fix(studio): the sidebar footer takes the rail's tint over a wallpaper instead of a plate of its own

desktop/frontend-next/perf/effects.mjs

@@ -134,6 +134,26 @@ const timeLoops = (page) =>
   await ctx.close();
 }
 
+{
+  // The sidebar's footer is part of the rail: a plate of its own over the
+  // wallpaper reads as a second, whiter panel at the window's lower left.
+  for (const scheme of ["light", "dark"]) {
+    const ctx = await browser.newContext({ viewport: { width: 1200, height: 760 }, colorScheme: scheme });
+    await ctx.addInitScript(() => localStorage.setItem("rx-nav-rail", "off"));
+    const page = await ctx.newPage();
+    await page.goto(`${BASE.replace(/\?.*/, "")}?pack=photo`, { waitUntil: "networkidle" });
+    await page.waitForSelector(".app", { timeout: 15000 });
+    await page.mouse.click(8, 407);
+    await page.waitForSelector(".railfoot", { timeout: 5000 });
+    const paint = await page.evaluate(() => {
+      const alpha = (c) => (c.startsWith("rgba(") ? Number(c.split(",")[3].replace(")", "")) : c.includes("/") ? Number(c.split("/")[1].replace(")", "")) : 1);
+      return alpha(getComputedStyle(document.querySelector(".railfoot")).backgroundColor);
+    });
+    check(`${scheme}: the sidebar footer paints no plate over the wallpaper`, paint === 0, `alpha ${paint}`);
+    await ctx.close();
+  }
+}
+
 await browser.close();
 console.log(fails.length ? `\n${fails.length} failed:\n- ${fails.join("\n- ")}` : "\nall passed");
 process.exit(fails.length ? 1 : 0);

desktop/frontend-next/src/styles/studio.css

@@ -3268,14 +3268,10 @@ body { font-size: 14px; line-height: 1.75; }
 .studio-workspace-kind { color: var(--muted); }
 .studio-user-foot .acctrow:hover,
 .studio-settings:hover { background: var(--accent-wash); color: var(--text); }
-:root[data-bg] .railfoot {
-  background: color-mix(in srgb, var(--surface) 80%, transparent) !important;
-}
 :root[data-theme="light"][data-bg] :is(.rail, .chrome) {
   background: color-mix(in srgb, var(--page) 86%, transparent) !important;
 }
 :root[data-theme="light"][data-bg] .railfoot {
-  background: color-mix(in srgb, var(--surface) 90%, transparent) !important;
   box-shadow: 0 -1px color-mix(in srgb, var(--border) 62%, transparent);
 }
 :root[data-theme="light"] .studio-user-foot .ini[data-off] {