A login screen can vary in style, features, and effects, depending on the brand identity, target audience, and design goals. However, it should always adhere to the principles of simplicity, security, and user-friendliness. For example, Dropbox has a minimalist and elegant design with a white background, a blue logo, and a simple form. The form has clear labels, placeholders, and icons for the email and password fields, as well as a prominent button for signing in. Netflix's login screen is dark and dynamic with a black background, a red logo, and a video background. The form has large and bold labels and inputs for the email and password fields, and a big button for signing in. Lastly, Spotify's login screen is colorful and modern with a green background, a white logo, and a gradient effect. It has small and sleek labels and inputs for the email and password fields with a flat button for logging in. In all three cases, the links for resetting the password are easy to find while the options for signing up are highlighted in different colors.