Hi,
After a fresh install of rStudio an running the default (tutorial) application of shiny shown here :
https://shiny.rstudio.com/tutorial/written-tutorial/lesson1/
It is not rendering as the example... No loayout, no CSSn and no interactivity... 
Surely missing something (library / package) but I can't figure out what is missing... This is the output of the console...
> install.packages("shiny")
Installing package into ‘C:/Users/Stéphane/Documents/R/win-library/3.6’
(as ‘lib’ is unspecified)
trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.6/shiny_1.3.2.zip'
Content type 'application/zip' length 4694584 bytes (4.5 MB)
downloaded 4.5 MB
package ‘shiny’ successfully unpacked and MD5 sums checked
The downloaded binary packages are in
C:\Users\Stéphane\AppData\Local\Temp\Rtmpk3JPk5\downloaded_packages
> library(shiny)
> runExample("01_hello")
Listening on http://127.0.0.1:7507
Thank you for helping !