List box width too big when viewing on mobile

I have a drop down list box on my form which looks fine when viewing my website on computer however the width is far too big when viewing on mobile. 

I have tried using the following code under the @media screen codes however it doesn't seem to be any smaller.

    #input_171 {

        width : 50px;

    }

What am i doing wrong and can this list box width be made smaller for when viewing on mobile devices?

My webpage the form is on is http://www.predictwrestling.com/abcd

Hello,

Your CSS code is correct, but there are statements that overrides your code. Please add !important at the end of your form. Your code should be:

#input_171 {

        width : 50px !impoartant;

 }

I hope this answer helps. Please don't hesitate to contact us for your further queries.

All the best!