styling with bootstrap 4

I am using bootstrap 4 in asp.net web site. how to apply bootstrap dropdown style to asp net controls. for example, asp:dropdown.

<asp:dropdown id="ddl" runat="server" /> .

also, when we use  bootstrap classes to create form and inputs , like below. how to add  vertical space between the inputs ?

<div class="form-control">
   <div class="row">
       <div class="col-6>
            <div class="form-group">
                   <asp:textbox id="txt" runat="server">
              </div>
              ,<div class="form-group">
                     <asp:dropdown .....
mikha eAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Julian HansenCommented:
Bootstrap 4 has new classes for padding and spacing see here http://getbootstrap.com/docs/4.1/utilities/spacing/

So to add spacing below your inputs you could do
<div class="form-group mb-1 mt-1"> ...

Open in new window

This will add a top (t) and bottom (b) margin (m) to the element. 1 is 25% of the spacer - which you can define the in SASS spacer map if you don't like the options (1,2,3) provided
Change N (mb-N) to value that matches your requirement in terms of spacing.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
ASP.NET

From novice to tech pro — start learning today.