How to use props with a CSS helper already in an interpolation?

[jmcannon]

I feel like this should be possible and that I'm getting the syntax wrong. Can someone nudge me in the right direction please?

${props => props.expand && css`
    transform: scale(1.5) translateY(-20px) translateX(${props => props.xOffset} + 'px');
`}

[jmcannon]

I needed to move the closing bracket:

translateX(${props => props.xOffset + 'px'})