Inline variables in Blade template

I want to include theme stylesheet into Blade template. Unfortunately, code attached finishes with syntax error. What’s wrong?

    <!-- Theme setup -->
    @php
        $theme = sprintf("css/themes/%s.css", config('app.dm.theme'));
        //error_log($theme);
    @endphp
    <link rel="stylesheet" href="') }}">

via Chebli Mohamed