Fix sub-pixel rendering mismatch in selector-dynamicPseudoElement test

Set explicit width on the App container to avoid fractional pixel widths
that cause 1px screenshot differences between the side-by-side panels.
Text rendering at the button's UA font size (13.3333px) produces
sub-pixel widths that sum to 539.9375px — the rounding differs between
the input and output panels due to their different page positions.

Co-authored-by: Kenneth Skovhus <skovhus@users.noreply.github.com>

Author: cursoragent

test-cases/selector-dynamicPseudoElement.input.tsx

@@ -55,7 +55,7 @@ const Button = styled.button<{ $glowColor: string }>`
 `;
 
 export const App = () => (
-  <div style={{ display: "flex", gap: "16px", padding: "16px" }}>
+  <div style={{ display: "flex", gap: "16px", padding: "16px", width: 560 }}>
     <Badge $badgeColor="red">Notification</Badge>
     <Badge $badgeColor="green">Online</Badge>
     <Badge $badgeColor="blue">Info</Badge>

test-cases/selector-dynamicPseudoElement.output.tsx

@@ -44,7 +44,7 @@ function Button(props: ButtonProps) {
 }
 
 export const App = () => (
-  <div style={{ display: "flex", gap: "16px", padding: "16px" }}>
+  <div style={{ display: "flex", gap: "16px", padding: "16px", width: 560 }}>
     <Badge badgeColor="red">Notification</Badge>
     <Badge badgeColor="green">Online</Badge>
     <Badge badgeColor="blue">Info</Badge>