The scene stops heating the MacBook

"Terribly high CPU usage, the MacBook gets really hot" - a fanless MacBook
Air on a 144Hz screen. Measured on that machine with headed engines
(process CPU plus the per-process GPU time macOS keeps): an idle Aero
library cost LibreWolf ~110% CPU and ~230ms/s of GPU, the study feed ~130%,
Chromium up to ~57% CPU and ~350ms/s of GPU, Safari ~220-250ms/s of
WindowServer GPU. Priced one by one:

- the gradient mask on .ice-floats re-rendered the animated layer offscreen
  on every frame (~75 points of Gecko CPU). The floats now rise through a
  plain rectangular band clear of the header, the bottom chrome and the
  rail, and fade in and out inside it, so the clip never cuts a visible one;
- the overlay grain forced a backdrop readback per frame for a texture that
  measured a mean <=0.11/255 difference: removed;
- the invisible blob drift made every frame a full-screen redraw: the blobs
  are painted once;
- static glass (answer tiles, feedback panel, chips, inputs, dropzones,
  lists, segmented controls, Aero hint chips) re-blurred the moving scene
  every frame: only floating glass blurs now, and Aero's baked chat chrome
  drops a live blur that never showed under the bake;
- the scene also parks while the window has no focus and under any dialog
  or sheet scrim (.scene-pause); the loading icon is a compositor-run CSS
  animation instead of a framer-motion main-thread loop.

After, focused and animating: LibreWolf library 109% -> 33% CPU, study
134% -> 34%, chat 130% -> 42%; Chromium GPU 2.5-4.4x lower with 7-22 points
less CPU; Safari's WindowServer GPU -20-26% in Aero, about half in dark.
Unfocused or under a sheet: nothing. bubbles-test sweeps every float through
41 phases against the band and pins the parking and the cost contract;
tests/heat-probe.mjs (macOS) repeats the measurement; the suites find
Playwright's Chromium on macOS.

All 15 suites pass, lint clean, the contrast scan lost a finding. Version
0.6.7, SW v89.

Co-authored-by: Cursor <cursoragent@cursor.com>

components/UploadScreen.tsx

@@ -495,12 +495,12 @@ export function UploadScreen() {
               setDifficulty(option.value);
             }}
             className={cn(
-              "relative flex flex-col items-center gap-1 overflow-hidden rounded-2xl border px-2 py-3 text-center backdrop-blur-xl transition-colors",
+              "relative flex flex-col items-center gap-1 overflow-hidden rounded-2xl border px-2 py-3 text-center transition-colors",
               selected && isPhone
                 ? "border-transparent"
                 : selected
                   ? "border-accent-400 bg-accent-50/80 shadow-lift dark:bg-accent-500/20"
-                  : "border-white/60 bg-white/45 backdrop-blur-xl hover:bg-white/70 dark:border-white/12 dark:bg-white/[0.05]",
+                  : "border-white/60 bg-white/45 hover:bg-white/70 dark:border-white/12 dark:bg-white/[0.05]",
             )}
           >
             {selected && isPhone ? (
@@ -776,7 +776,7 @@ export function UploadScreen() {
                   autoComplete="off"
                   autoCapitalize="sentences"
                   spellCheck
-                  className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
+                  className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
                 />
               ) : null}
 
@@ -922,7 +922,7 @@ export function UploadScreen() {
                       onChange={(event) => setText(event.target.value)}
                       rows={4}
                       placeholder={t("upload.pastedPlaceholder")}
-                      className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
+                      className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
                     />
                   </div>
                   <div className="space-y-1.5">
@@ -942,7 +942,7 @@ export function UploadScreen() {
                       autoComplete="off"
                       autoCapitalize="sentences"
                       spellCheck={false}
-                      className="w-full rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
+                      className="w-full rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
                     />
                   </div>
                 </div>
@@ -1149,7 +1149,7 @@ export function UploadScreen() {
             <button
               type="button"
               onClick={() => fileInputRef.current?.click()}
-              className="mt-4 flex w-full flex-col items-center gap-2 rounded-2xl border-2 border-dashed border-white/70 bg-white/40 px-4 py-10 text-center backdrop-blur-xl transition hover:border-accent-300 hover:bg-white/65 dark:border-white/15 dark:bg-white/[0.05] dark:hover:bg-white/[0.09]"
+              className="mt-4 flex w-full flex-col items-center gap-2 rounded-2xl border-2 border-dashed border-white/70 bg-white/40 px-4 py-10 text-center transition hover:border-accent-300 hover:bg-white/65 dark:border-white/15 dark:bg-white/[0.05] dark:hover:bg-white/[0.09]"
             >
               <span aria-hidden className="animate-float text-frost-500 dark:text-frost-200">
                 <SnowflakeIcon className="size-12" />
@@ -1189,7 +1189,7 @@ export function UploadScreen() {
                   <button
                     type="button"
                     onClick={() => fileInputRef.current?.click()}
-                    className="grid aspect-square w-full place-items-center rounded-2xl border-2 border-dashed border-white/70 text-2xl text-accent-500 backdrop-blur-xl transition hover:border-accent-300 hover:bg-white/60 dark:border-white/15 dark:text-accent-200"
+                    className="grid aspect-square w-full place-items-center rounded-2xl border-2 border-dashed border-white/70 text-2xl text-accent-500 transition hover:border-accent-300 hover:bg-white/60 dark:border-white/15 dark:text-accent-200"
                     aria-label={t("upload.addMorePhotos")}
                   >
                     +
@@ -1204,7 +1204,7 @@ export function UploadScreen() {
               {documents.map((entry) => (
                 <li
                   key={entry.id}
-                  className="flex items-start gap-3 rounded-2xl border border-white/60 bg-white/50 p-3 backdrop-blur-xl dark:border-white/12 dark:bg-white/[0.06]"
+                  className="flex items-start gap-3 rounded-2xl border border-white/60 bg-white/50 p-3 dark:border-white/12 dark:bg-white/[0.06]"
                 >
                   <span className="grid size-10 shrink-0 place-items-center rounded-xl bg-frost-100 text-[10px] font-extrabold uppercase tracking-wide text-frost-700 dark:bg-white/10 dark:text-frost-100">
                     {KIND_LABELS[entry.kind]}
@@ -1300,7 +1300,7 @@ export function UploadScreen() {
               onChange={(event) => setText(event.target.value)}
               rows={4}
               placeholder={t("upload.pastedPlaceholder")}
-              className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
+              className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
             />
           </div>
 
@@ -1313,7 +1313,7 @@ export function UploadScreen() {
               value={focus}
               onChange={(event) => setFocus(event.target.value)}
               placeholder={t("upload.topicPlaceholder")}
-              className="w-full rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
+              className="w-full rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
             />
           </div>
         </section>