How to make plotly graph reactive when using htmlwidgets::saveWidget()

As the above says.

Im converting a chart to html using html widgets. The chart has been developed with specific proportions as it overlays some annotations on a polar scale. When I render it, it currently has dimensions set when the chart is initially built using plot_ly(width = 1000, height = 700). If I set width to 100% the chart no longer behaves. But I know if I take an SVG render of the plot, I can change its width to 100% and it will dynamically scale.

How can I achieve the same with the htmlwidgets? How can I make my chart render a dynamic svg?