Styling Different for Added Field

I added a telephone # field for my contact form on my website. Even though the coding is exactly the same as the other fields, with </p> and everything, the field box turns out different on the website.

http://www.montrealphotographe.com/en/contact/

As you can probably see, the field box is shorter in height and also a little in length. The border is also a bit thinner. I tried with Firefox, Chrome and Safari and the same thing happens.

Could someone please help me out?

https://ww.wp.xz.cn/plugins/contact-form-7/