feat(theme): checkpoint navbar refraction surface

src/components/theme/GlassNavbarRefractionDefs.vue

@@ -1,35 +1,77 @@
 <script lang="ts" setup>
-const displacementMapMarkup = `
-  <svg viewBox="0 0 1200 80" xmlns="http://www.w3.org/2000/svg">
-    <defs>
-      <linearGradient id="x" x1="0%" y1="0%" x2="100%" y2="0%">
-        <stop offset="0%" stop-color="rgb(24 128 0)" />
-        <stop offset="8%" stop-color="rgb(128 128 0)" />
-        <stop offset="92%" stop-color="rgb(128 128 0)" />
-        <stop offset="100%" stop-color="rgb(232 128 0)" />
-      </linearGradient>
-      <linearGradient id="y" x1="0%" y1="0%" x2="0%" y2="100%">
-        <stop offset="0%" stop-color="rgb(0 0 28)" />
-        <stop offset="18%" stop-color="rgb(0 0 128)" />
-        <stop offset="82%" stop-color="rgb(0 0 128)" />
-        <stop offset="100%" stop-color="rgb(0 0 228)" />
-      </linearGradient>
-    </defs>
-    <rect width="1200" height="80" rx="20" fill="black" />
-    <rect width="1200" height="80" rx="20" fill="url(#x)" />
-    <rect width="1200" height="80" rx="20" fill="url(#y)" style="mix-blend-mode: screen" />
-    <rect
-      x="10"
-      y="10"
-      width="1180"
-      height="60"
-      rx="14"
-      fill="rgb(128 128 128)"
-      style="filter: blur(8px)"
-    />
-  </svg>
-`
-const displacementMapUrl = `data:image/svg+xml,${encodeURIComponent(displacementMapMarkup)}`
+import { createGlassNavbarDisplacementMap, NEUTRAL_GLASS_NAVBAR_DISPLACEMENT_MAP } from '@/utils/glassNavbarRefraction'
+
+const DEFAULT_NAVBAR_GEOMETRY = {
+  height: 64,
+  radius: 16,
+  width: 1200,
+}
+const MAP_RESIZE_SETTLE_MS = 180
+const displacementMapUrl = ref(NEUTRAL_GLASS_NAVBAR_DISPLACEMENT_MAP)
+const displacementMapSize = reactive({
+  height: DEFAULT_NAVBAR_GEOMETRY.height,
+  width: DEFAULT_NAVBAR_GEOMETRY.width,
+})
+
+let observedNavbar: HTMLElement | null = null
+let resizeObserver: ResizeObserver | null = null
+let resizeTimer: ReturnType<typeof setTimeout> | null = null
+
+function syncDisplacementMap() {
+  if (!observedNavbar) return
+
+  const bounds = observedNavbar.getBoundingClientRect()
+  const styles = getComputedStyle(observedNavbar)
+  const floatingRadius = Number.parseFloat(styles.getPropertyValue('--shell-floating-navbar-radius'))
+  const borderRadius = Number.parseFloat(styles.borderStartStartRadius)
+  const height = Math.max(1, Math.round(bounds.height))
+  const width = Math.max(1, Math.round(bounds.width))
+
+  displacementMapSize.height = height
+  displacementMapSize.width = width
+  displacementMapUrl.value = createGlassNavbarDisplacementMap({
+    height,
+    radius: Number.isFinite(floatingRadius)
+      ? floatingRadius
+      : Number.isFinite(borderRadius)
+        ? borderRadius
+        : DEFAULT_NAVBAR_GEOMETRY.radius,
+    width,
+  })
+}
+
+// 几何动画期间沿用上一张位移图，尺寸稳定后再重建，避免逐帧生成并上传位移纹理。
+function scheduleDisplacementMapSync() {
+  if (resizeTimer !== null) clearTimeout(resizeTimer)
+  resizeTimer = setTimeout(() => {
+    resizeTimer = null
+    syncDisplacementMap()
+  }, MAP_RESIZE_SETTLE_MS)
+}
+
+onMounted(() => {
+  observedNavbar = document.querySelector('.layout-wrapper[data-glass-navbar-refraction="chromium"] .layout-navbar')
+  if (!observedNavbar) return
+
+  syncDisplacementMap()
+  if (typeof ResizeObserver === 'undefined') {
+    window.addEventListener('resize', scheduleDisplacementMapSync, { passive: true })
+
+    return
+  }
+
+  resizeObserver = new ResizeObserver(scheduleDisplacementMapSync)
+  resizeObserver.observe(observedNavbar)
+})
+
+onBeforeUnmount(() => {
+  if (resizeTimer !== null) clearTimeout(resizeTimer)
+  resizeTimer = null
+  resizeObserver?.disconnect()
+  resizeObserver = null
+  window.removeEventListener('resize', scheduleDisplacementMapSync)
+  observedNavbar = null
+})
 </script>
 
 <template>
@@ -46,8 +88,8 @@ const displacementMapUrl = `data:image/svg+xml,${encodeURIComponent(displacement
         <feImage
           x="0"
           y="0"
-          width="100%"
-          height="100%"
+          :width="displacementMapSize.width"
+          :height="displacementMapSize.height"
           preserveAspectRatio="none"
           :href="displacementMapUrl"
           result="map"
@@ -66,8 +108,8 @@ const displacementMapUrl = `data:image/svg+xml,${encodeURIComponent(displacement
         <feImage
           x="0"
           y="0"
-          width="100%"
-          height="100%"
+          :width="displacementMapSize.width"
+          :height="displacementMapSize.height"
           preserveAspectRatio="none"
           :href="displacementMapUrl"
           result="map"

src/styles/__tests__/glassOverlayMaterial.spec.ts

@@ -395,6 +395,8 @@ describe('glass overlay material styles', () => {
 
   it('scopes live navbar refraction to Chromium clear and tinted floating shells', () => {
     const styles = readFileSync(resolve(cwd(), 'src/styles/themes/glass.scss'), 'utf8')
+    const filterDefinitions = readFileSync(resolve(cwd(), 'src/components/theme/GlassNavbarRefractionDefs.vue'), 'utf8')
+    const refractionUtilities = readFileSync(resolve(cwd(), 'src/utils/glassNavbarRefraction.ts'), 'utf8')
 
     expect(styles).toContain("data-glass-navbar-refraction='chromium'")
     expect(styles).toContain("url('#glass-navbar-live-refraction-balanced')")
@@ -402,6 +404,63 @@ describe('glass overlay material styles', () => {
     expect(styles).toMatch(
       /:is\(\[data-glass-appearance='clear'\], \[data-glass-appearance='tinted'\]\)[\s\S]*?\.layout-navbar-floating-eligible\.layout-navbar-away-from-top[\s\S]*?\.layout-navbar/,
     )
+    expect(styles).toContain('inline-size: auto !important')
+    expect(styles).toContain('inset-block-start: 0 !important')
+    expect(styles).toContain('inset-inline: 0 !important')
+    expect(styles).toContain('inset-block-start: var(--shell-floating-navbar-inset) !important')
+    expect(styles).toContain('inset-inline: var(--shell-floating-navbar-inset) !important')
+    expect(styles).toContain('transform: none !important')
+    expect(styles).toContain(
+      'inset-block-start var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing)',
+    )
+    expect(styles).toContain(
+      'inset-inline-end var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing)',
+    )
+    expect(styles).toContain(
+      'inset-inline-start var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing)',
+    )
+    const highQualityStart = styles.indexOf("html[data-theme='glass'][data-glass-quality='high']")
+    const liveRefractionStart = styles.lastIndexOf(
+      "html[data-theme='glass']:is([data-glass-appearance='clear'], [data-glass-appearance='tinted'])",
+      highQualityStart,
+    )
+    const liveRefractionRule = styles.slice(liveRefractionStart, highQualityStart)
+
+    expect(liveRefractionStart).toBeGreaterThanOrEqual(0)
+    expect(highQualityStart).toBeGreaterThan(liveRefractionStart)
+    expect(liveRefractionRule).toContain("backdrop-filter: url('#glass-navbar-live-refraction-balanced')")
+    expect(liveRefractionRule).toContain('border: 0 !important')
+    expect(liveRefractionRule).toContain('linear-gradient(145deg, rgba(255, 255, 255, 0.13), transparent 34%)')
+    expect(liveRefractionRule).not.toContain('inset 0 1px 0 rgba(255, 255, 255, 0.4)')
+    expect(styles).toContain('inline-size: min(100vw, variables.$layout-boxed-content-width)')
+    expect(styles).toContain('transform: translateX(-50%) !important')
+    expect(styles).toMatch(
+      /\[data-glass-appearance='tinted'\][\s\S]*?\.layout-navbar\s*\{[\s\S]*?--glass-material-accent-rgb/,
+    )
+    expect(liveRefractionRule).not.toContain('&::before')
+    expect(styles).not.toContain('&::after')
     expect(styles).not.toContain("[data-glass-appearance='frosted'][data-glass-navbar-refraction='chromium']")
+    expect(filterDefinitions).toContain('createGlassNavbarDisplacementMap')
+    expect(filterDefinitions).toContain('NEUTRAL_GLASS_NAVBAR_DISPLACEMENT_MAP')
+    expect(filterDefinitions).toContain('getBoundingClientRect()')
+    expect(filterDefinitions).toContain('new ResizeObserver(scheduleDisplacementMapSync)')
+    expect(filterDefinitions).toContain('in2="map"')
+    expect(filterDefinitions).toContain(':width="displacementMapSize.width"')
+    expect(filterDefinitions).toContain(':height="displacementMapSize.height"')
+    expect(filterDefinitions).not.toContain('width="100%"')
+    expect(filterDefinitions).not.toContain('height="100%"')
+    expect(filterDefinitions).toContain('scale="-22"')
+    expect(filterDefinitions).toContain('scale="-34"')
+    expect(filterDefinitions).toContain('x="-8%"')
+    expect(filterDefinitions).toContain('width="116%"')
+    expect(filterDefinitions).toContain('x="-12%"')
+    expect(filterDefinitions).toContain('width="124%"')
+    expect(filterDefinitions).not.toContain('horizontal-continuity')
+    expect(filterDefinitions).not.toContain('<feComposite')
+    expect(filterDefinitions).not.toContain('<feGaussianBlur')
+    expect(refractionUtilities).toContain('createGlassNavbarDisplacementField')
+    expect(refractionUtilities).toContain('OUTER_NEUTRAL_GUARD_PX')
+    expect(refractionUtilities).toContain('Math.sin(Math.PI * normalizedDistance)')
+    expect(refractionUtilities).toContain("canvas.toDataURL('image/png')")
   })
 })

src/styles/themes/glass.scss

@@ -1652,57 +1652,70 @@ html[data-theme='glass'] body[data-theme='glass'] .native-login-field:focus-with
   }
 }
 
-// Chromium 直接位移浏览器已合成的下层内容；其他引擎保留稳定的基础顶栏材质。
+// 实时折射表面在贴顶与浮动状态使用同一布局坐标系，只插值真实 inset，避免切换 transform 采样空间。
 html[data-theme='glass']:is([data-glass-appearance='clear'], [data-glass-appearance='tinted'])
   body[data-theme='glass']
-  .layout-wrapper[data-glass-navbar-refraction='chromium'].layout-navbar-floating-eligible.layout-navbar-away-from-top
+  .layout-wrapper[data-glass-navbar-refraction='chromium'].layout-navbar-floating-eligible
   .layout-navbar {
-  -webkit-backdrop-filter: none !important;
-  backdrop-filter: none !important;
-  background-color: transparent !important;
-  background-image: none !important;
-
-  &::before {
-    position: absolute;
-    z-index: 0;
-    border: 1px solid rgba(255, 255, 255, 0.24);
-    border-radius: inherit;
-    -webkit-backdrop-filter: blur(1.5px) saturate(118%);
-    backdrop-filter: url('#glass-navbar-live-refraction-balanced') blur(1.5px) saturate(118%);
-    background:
-      linear-gradient(145deg, rgba(255, 255, 255, 0.13), transparent 34%),
-      linear-gradient(rgba(7, 14, 25, 0.06), rgba(7, 14, 25, 0.13));
-    box-shadow:
-      inset 0 1px 0 rgba(255, 255, 255, 0.4),
-      inset 0 -1px 0 rgba(4, 10, 20, 0.22),
-      0 12px 32px rgba(3, 7, 18, 0.16);
-    content: '';
-    inset: 0;
-    pointer-events: none;
-  }
+  inline-size: auto !important;
+  inset-block-start: 0 !important;
+  inset-inline: 0 !important;
+  transform: none !important;
+  transition:
+    background-color var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing),
+    border-color var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing),
+    border-radius var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing),
+    box-shadow var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing),
+    inset-block-start var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing),
+    inset-inline-end var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing),
+    inset-inline-start var(--shell-floating-navbar-motion-duration) var(--shell-floating-navbar-motion-easing) !important;
 
   .navbar-content-container {
     position: relative;
     z-index: 1;
+    // 外壳内收时，导航内容仍按视口中心对齐，避免控件位置跟随采样面的宽度变化。
+    inline-size: min(100vw, variables.$layout-boxed-content-width);
+    inset-inline-start: 50%;
+    transform: translateX(-50%) !important;
   }
 }
 
+// 位移、材质和轮廓由同一个真实尺寸的表面完成；顶部不叠加硬高光线。
+html[data-theme='glass']:is([data-glass-appearance='clear'], [data-glass-appearance='tinted'])
+  body[data-theme='glass']
+  .layout-wrapper[data-glass-navbar-refraction='chromium'].layout-navbar-floating-eligible.layout-navbar-away-from-top
+  .layout-navbar {
+  border: 0 !important;
+  -webkit-backdrop-filter: blur(1.5px) saturate(118%) !important;
+  backdrop-filter: url('#glass-navbar-live-refraction-balanced') blur(1.5px) saturate(118%) !important;
+  background:
+    linear-gradient(145deg, rgba(255, 255, 255, 0.13), transparent 34%),
+    linear-gradient(rgba(7, 14, 25, 0.06), rgba(7, 14, 25, 0.13)) !important;
+  box-shadow:
+    inset 1px 0 0 rgba(255, 255, 255, 0.2),
+    inset -1px 0 0 rgba(255, 255, 255, 0.16),
+    inset 0 -1px 0 rgba(4, 10, 20, 0.22),
+    0 12px 32px rgba(3, 7, 18, 0.16) !important;
+  inset-block-start: var(--shell-floating-navbar-inset) !important;
+  inset-inline: var(--shell-floating-navbar-inset) !important;
+}
+
 html[data-theme='glass'][data-glass-quality='high']:is(
     [data-glass-appearance='clear'],
     [data-glass-appearance='tinted']
   )
   body[data-theme='glass']
   .layout-wrapper[data-glass-navbar-refraction='chromium'].layout-navbar-floating-eligible.layout-navbar-away-from-top
-  .layout-navbar::before {
-  backdrop-filter: url('#glass-navbar-live-refraction-high') blur(1px) saturate(122%);
+  .layout-navbar {
+  backdrop-filter: url('#glass-navbar-live-refraction-high') blur(1px) saturate(122%) !important;
 }
 
 html[data-theme='glass'][data-glass-appearance='tinted']
   body[data-theme='glass']
   .layout-wrapper[data-glass-navbar-refraction='chromium'].layout-navbar-floating-eligible.layout-navbar-away-from-top
-  .layout-navbar::before {
+  .layout-navbar {
   background:
     linear-gradient(145deg, rgba(255, 255, 255, 0.14), transparent 36%),
     linear-gradient(rgba(var(--glass-material-accent-rgb), 0.09), rgba(var(--glass-material-accent-rgb), 0.035)),
-    linear-gradient(rgba(7, 14, 25, 0.08), rgba(7, 14, 25, 0.15));
+    linear-gradient(rgba(7, 14, 25, 0.08), rgba(7, 14, 25, 0.15)) !important;
 }

src/utils/__tests__/glassNavbarRefraction.spec.ts

@@ -1,5 +1,34 @@
 import { describe, expect, it } from 'vitest'
-import { supportsGlassNavbarLiveRefraction } from '@/utils/glassNavbarRefraction'
+import { createGlassNavbarDisplacementField, supportsGlassNavbarLiveRefraction } from '@/utils/glassNavbarRefraction'
+
+describe('createGlassNavbarDisplacementField', () => {
+  function pixelAt(field: ReturnType<typeof createGlassNavbarDisplacementField>, x: number, y: number) {
+    const offset = (y * field.width + x) * 4
+
+    return [...field.pixels.slice(offset, offset + 4)]
+  }
+
+  it('keeps both contour boundary and interior neutral while bending only the narrow rim', () => {
+    const field = createGlassNavbarDisplacementField({ height: 41, radius: 12, width: 101 })
+
+    expect(field.width).toBe(101)
+    expect(field.height).toBe(41)
+    expect(pixelAt(field, 50, 0)).toEqual([128, 128, 128, 255])
+    expect(pixelAt(field, 50, 20)).toEqual([128, 128, 128, 255])
+    expect(pixelAt(field, 50, 5)[2]).toBeLessThan(64)
+    expect(pixelAt(field, 5, 20)[0]).toBeLessThan(64)
+    expect(pixelAt(field, 95, 20)[0]).toBeGreaterThan(192)
+    expect(pixelAt(field, 50, 35)[2]).toBeGreaterThan(192)
+  })
+
+  it('clamps invalidly small geometry to a renderable pixel surface', () => {
+    const field = createGlassNavbarDisplacementField({ height: 0, radius: 20, width: -10 })
+
+    expect(field.width).toBe(1)
+    expect(field.height).toBe(1)
+    expect([...field.pixels]).toEqual([128, 128, 128, 255])
+  })
+})
 
 describe('supportsGlassNavbarLiveRefraction', () => {
   it('enables the verified Chromium engine path for Chrome and Edge', () => {

src/utils/glassNavbarRefraction.ts

@@ -9,6 +9,124 @@ export interface GlassNavbarRefractionBrowserIdentity {
   userAgent: string
 }
 
+export interface GlassNavbarDisplacementGeometry {
+  /** 折射表面的实际 CSS 像素高度。 */
+  height: number
+  /** 最终可见外轮廓的圆角半径。 */
+  radius: number
+  /** 折射表面的实际 CSS 像素宽度。 */
+  width: number
+}
+
+export interface GlassNavbarDisplacementField {
+  /** 位移图的 CSS 像素高度。 */
+  height: number
+  /** 按 RGBA 顺序存储的非预乘像素通道。 */
+  pixels: Uint8ClampedArray
+  /** 位移图的 CSS 像素宽度。 */
+  width: number
+}
+
+export const NEUTRAL_GLASS_NAVBAR_DISPLACEMENT_MAP =
+  'data:image/svg+xml,%3Csvg xmlns="http://www.w3.org/2000/svg" width="1" height="1"%3E%3Cpath fill="%23808080" d="M0 0h1v1H0z"/%3E%3C/svg%3E'
+
+const DISPLACEMENT_NEUTRAL_CHANNEL = 128
+const DISPLACEMENT_CHANNEL_AMPLITUDE = 127
+const OUTER_NEUTRAL_GUARD_PX = 2
+const REFRACTION_BAND_PX = 12
+const REFRACTION_PROFILE_POWER = 2
+
+function normalizePixelSize(value: number) {
+  return Number.isFinite(value) ? Math.max(1, Math.round(value)) : 1
+}
+
+function roundedRectangleSignedDistance(x: number, y: number, width: number, height: number, radius: number) {
+  const offsetX = Math.abs(x - width / 2) - (width / 2 - radius)
+  const offsetY = Math.abs(y - height / 2) - (height / 2 - radius)
+  const outsideX = Math.max(offsetX, 0)
+  const outsideY = Math.max(offsetY, 0)
+
+  return Math.hypot(outsideX, outsideY) + Math.min(Math.max(offsetX, offsetY), 0) - radius
+}
+
+function clampChannel(value: number) {
+  return Math.max(0, Math.min(255, Math.round(value)))
+}
+
+/**
+ * 生成圆角表面的法线位移场。
+ * 外轮廓和内区都保持中性采样，避免折射在裁剪边界或主体内容区形成整带错位。
+ */
+export function createGlassNavbarDisplacementField({
+  height,
+  radius,
+  width,
+}: GlassNavbarDisplacementGeometry): GlassNavbarDisplacementField {
+  const pixelWidth = normalizePixelSize(width)
+  const pixelHeight = normalizePixelSize(height)
+  const maxRadius = Math.min(pixelWidth, pixelHeight) / 2
+  const pixelRadius = Number.isFinite(radius) ? Math.max(0, Math.min(maxRadius, radius)) : 0
+  const bandWidth = Math.min(REFRACTION_BAND_PX, Math.min(pixelWidth, pixelHeight) / 2)
+  const outerGuard = Math.min(OUTER_NEUTRAL_GUARD_PX, bandWidth / 4)
+  const pixels = new Uint8ClampedArray(pixelWidth * pixelHeight * 4)
+
+  for (let offset = 0; offset < pixels.length; offset += 4) {
+    pixels[offset] = DISPLACEMENT_NEUTRAL_CHANNEL
+    pixels[offset + 1] = DISPLACEMENT_NEUTRAL_CHANNEL
+    pixels[offset + 2] = DISPLACEMENT_NEUTRAL_CHANNEL
+    pixels[offset + 3] = 255
+  }
+
+  for (let y = 0; y < pixelHeight; y += 1) {
+    for (let x = 0; x < pixelWidth; x += 1) {
+      const sampleX = x + 0.5
+      const sampleY = y + 0.5
+      const signedDistance = roundedRectangleSignedDistance(sampleX, sampleY, pixelWidth, pixelHeight, pixelRadius)
+      const distanceInside = -signedDistance
+
+      if (signedDistance > 0 || distanceInside <= outerGuard || distanceInside >= bandWidth) continue
+
+      const normalizedDistance = (distanceInside - outerGuard) / (bandWidth - outerGuard)
+      const profile = Math.sin(Math.PI * normalizedDistance) ** REFRACTION_PROFILE_POWER
+      const gradientX =
+        roundedRectangleSignedDistance(sampleX + 0.5, sampleY, pixelWidth, pixelHeight, pixelRadius) -
+        roundedRectangleSignedDistance(sampleX - 0.5, sampleY, pixelWidth, pixelHeight, pixelRadius)
+      const gradientY =
+        roundedRectangleSignedDistance(sampleX, sampleY + 0.5, pixelWidth, pixelHeight, pixelRadius) -
+        roundedRectangleSignedDistance(sampleX, sampleY - 0.5, pixelWidth, pixelHeight, pixelRadius)
+      const gradientLength = Math.hypot(gradientX, gradientY) || 1
+      const offset = (y * pixelWidth + x) * 4
+
+      pixels[offset] = clampChannel(
+        DISPLACEMENT_NEUTRAL_CHANNEL + (DISPLACEMENT_CHANNEL_AMPLITUDE * gradientX * profile) / gradientLength,
+      )
+      pixels[offset + 2] = clampChannel(
+        DISPLACEMENT_NEUTRAL_CHANNEL + (DISPLACEMENT_CHANNEL_AMPLITUDE * gradientY * profile) / gradientLength,
+      )
+    }
+  }
+
+  return { height: pixelHeight, pixels, width: pixelWidth }
+}
+
+/** 把位移场栅格化为浏览器可直接加载的无损 PNG。 */
+export function createGlassNavbarDisplacementMap(geometry: GlassNavbarDisplacementGeometry) {
+  const field = createGlassNavbarDisplacementField(geometry)
+  const canvas = document.createElement('canvas')
+  const context = canvas.getContext('2d')
+
+  if (!context) return NEUTRAL_GLASS_NAVBAR_DISPLACEMENT_MAP
+
+  canvas.width = field.width
+  canvas.height = field.height
+  const imageData = context.createImageData(field.width, field.height)
+
+  imageData.data.set(field.pixels)
+  context.putImageData(imageData, 0, 0)
+
+  return canvas.toDataURL('image/png')
+}
+
 /** 仅在已验证 SVG backdrop 位移的 Chromium 引擎启用实时顶栏折射。 */
 export function supportsGlassNavbarLiveRefraction(browserIdentity: GlassNavbarRefractionBrowserIdentity = navigator) {
   const brands = browserIdentity.userAgentData?.brands