ET9_WebGL_Dev/Packages/cn.etetet.yooassets/Editor/AssetBundleBuilder/AssetBundleBuilderWindow.uxml

<ui:UXML xmlns:ui="UnityEngine.UIElements" xmlns:uie="UnityEditor.UIElements" xsi="http://www.w3.org/2001/XMLSchema-instance" engine="UnityEngine.UIElements" editor="UnityEditor.UIElements" noNamespaceSchemaLocation="../../UIElementsSchema/UIElements.xsd" editor-extension-mode="True">
    <uie:Toolbar name="Toolbar" style="display: flex; flex-direction: row;" />
    <ui:VisualElement name="Container" />
</ui:UXML>