Brackets

How would I write the following in STSS?

'.gradient-top-left': {
    backgroundGradient: {
        type: 'radial',
        startPoint: {
            x: 50,
            y: 50
        },
        endPoint: {
            x: 50,
            y: 50
        },
        colors: ['red', 'blue'],
        startRadius: '100%',
        endRadius: 0,
        backfillStart: true
    }
},
