Fix input field CSS for dark mode on login/signup pages

[1Burhanuddin]

Problem

The input fields on the login and signup pages have incorrect CSS styling in dark mode. A different background color is visible behind the label, creating a visual inconsistency.

Expected Behavior

Input field labels should have proper background styling in dark mode, similar to how they appear in light mode.

Reference Implementation

The employee list page has the proper implementation of input field styling in dark mode and should be used as a reference for fixing this issue.

Steps to Reproduce

1. Navigate to the login or signup page
2. Switch to dark mode
3. Observe the input field labels - notice the incorrect background color behind them

Suggested Fix

Review the CSS implementation used in the employee list page for input fields and apply the same styling approach to the login and signup page input fields.