ui/tableHeader.tsx b/frontend/src/components/ui/tableHeader.tsx
index 46012e41..485f0d80 100644
--- a/frontend/src/components/ui/tableHeader.tsx
+++ b/frontend/src/components/ui/tableHeader.tsx
@@ -211,7 +211,7 @@ export function ColumnHead<T>({
   const [openFilter, setOpenFilter] = useState<string | null>(null);
 
   return (
-    <thead className="sticky top-0 z-base after:pointer-events-none after:absolute after:inset-x-0 after:top-full after:h-4 after:bg-[linear-gradient(to_bottom,var(--bg),transparent)] after:content-['']">
+    <thead className="sticky top-0 z-base fade-below">
       <tr className="text-muted [&>th]:shadow-[inset_0_-1px_0_var(--border)]">
         {columns.map((col) => {
           const isSorted = sort?.key === col.key;
diff --git a/frontend/src/lib/fadeEdge.contract.test.ts b/frontend/src/lib/fadeEdge.contract.test.ts
new file mode 100644
index 00000000..6762bc49
--- /dev/null
+++ b/frontend/src/lib/fadeEdge.contract.test.ts
@@ -0,0 +1,30 @@
+import { readdirSync, readFileSync } from "node:fs";
+
+import { describe, expect, it } from "vitest";
+
+// E28 S3d4 (B9). The header + fade edge is one recipe, the `fade-below` / `fade-below-panel` /
+// `fade-above-panel` utilities in index.css: a crisp band and a 1rem gradient of the colour under
+// it. The table header carried its own arbitrary-value copy of it, which a change to the recipe (its
+// height, its colour on a panel) would have left behind.
+function sources(): Array<[string, string]> {
+  const walk = (u: URL, prefix: string): Array<[string, string]> =>
+    readdirSync(u, { withFileTypes: true }).flatMap((e) => {
+      if (e.isDirectory()) return walk(new URL(`${e.name}/`, u), `${prefix}${e.name}/`);
+      if (!/\.tsx?$/.test(e.name) || e.name.includes(".test.")) return [];
+      return [
+        [`${prefix}${e.name}`, readFileSync(new URL(e.name, u), "utf-8")] as [string, string],
+      ];
+    });
+  return walk(new URL("../", import.meta.url), "");
+}
+
+describe("the fade edge", () => {
+  it("is the utility, never an arbitrary gradient of a surface colour", () => {
+    const copies = sources()
+      .filter(([, src]) =>
+        /linear-gradient\(to_(?:bottom|top),var\(--(?:bg|surface|card)\)/.test(src),
+      )
+      .map(([name]) => name);
+    expect(copies).toEqual([]);
+  });
+});
diff --git a/frontend/src/lib/viewportUnits.contract.test.ts b/frontend/src/lib/viewportUnits.contract.test.ts
new file mode 100644
index 00000000..720b1bb5
--- /dev/null
+++ b/frontend/src/lib/viewportUnits.contract.test.ts
@@ -0,0 +1,33 @@
+import { readdirSync, readFileSync } from "node:fs";
+
+import { describe, expect, it } from "vitest";
+
+// E28 S3d4 (E18.5's `h-screen` → `dvh`). `100vh` is the viewport with a mobile browser's toolbars
+// RETRACTED: on a tablet with the toolbar showing, an `h-screen` shell runs its bottom edge (the
+// last rows, a dialog's footer) under the toolbar. `dvh` follows the toolbar. A static `vh` size is
+// the same trap at a smaller scale, so the app sizes by `dvh` everywhere.
+function sources(): Array<[string, string]> {
+  const walk = (u: URL, prefix: string): Array<[string, string]> =>
+    readdirSync(u, { withFileTypes: true }).flatMap((e) => {
+      if (e.isDirectory()) return walk(new URL(`${e.name}/`, u), `${prefix}${e.name}/`);
+      if (!/\.tsx?$/.test(e.name) || e.name.includes(".test.")) return [];
+      return [
+        [`${prefix}${e.name}`, readFileSync(new URL(e.name, u), "utf-8")] as [string, string],
+      ];
+    });
+  return walk(new URL("../", import.meta.url), "");
+}
+
+// The Plex player's stage is sized with the 80vh × 1.25 zoom trick. It changes in S3f, where the
+// players are re-fitted for touch and verified by playing them on the tablet.
+const PENDING_S3F = new Set(["components/PlexPlayer.tsx"]);
+
+describe("viewport units", () => {
+  it("are dynamic: no h-screen / min-h-screen, no static vh", () => {
+    const hits = sources()
+      .filter(([name]) => !PENDING_S3F.has(name))
+      .filter(([, src]) => /\b(?:min-|max-)?h-screen\b|\d(?:\.\d+)?vh\b/.test(src))
+      .map(([name]) => name);
+    expect(hits).toEqual([]);
+  });
+});
diff --git a/frontend/src/main.tsx b/frontend/src/main.tsx
index 08db0e45..fac38dd9 100644
--- a/frontend/src/main.tsx
+++ b/frontend/src/main.tsx
@@ -121,7 +121,7 @@ createRoot(document.getElementById("root")!).render(
     {/* Around EVERY entry, the public ones too: a crash on a shared /watch link, or its chunk gone
         twice over after a release (lib/staleBuild), left a blank white page with no way on. */}
     <ErrorBoundary>
-      <Suspense fallback={<div style={{ minHeight: "100vh" }} />}>{root}</Suspense>
+      <Suspense fallback={<div style={{ minHeight: "100dvh" }} />}>{root}</Suspense>
     </ErrorBoundary>
   </React.StrictMode>,
 );