Hi how i can put a transparent color in form cells?

Hi how i can put a transparent color in form cells?

I have tried changing the following line of css:

input[type="text"], input[type="email"], input[type="url"], input[type="password"], input[type="search"], input[type="tel"], input[type="number"], textarea {
color: #666666;
background-color: #fafafa; <---------change to transparent>
border-color: #cccccc;

but work in google inspector but dont work wen I refresh the page.