ext_conf_template.txt

# https://docs.typo3.org/m/typo3/reference-coreapi/main/en-us/ExtensionArchitecture/FileStructure/ExtConfTemplate.html

backend {
    # cat=Overrides; type=string; label=LLL:EXT:backend/Resources/Private/Language/locallang.xlf:config.loginLogo
    loginLogo = EXT:sitepackage/Resources/Public/Icons/Extension.svg

    # cat=Overrides; type=string; label=LLL:EXT:backend/Resources/Private/Language/locallang.xlf:config.loginLogoAlt
    loginLogoAlt = Login Logo alternative Text

    # cat=Overrides; type=color; label=LLL:EXT:backend/Resources/Private/Language/locallang.xlf:config.loginHighlightColor
    loginHighlightColor = #ff8700

    # cat=Overrides; type=string; label=LLL:EXT:backend/Resources/Private/Language/locallang.xlf:config.loginBackgroundImage
    loginBackgroundImage = EXT:sitepackage/Resources/Public/Images/Backend/loginBackgroundImage.svg

    # cat=Overrides; type=string; label=LLL:EXT:backend/Resources/Private/Language/locallang.xlf:config.loginFootnote
    loginFootnote = © %s Sitepackage

    # cat=Overrides; type=string; label=LLL:EXT:backend/Resources/Private/Language/locallang.xlf:config.backendLogo
    backendLogo = EXT:sitepackage/Resources/Public/Icons/Extension.svg

    # cat=Overrides; type=string; label=LLL:EXT:backend/Resources/Private/Language/locallang.xlf:config.backendFavicon
    backendFavicon = EXT:sitepackage/Resources/Public/Icons/Extension.svg
}