add glassy effect to headers

src/components/Layout/Header/GlassyBackdrop.tsx

@@ -0,0 +1,13 @@
+import {View} from 'react-native'
+
+import {atoms as a, useTheme} from '#/alf'
+
+/**
+ * GlassyBackdrop component
+ * On web, it applies a backdrop filter to create a glassy effect.
+ * On native and non-safari mobile web, it's just a solid color.
+ */
+export function GlassyBackdrop() {
+  const t = useTheme()
+  return <View style={[a.absolute, a.inset_0, t.atoms.bg]} />
+}

src/components/Layout/Header/GlassyBackdrop.web.tsx

@@ -0,0 +1,31 @@
+import {View} from 'react-native'
+
+import {isAndroidWeb} from '#/lib/browser'
+import {atoms as a, useTheme} from '#/alf'
+
+/**
+ * GlassyBackdrop component
+ * On web, it applies a backdrop filter to create a glassy effect.
+ * On native and non-safari mobile web, it's just a solid color.
+ */
+export function GlassyBackdrop() {
+  const t = useTheme()
+
+  if (isAndroidWeb) {
+    return <View style={[a.absolute, a.inset_0, t.atoms.bg]} />
+  }
+
+  return (
+    <>
+      <View style={[a.absolute, a.inset_0, t.atoms.bg, {opacity: 0.9}]} />
+      <View
+        style={[
+          a.absolute,
+          a.inset_0,
+          a.pointer_events_none,
+          {backdropFilter: 'blur(16px)'},
+        ]}
+      />
+    </>
+  )
+}

src/components/Layout/Header/index.tsx

@@ -29,6 +29,7 @@ import {
 } from '#/components/Layout/const'
 import {ScrollbarOffsetContext} from '#/components/Layout/context'
 import {Text} from '#/components/Typography'
+import {GlassyBackdrop} from './GlassyBackdrop'
 
 export function Outer({
   children,
@@ -56,7 +57,7 @@ export function Outer({
         a.flex_row,
         a.align_center,
         a.gap_sm,
-        sticky && web([a.sticky, {top: 0}, a.z_10, t.atoms.bg]),
+        sticky && web([a.sticky, {top: 0}, a.z_10]),
         gutters,
         platform({
           native: [a.pb_xs, {minHeight: 48}],
@@ -71,6 +72,7 @@ export function Outer({
           ],
         },
       ]}>
+      {sticky && <GlassyBackdrop />}
       {children}
     </View>
   )
@@ -131,11 +133,7 @@ export function BackButton({onPress, style, ...props}: Partial<ButtonProps>) {
         shape="square"
         onPress={onPressBack}
         hitSlop={HITSLOP_30}
-        style={[
-          {marginLeft: -BUTTON_VISUAL_ALIGNMENT_OFFSET},
-          a.bg_transparent,
-          style,
-        ]}
+        style={[{marginLeft: -BUTTON_VISUAL_ALIGNMENT_OFFSET}, style]}
         {...props}>
         <ButtonIcon icon={ArrowLeft} size="lg" />
       </Button>