Give scrollers a light appearance when the window has a dark appearance so they'll be visible.

sources/PTYScrollView.m

@@ -79,6 +79,14 @@
     }
 }
+- (NSAppearance *)effectiveAppearance {
+    if ([self.window.appearance.name isEqual:NSAppearanceNameVibrantDark]) {
+        return [NSAppearance appearanceNamed:NSAppearanceNameVibrantLight];
+    } else {
+        return [super effectiveAppearance];
+    }
+}
+
 - (BOOL)isLegacyScroller
 {
     return [self scrollerStyle] == NSScrollerStyleLegacy;