how to specify background url for CSS using kotlin dsl

Question

I want to load the background from a local file in the project using Kotlin dsl for css, and the original css file snippet looks like this:

body {
    margin: 50;
    background: url("banana.png") repeat 0 0;
    animation: animate 15s infinite;
    animation-timing-function: linear;
}

here is what I've tried in my kotlin script that didn't work:

body {
    background = "url(\"/assets/banana.png\");"
    backgroundRepeat = BackgroundRepeat.repeat
    animationTimingFunction = Timing.linear
}

and I have put the banana.png file in the resources/static folder in my module and also added this code in my routings:

static(remotePath = "assets") {
    resources("static")
}

even when I use the styles.css file, it only works when I'm in the base route, and in subroutes the css file couldn't show the background.