Form CSS in Ultimate Member

How to make form field border width to 0. I have been trying lot of code including setting {border:none !important}, but it does not work. My theme provides its own css for form fields, and theme as well as plugin’s css together really look bad
The theme has a horizontal line below the form field, that changes color when clicked, but the border on all 4 sides is the border of ultimate member, i don’t want ultiate member border.

You can see it yourself at https://milyin.com/login.

I added the code written below to additional css of active theme and still everything is still same, i still can see the borders of form, as you can see on url https://milyin.com/login

The grey borders are still visible and i am dying to finish those borders. But i fail. Here is the code i have used.

Besides this the plugin files are all unedited and exact same as available on ww.wp.xz.cn

Besides that the only additional css related to ultimate member that i have been using is

https://docs.ultimatemember.com/article/270-how-to-change-default-ultimate-member-blue-color-using-css

.um-form input[type=text],
.um-form input[type=tel],
.um-form input[type=number],
.um-form input[type=password] {border:none !important}

Please Tell Me Where My Code has been wrong.