Webflow form issue

Hello,

I’m trying to change the Hover colour on the input field of a contact form but when I go to make the field darker it does not fill the whole area but seems to stop around the place holder text, making it look like a border. Does anyone know why the whole input field it not darkening?

(just using the dark grey as an example)

https://preview.webflow.com/preview/kaylas-amazing-site-2dffe1?utm_medium=preview_link&utm_source=designer&utm_content=kaylas-amazing-site-2dffe1&preview=27957d24c665116f259be71b408b449a&pageId=62ef9e7117fa6304a8a68f67&workflow=preview