In desktop it looks very good, simple, neat and great.
It’s weird, but as I tried responsive functionality using chrome dev tool it failed, but firefox worked. Make sure the layout is responsive and compatible for all browsers.
Good parts:
placeholder for text fields and textarea, very good.
using titled border to split sections in form, very good.
radio and checkbox buttons with associated label, cool.
Great contrast between fg and bg, very good.
You may add one disable hidden and selected option for combobox to have a non valid default value when page is load.
One thing could make the layout and page a little mess is about titled border in small screens. becasue the title text is a little too much, floating text to next line make it a little mess, check:
adding a little more space between elements, and less margin/padding space from screen edge could make the form a little easier to read, same giving more space for content.
You may also check my survey form challenge walkthrough (feedback is appreciated) and check the subjects there too, hope they help.
Very good design I believe, keep going on great work, happy programming.