Project with referenced nuget package is not able to find files

Question

I have been working on this problem for a while now and was not able to find a solution. I have a Razor-Project, that has - among other files - a Stylesheet.razor file. It looks like that:

<!-- FontAwesome stylesheets -->
<link rel="stylesheet" href="_content/UI.Web.Blazor.Components/UI.Web.Blazor.Components.css" />
<link rel="stylesheet" href="_content/UI.Web.Blazor.Components/assets/fontawesome/css/fontawesome.css" />
<link rel="stylesheet" href="_content/UI.Web.Blazor.Components/assets/fontawesome/css/duotone.css" />
<link rel="stylesheet" href="_content/UI.Web.Blazor.Components/assets/fontawesome/css/solid.css" />
<link rel="stylesheet" href="_content/UI.Web.Blazor.Components/assets/fontawesome/css/brands.css" />

<!-- Telerik scripts -->
<script src="_content/Telerik.UI.for.Blazor/js/telerik-blazor.js" defer></script>

<!-- Custom custom Telerik theme -->
<link rel="stylesheet" href="_content/UI.Web.Blazor.Components/telerik-ui.css" />

The files that are references here are all in the wwwroot-Folder: For example the first href="_content/UI.Web.Blazor.Components/UI.Web.Blazor.Components.css"-File can be found in wwwroot

Then I have a .nuspec file in that same projekt:

<?xml version="1.0" encoding="utf-8"?>
<package xmlns="http://schemas.microsoft.com/packaging/2013/05/nuspec.xsd">
    <metadata>
        <id>UI.Web.Blazor.Components</id>
        <version>1</version>
        <authors>Me</authors>
        <description>A Blazor Component package</description>
        <dependencies>
            <group targetFramework="net8.0">
                <dependency id="Microsoft.AspNetCore.Components.Web" version="8.0.0" />
                <dependency id="Microsoft.Extensions.DependencyInjection" version="8.0.0" />
                <dependency id="Microsoft.Extensions.Localization" version="6.0.7" />
                <dependency id="Telerik.UI.for.Blazor" version="5.0.1" />
            </group>
        </dependencies>
    </metadata>
    <files>
        <file src="bin\Release\net8.0\UI.Web.Blazor.Components.dll" target="lib\net8.0" />
    </files>
</package>

I'm able to build the project and also pack it to a nuget package. So far so good.

But when I include this new package into my other project, where I want to consume it, I get 404-NotFound-Errors for all the files mentioned in the Stylesheet.razor - except the script telerik-blazor.js. That one is from another nuget package and they seem to do it right.

What am I doing wrong? I tried following nuspec changes:

• Including the files via contentFiles-Tag
• Including the files in the files-Tag