我为空div上的背景图片设置了以下代码，但没有响应。我不想设置固定高度。还有其他方法吗？
$ Update-Module -Name Az
WARNING: Unable to resolve package source 'https://www.powershellgallery.com/api/v2'.
PackageManagement\Install-Package : No match was found for the specified search criteria and module name 'Az'. Try
Get-PSRepository to see all available registered module repositories.
At C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\1.0.0.1\PSModule.psm1:2089 char:20
+ ... $sid = PackageManagement\Install-Package @PSBoundParameters
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Microsoft.Power....InstallPackage:InstallPackage) [Install-Package], Ex
ception
+ FullyQualifiedErrorId : NoMatchFoundForCriteria,Microsoft.PowerShell.PackageManagement.Cmdlets.InstallPackage