@a_goer,

Please stop searching of overwriting issues, that CSS is located in core and that is the original CSS. The overwriting CSS are the custom CSS you're adding to fix conflicts.

Please add all new CSS code below others not on top others.

I moved the code as requested. Thw button is still cut down in mobile view. Any suggestions? Thank you for helping me with this.

You'll not see the difference in mobile. Mobile browser cache is very hard. You should use other phones or browsers which have never opened your website. And please leave some URL to your website.