We are in the process of converting to Lightning  and have tried adding lightningStylesheets="true" to the <apex:page> tag in a couple of our Visualforce pages (Beta feature in Winter '18 Release) to see if we can use a minimalist approach to our initial conversion.  In general this seems to work well if the display is large enough to display all fields.  When the browser screen is made smaller, the fields remain the same size and a scrollbar appears.  If we don't add this tag and view the page in Lightning, the fields get smaller so it all fits in the browser window without scrolling.  Is there something we can add to the VF page to get it to adjust the sizes with the window size?