Responsive design Adobe DX

I create design for different screen sized, and i use web export to export as HTML file. The file that was exported was sort of static. Like there is a lof of white space on the site when i scale down the page before it reaches the next breakpoint and scales again. I wanted to know how do I make it more fluid. 

Here is what i want it to responds, more fluid (ex):

https://www.dropbox.com/s/fwntjpq1rvnt0qm/Screen%20Recording%202021-01-11%20at%209.57.32%20PM.mov?dl=0

vs how it actually responds, static (ex):

https://www.dropbox.com/s/ugjwb212pqkz4ji/Screen%20Recording%202021-01-11%20at%2010.01.38%20PM.mov?dl=0

Any advice? Thank you!