Hi Christiangerdes,
You can do this with yield and sections
app.blade.php
<!DOCTYPE html>
<html lang="da">
<head>
<meta name="csrf-token" value="{{ csrf_token() }}">
@yield('css', 'default_css_if_no_css_is_given.css')
</head>
<body>
<div id="app">
login-template.
<template>
<div id="app-basic">
<router-view></router-view>
</div>
</template>
@section('css')
<style src="logincss.css"></style>
@endsection