A responsive order summary card made with CSS Flexbox

I couldn't provide the correct box shadow to the main card and the button. Please help me figuring out.

Also, I am confused about the typography. The style-guide.md says the paragraph should be 16px but that almost never works, it looks too big. My screen resolution is 1024x768. I have to set it back to 11.3px. Also the letter spacing and word spacing displayed in the design files is quite less. And I couldn't adjust my design according to that.